Initial source

44 files changed, 3401 insertions, 0 deletions

diff --git a/i386/pc/Makerules b/i386/pc/Makerules
new file mode 100644
index 0000000..eaa1f24
--- /dev/null
+++ b/i386/pc/Makerules
@@ -0,0 +1,30 @@
+#
+# Copyright (c) 1994 The University of Utah and
+# the Center for Software Science (CSS).  All rights reserved.
+#
+# Permission to use, copy, modify and distribute this software and its
+# documentation is hereby granted, provided that both the copyright
+# notice and this permission notice appear in all copies of the
+# software, derivative works or modified versions, and any portions
+# thereof, and that both notices appear in supporting documentation.
+#
+# THE UNIVERSITY OF UTAH AND CSS ALLOW FREE USE OF THIS SOFTWARE IN ITS "AS
+# IS" CONDITION.  THE UNIVERSITY OF UTAH AND CSS DISCLAIM ANY LIABILITY OF
+# ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+#
+# CSS requests users of this software to return to css-dist@cs.utah.edu any
+# improvements that they make and grant CSS redistribution rights.
+#
+#      Author: Bryan Ford, University of Utah CSS
+#
+ifndef _mach4_i386_kernel_pc_makerules_
+_mach4_i386_kernel_pc_makerules = yes
+
+
+CLEAN_FILES += pc_asm.h
+i16_real_int.o: pc_asm.h
+
+include $(MSRCDIR)/kernel/util/Makerules
+
+
+endif
diff --git a/i386/pc/NOTES b/i386/pc/NOTES
new file mode 100644
index 0000000..d165aa4
--- /dev/null
+++ b/i386/pc/NOTES
@@ -0,0 +1,34 @@
+
+
+i16_raw.c:
+	Provides a default implementation
+	of real/pmode switching code.
+	Assumes that, as far as it's concerned,
+	low linear address always map to physical addresses.
+	(The low linear mappings can be changed,
+	but must be changed back before switching back to real mode.)
+
+	Provides:
+		i16_raw_switch_to_pmode()
+		i16_raw_switch_to_real_mode()
+
+		i16_raw_start()
+			Called in real mode.
+			Initializes the pmode switching system,
+			switches to pmode for the first time,
+			and calls the 32-bit function raw_start().
+
+	Depends on:
+
+		paging.h:
+			raw_paging_enable()
+			raw_paging_disable()
+			raw_paging_init()
+
+		a20.h:
+			i16_enable_a20()
+			i16_disable_a20()
+
+		real.h:
+			real_cs
+
diff --git a/i386/pc/debug.h b/i386/pc/debug.h
new file mode 100644
index 0000000..6265082
--- /dev/null
+++ b/i386/pc/debug.h
@@ -0,0 +1,71 @@
+/* 
+ * Copyright (c) 1995-1994 The University of Utah and
+ * the Computer Systems Laboratory at the University of Utah (CSL).
+ * All rights reserved.
+ *
+ * Permission to use, copy, modify and distribute this software is hereby
+ * granted provided that (1) source code retains these copyright, permission,
+ * and disclaimer notices, and (2) redistributions including binaries
+ * reproduce the notices in supporting documentation, and (3) all advertising
+ * materials mentioning features or use of this software display the following
+ * acknowledgement: ``This product includes software developed by the
+ * Computer Systems Laboratory at the University of Utah.''
+ *
+ * THE UNIVERSITY OF UTAH AND CSL ALLOW FREE USE OF THIS SOFTWARE IN ITS "AS
+ * IS" CONDITION.  THE UNIVERSITY OF UTAH AND CSL DISCLAIM ANY LIABILITY OF
+ * ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ *
+ * CSL requests users of this software to return to csl-dist@cs.utah.edu any
+ * improvements that they make and grant CSL redistribution rights.
+ *
+ *      Author: Bryan Ford, University of Utah CSL
+ */
+#ifndef _KUKM_I386_PC_DEBUG_H_
+#define _KUKM_I386_PC_DEBUG_H_
+
+#ifdef ASSEMBLER
+#ifdef DEBUG
+
+
+/* Poke a character directly onto the VGA text display,
+   as a very quick, mostly-reliable status indicator.
+   Assumes ss is a kernel data segment register.  */
+#define POKE_STATUS(char,scratch)		\
+	ss/*XXX gas bug */			;\
+	movl	%ss:_phys_mem_va,scratch	;\
+	addl	$0xb8000+80*2*13+40*2,scratch	;\
+	movb	char,%ss:(scratch)		;\
+	movb	$0xf0,%ss:1(scratch)
+
+
+#else !DEBUG
+
+#define POKE_STATUS(char,scratch)
+
+#endif !DEBUG
+#else !ASSEMBLER
+#ifdef DEBUG
+
+#include <mach/machine/vm_types.h>
+
+
+#define POKE_STATUS(string)						\
+	({	unsigned char *s = (string);				\
+		extern vm_offset_t phys_mem_va;				\
+		short *d = (short*)(phys_mem_va+0xb8000+80*2*13+40*2);	\
+		while (*s) { (*d++) = 0x3000 | (*s++); }		\
+		*d = ' ';						\
+	})
+
+
+#else !DEBUG
+
+#define POKE_STATUS(char)
+
+#endif !DEBUG
+#endif !ASSEMBLER
+
+
+#include_next "debug.h"
+
+#endif _KUKM_I386_PC_DEBUG_H_
diff --git a/i386/pc/exit.c b/i386/pc/exit.c
new file mode 100644
index 0000000..59c9383
--- /dev/null
+++ b/i386/pc/exit.c
@@ -0,0 +1,32 @@
+/* 
+ * Copyright (c) 1995-1994 The University of Utah and
+ * the Computer Systems Laboratory at the University of Utah (CSL).
+ * All rights reserved.
+ *
+ * Permission to use, copy, modify and distribute this software is hereby
+ * granted provided that (1) source code retains these copyright, permission,
+ * and disclaimer notices, and (2) redistributions including binaries
+ * reproduce the notices in supporting documentation, and (3) all advertising
+ * materials mentioning features or use of this software display the following
+ * acknowledgement: ``This product includes software developed by the
+ * Computer Systems Laboratory at the University of Utah.''
+ *
+ * THE UNIVERSITY OF UTAH AND CSL ALLOW FREE USE OF THIS SOFTWARE IN ITS "AS
+ * IS" CONDITION.  THE UNIVERSITY OF UTAH AND CSL DISCLAIM ANY LIABILITY OF
+ * ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ *
+ * CSL requests users of this software to return to csl-dist@cs.utah.edu any
+ * improvements that they make and grant CSL redistribution rights.
+ *
+ *      Author: Bryan Ford, University of Utah CSL
+ */
+
+#include "real.h"
+
+void _exit(int rc)
+{
+	about_to_die(rc);
+
+	(*real_exit)(rc);
+}
+
diff --git a/i386/pc/gdt.h b/i386/pc/gdt.h
new file mode 100644
index 0000000..8dae857
--- /dev/null
+++ b/i386/pc/gdt.h
@@ -0,0 +1,32 @@
+/* 
+ * Copyright (c) 1995-1994 The University of Utah and
+ * the Computer Systems Laboratory at the University of Utah (CSL).
+ * All rights reserved.
+ *
+ * Permission to use, copy, modify and distribute this software is hereby
+ * granted provided that (1) source code retains these copyright, permission,
+ * and disclaimer notices, and (2) redistributions including binaries
+ * reproduce the notices in supporting documentation, and (3) all advertising
+ * materials mentioning features or use of this software display the following
+ * acknowledgement: ``This product includes software developed by the
+ * Computer Systems Laboratory at the University of Utah.''
+ *
+ * THE UNIVERSITY OF UTAH AND CSL ALLOW FREE USE OF THIS SOFTWARE IN ITS "AS
+ * IS" CONDITION.  THE UNIVERSITY OF UTAH AND CSL DISCLAIM ANY LIABILITY OF
+ * ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ *
+ * CSL requests users of this software to return to csl-dist@cs.utah.edu any
+ * improvements that they make and grant CSL redistribution rights.
+ *
+ *      Author: Bryan Ford, University of Utah CSL
+ */
+
+#include_next "gdt.h"
+
+/* If we have a REAL_TSS, use that as our DEFAULT_TSS if necessary.
+   (The DEFAULT_TSS gets loaded by cpu_tables_load() upon switching to pmode.)  */
+#if defined(ENABLE_REAL_TSS) && !defined(DEFAULT_TSS)
+#define DEFAULT_TSS	REAL_TSS
+#define DEFAULT_TSS_IDX	REAL_TSS_IDX
+#endif
+
diff --git a/i386/pc/gdt_sels.h b/i386/pc/gdt_sels.h
new file mode 100644
index 0000000..18e0907
--- /dev/null
+++ b/i386/pc/gdt_sels.h
@@ -0,0 +1,34 @@
+/* 
+ * Copyright (c) 1995-1994 The University of Utah and
+ * the Computer Systems Laboratory at the University of Utah (CSL).
+ * All rights reserved.
+ *
+ * Permission to use, copy, modify and distribute this software is hereby
+ * granted provided that (1) source code retains these copyright, permission,
+ * and disclaimer notices, and (2) redistributions including binaries
+ * reproduce the notices in supporting documentation, and (3) all advertising
+ * materials mentioning features or use of this software display the following
+ * acknowledgement: ``This product includes software developed by the
+ * Computer Systems Laboratory at the University of Utah.''
+ *
+ * THE UNIVERSITY OF UTAH AND CSL ALLOW FREE USE OF THIS SOFTWARE IN ITS "AS
+ * IS" CONDITION.  THE UNIVERSITY OF UTAH AND CSL DISCLAIM ANY LIABILITY OF
+ * ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ *
+ * CSL requests users of this software to return to csl-dist@cs.utah.edu any
+ * improvements that they make and grant CSL redistribution rights.
+ *
+ *      Author: Bryan Ford, University of Utah CSL
+ */
+
+#include_next "gdt_sels.h"
+
+#ifdef ENABLE_REAL_TSS
+
+/* This is a special TSS with a full IO bitmap
+   that allows access to all I/O ports in v86 mode.
+   It's used for making calls to the real-mode BIOS (or DOS).  */
+gdt_sel(REAL_TSS)
+
+#endif
+
diff --git a/i386/pc/i16/i16_a20.c b/i386/pc/i16/i16_a20.c
new file mode 100644
index 0000000..5e91f86
--- /dev/null
+++ b/i386/pc/i16/i16_a20.c
@@ -0,0 +1,144 @@
+/* 
+ * Copyright (c) 1995-1994 The University of Utah and
+ * the Computer Systems Laboratory at the University of Utah (CSL).
+ * All rights reserved.
+ *
+ * Permission to use, copy, modify and distribute this software is hereby
+ * granted provided that (1) source code retains these copyright, permission,
+ * and disclaimer notices, and (2) redistributions including binaries
+ * reproduce the notices in supporting documentation, and (3) all advertising
+ * materials mentioning features or use of this software display the following
+ * acknowledgement: ``This product includes software developed by the
+ * Computer Systems Laboratory at the University of Utah.''
+ *
+ * THE UNIVERSITY OF UTAH AND CSL ALLOW FREE USE OF THIS SOFTWARE IN ITS "AS
+ * IS" CONDITION.  THE UNIVERSITY OF UTAH AND CSL DISCLAIM ANY LIABILITY OF
+ * ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ *
+ * CSL requests users of this software to return to csl-dist@cs.utah.edu any
+ * improvements that they make and grant CSL redistribution rights.
+ *
+ *      Author: Bryan Ford, University of Utah CSL
+ */
+
+
+#include <mach/machine/pio.h>
+#include <mach/machine/code16.h>
+
+#include "i16_a20.h"
+
+
+/* Keyboard stuff for turning on the A20 address line (gak!).  */
+#define K_RDWR 		0x60		/* keyboard data & cmds (read/write) */
+#define K_STATUS 	0x64		/* keyboard status (read-only) */
+#define K_CMD	 	0x64		/* keybd ctlr command (write-only) */
+
+#define K_OBUF_FUL 	0x01		/* output buffer full */
+#define K_IBUF_FUL 	0x02		/* input buffer full */
+
+#define KC_CMD_WIN	0xd0		/* read  output port */
+#define KC_CMD_WOUT	0xd1		/* write output port */
+
+#define KB_ENABLE_A20	0xdf	/* Linux and my BIOS uses this,
+				   and I trust them more than Mach 3.0,
+				   but I'd like to know what the difference is
+				   and if it matters.  */
+			/*0x9f*/	/* enable A20,
+					   enable output buffer full interrupt
+					   enable data line
+					   disable clock line */
+#define KB_DISABLE_A20	0xdd
+
+
+CODE16
+
+
+/*
+   This routine ensures that the keyboard command queue is empty
+   (after emptying the output buffers)
+
+   No timeout is used - if this hangs there is something wrong with
+   the machine, and we probably couldn't proceed anyway.
+   XXX should at least die properly
+*/
+static void i16_empty_8042(void)
+{
+	int status;
+
+retry:
+	i16_nanodelay(1000);
+	status = i16_inb(K_STATUS);
+
+	if (status & K_OBUF_FUL)
+	{
+		i16_nanodelay(1000);
+		i16_inb(K_RDWR);
+		goto retry;
+	}
+
+	if (status & K_IBUF_FUL)
+		goto retry;
+}
+
+int i16_raw_test_a20(void);
+
+/* Enable the A20 address line.  */
+void i16_raw_enable_a20(void)
+{
+	int v;
+
+	/* XXX try int 15h function 24h */
+
+	if (i16_raw_test_a20())
+		return;
+
+	/* PS/2 */
+	v = i16_inb(0x92);
+	i16_nanodelay(1000);
+	i16_outb(0x92,v | 2);
+
+	if (i16_raw_test_a20())
+		return;
+
+	/* AT */
+	i16_empty_8042();
+	i16_outb(K_CMD, KC_CMD_WOUT);
+	i16_empty_8042();
+	i16_outb(K_RDWR, KB_ENABLE_A20);
+	i16_empty_8042();
+
+	/* Wait until the a20 line gets enabled.  */
+	while (!i16_raw_test_a20());
+}
+
+/* Disable the A20 address line.  */
+void i16_raw_disable_a20(void)
+{
+	int v;
+
+	if (!i16_raw_test_a20())
+		return;
+
+	/* PS/2 */
+	v = i16_inb(0x92);
+	i16_nanodelay(1000);
+	i16_outb(0x92, v & ~2);
+
+	if (!i16_raw_test_a20())
+		return;
+
+	/* AT */
+	i16_empty_8042();
+	i16_outb(K_CMD, KC_CMD_WOUT);
+	i16_empty_8042();
+	i16_outb(K_RDWR, KB_DISABLE_A20);
+	i16_empty_8042();
+
+	/* Wait until the a20 line gets disabled.  */
+	while (i16_raw_test_a20());
+}
+
+
+void (*i16_enable_a20)(void) = i16_raw_enable_a20;
+void (*i16_disable_a20)(void) = i16_raw_disable_a20;
+
diff --git a/i386/pc/i16/i16_a20.h b/i386/pc/i16/i16_a20.h
new file mode 100644
index 0000000..afe124b
--- /dev/null
+++ b/i386/pc/i16/i16_a20.h
@@ -0,0 +1,32 @@
+/* 
+ * Copyright (c) 1995-1994 The University of Utah and
+ * the Computer Systems Laboratory at the University of Utah (CSL).
+ * All rights reserved.
+ *
+ * Permission to use, copy, modify and distribute this software is hereby
+ * granted provided that (1) source code retains these copyright, permission,
+ * and disclaimer notices, and (2) redistributions including binaries
+ * reproduce the notices in supporting documentation, and (3) all advertising
+ * materials mentioning features or use of this software display the following
+ * acknowledgement: ``This product includes software developed by the
+ * Computer Systems Laboratory at the University of Utah.''
+ *
+ * THE UNIVERSITY OF UTAH AND CSL ALLOW FREE USE OF THIS SOFTWARE IN ITS "AS
+ * IS" CONDITION.  THE UNIVERSITY OF UTAH AND CSL DISCLAIM ANY LIABILITY OF
+ * ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ *
+ * CSL requests users of this software to return to csl-dist@cs.utah.edu any
+ * improvements that they make and grant CSL redistribution rights.
+ *
+ *      Author: Bryan Ford, University of Utah CSL
+ */
+#ifndef _I386_PC_A20_H_
+#define _I386_PC_A20_H_
+
+/* By default these point to the "raw" routines in pc/a20.c.
+   They can be revectored to other routines,
+   e.g. to use a HIMEM driver's facilities.  */
+extern void (*i16_enable_a20)(void);
+extern void (*i16_disable_a20)(void);
+
+#endif _I386_PC_A20_H_
diff --git a/i386/pc/i16/i16_bios.h b/i386/pc/i16/i16_bios.h
new file mode 100644
index 0000000..29dc2d8
--- /dev/null
+++ b/i386/pc/i16/i16_bios.h
@@ -0,0 +1,98 @@
+/* 
+ * Copyright (c) 1995-1994 The University of Utah and
+ * the Computer Systems Laboratory at the University of Utah (CSL).
+ * All rights reserved.
+ *
+ * Permission to use, copy, modify and distribute this software is hereby
+ * granted provided that (1) source code retains these copyright, permission,
+ * and disclaimer notices, and (2) redistributions including binaries
+ * reproduce the notices in supporting documentation, and (3) all advertising
+ * materials mentioning features or use of this software display the following
+ * acknowledgement: ``This product includes software developed by the
+ * Computer Systems Laboratory at the University of Utah.''
+ *
+ * THE UNIVERSITY OF UTAH AND CSL ALLOW FREE USE OF THIS SOFTWARE IN ITS "AS
+ * IS" CONDITION.  THE UNIVERSITY OF UTAH AND CSL DISCLAIM ANY LIABILITY OF
+ * ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ *
+ * CSL requests users of this software to return to csl-dist@cs.utah.edu any
+ * improvements that they make and grant CSL redistribution rights.
+ *
+ *      Author: Bryan Ford, University of Utah CSL
+ */
+#ifndef _I16_BIOS_H_
+#define _I16_BIOS_H_
+
+#include <mach/inline.h>
+
+
+MACH_INLINE void i16_bios_putchar(int c)
+{
+	asm volatile("int $0x10" : : "a" (0x0e00 | (c & 0xff)), "b" (0x07));
+}
+
+MACH_INLINE int i16_bios_getchar()
+{
+	int c;
+	asm volatile("int $0x16" : "=a" (c) : "a" (0x0000));
+	c &= 0xff;
+	return c;
+}
+
+MACH_INLINE void i16_bios_warm_boot(void)
+{
+	asm volatile("
+		cli
+		movw	$0x40,%ax
+		movw	%ax,%ds
+		movw	$0x1234,0x72
+		ljmp	$0xffff,$0x0000
+	");
+}
+
+MACH_INLINE void i16_bios_cold_boot(void)
+{
+	asm volatile("
+		cli
+		movw	$0x40,%ax
+		movw	%ax,%ds
+		movw	$0x0000,0x72
+		ljmp	$0xffff,$0x0000
+	");
+}
+
+MACH_INLINE unsigned char i16_bios_copy_ext_mem(
+	unsigned src_la, unsigned dest_la, unsigned short word_count)
+{
+	char buf[48];
+	unsigned short i, rc;
+
+	/* Initialize the descriptor structure.  */
+	for (i = 0; i < sizeof(buf); i++)
+		buf[i] = 0;
+	*((unsigned short*)(buf+0x10)) = 0xffff; /* source limit */
+	*((unsigned long*)(buf+0x12)) = src_la; /* source linear address */
+	*((unsigned char*)(buf+0x15)) = 0x93; /* source access rights */
+	*((unsigned short*)(buf+0x18)) = 0xffff; /* dest limit */
+	*((unsigned long*)(buf+0x1a)) = dest_la; /* dest linear address */
+	*((unsigned char*)(buf+0x1d)) = 0x93; /* dest access rights */
+
+#if 0
+	i16_puts("buf:");
+	for (i = 0; i < sizeof(buf); i++)
+		i16_writehexb(buf[i]);
+	i16_puts("");
+#endif
+
+	/* Make the BIOS call to perform the copy.  */
+	asm volatile("
+		int	$0x15
+	" : "=a" (rc)
+	  : "a" ((unsigned short)0x8700),
+	    "c" (word_count),
+	    "S" ((unsigned short)(unsigned)buf));
+
+	return rc >> 8;
+}
+
+#endif _I16_BIOS_H_
diff --git a/i386/pc/i16/i16_exit.c b/i386/pc/i16/i16_exit.c
new file mode 100644
index 0000000..674033a
--- /dev/null
+++ b/i386/pc/i16/i16_exit.c
@@ -0,0 +1,37 @@
+/* 
+ * Copyright (c) 1995-1994 The University of Utah and
+ * the Computer Systems Laboratory at the University of Utah (CSL).
+ * All rights reserved.
+ *
+ * Permission to use, copy, modify and distribute this software is hereby
+ * granted provided that (1) source code retains these copyright, permission,
+ * and disclaimer notices, and (2) redistributions including binaries
+ * reproduce the notices in supporting documentation, and (3) all advertising
+ * materials mentioning features or use of this software display the following
+ * acknowledgement: ``This product includes software developed by the
+ * Computer Systems Laboratory at the University of Utah.''
+ *
+ * THE UNIVERSITY OF UTAH AND CSL ALLOW FREE USE OF THIS SOFTWARE IN ITS "AS
+ * IS" CONDITION.  THE UNIVERSITY OF UTAH AND CSL DISCLAIM ANY LIABILITY OF
+ * ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ *
+ * CSL requests users of this software to return to csl-dist@cs.utah.edu any
+ * improvements that they make and grant CSL redistribution rights.
+ *
+ *      Author: Bryan Ford, University of Utah CSL
+ */
+
+#include <mach/machine/code16.h>
+
+#include "i16_bios.h"
+
+
+CODE16
+
+void i16_exit(int rc)
+{
+	i16_puts("Press any key to reboot.");
+	i16_bios_getchar();
+	i16_bios_warm_boot();
+}
+
diff --git a/i386/pc/i16/i16_ext_mem.c b/i386/pc/i16/i16_ext_mem.c
new file mode 100644
index 0000000..08cbecf
--- /dev/null
+++ b/i386/pc/i16/i16_ext_mem.c
@@ -0,0 +1,151 @@
+/* 
+ * Copyright (c) 1995-1994 The University of Utah and
+ * the Computer Systems Laboratory at the University of Utah (CSL).
+ * All rights reserved.
+ *
+ * Permission to use, copy, modify and distribute this software is hereby
+ * granted provided that (1) source code retains these copyright, permission,
+ * and disclaimer notices, and (2) redistributions including binaries
+ * reproduce the notices in supporting documentation, and (3) all advertising
+ * materials mentioning features or use of this software display the following
+ * acknowledgement: ``This product includes software developed by the
+ * Computer Systems Laboratory at the University of Utah.''
+ *
+ * THE UNIVERSITY OF UTAH AND CSL ALLOW FREE USE OF THIS SOFTWARE IN ITS "AS
+ * IS" CONDITION.  THE UNIVERSITY OF UTAH AND CSL DISCLAIM ANY LIABILITY OF
+ * ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ *
+ * CSL requests users of this software to return to csl-dist@cs.utah.edu any
+ * improvements that they make and grant CSL redistribution rights.
+ *
+ *      Author: Bryan Ford, University of Utah CSL
+ */
+
+#include <mach/machine/code16.h>
+#include <mach/machine/vm_types.h>
+#include <mach/machine/far_ptr.h>
+#include <mach/machine/proc_reg.h>
+
+#include "i16_bios.h"
+#include "phys_mem.h"
+#include "vm_param.h"
+#include "debug.h"
+
+
+static vm_offset_t ext_mem_phys_free_mem;
+static vm_size_t ext_mem_phys_free_size;
+
+
+CODE32
+
+int ext_mem_collect(void)
+{
+	if (ext_mem_phys_free_mem)
+	{
+		phys_mem_add(ext_mem_phys_free_mem, ext_mem_phys_free_size);
+		ext_mem_phys_free_mem = 0;
+	}
+}
+
+CODE16
+
+void i16_ext_mem_check()
+{
+	vm_offset_t ext_mem_top, ext_mem_bot;
+	unsigned short ext_mem_k;
+
+	/* Find the top of available extended memory.  */
+	asm volatile("
+		int	$0x15
+		jnc	1f
+		xorw	%%ax,%%ax
+	1:
+	" : "=a" (ext_mem_k)
+	  : "a" (0x8800));
+	ext_mem_top = 0x100000 + (vm_offset_t)ext_mem_k * 1024;
+
+	/* XXX check for >16MB memory using function 0xc7 */
+
+	ext_mem_bot = 0x100000;
+
+	/* Check for extended memory allocated bottom-up: method 1.
+	   This uses the technique (and, loosely, the code)
+	   described in the VCPI spec, version 1.0.  */
+	if (ext_mem_top > ext_mem_bot)
+	{
+		asm volatile("
+			pushw	%%es
+
+			xorw	%%ax,%%ax
+			movw	%%ax,%%es
+			movw	%%es:0x19*4+2,%%ax
+			movw	%%ax,%%es
+
+			movw	$0x12,%%di
+			movw	$7,%%cx
+			rep
+			cmpsb
+			jne	1f
+
+			xorl	%%edx,%%edx
+			movb	%%es:0x2e,%%dl
+			shll	$16,%%edx
+			movw	%%es:0x2c,%%dx
+
+		1:
+			popw	%%es
+		" : "=d" (ext_mem_bot)
+		  : "d" (ext_mem_bot),
+		    "S" ((unsigned short)(vm_offset_t)"VDISK V")
+		  : "eax", "ecx", "esi", "edi");
+	}
+	i16_assert(ext_mem_bot >= 0x100000);
+
+	/* Check for extended memory allocated bottom-up: method 2.
+	   This uses the technique (and, loosely, the code)
+	   described in the VCPI spec, version 1.0.  */
+	if (ext_mem_top > ext_mem_bot)
+	{
+		struct {
+			char pad1[3];
+			char V;
+			long DISK;
+			char pad2[30-8];
+			unsigned short addr;
+		} buf;
+		unsigned char rc;
+
+		i16_assert(sizeof(buf) == 0x20);
+		rc = i16_bios_copy_ext_mem(0x100000, kvtolin((vm_offset_t)&buf), sizeof(buf)/2);
+		if ((rc == 0) && (buf.V == 'V') && (buf.DISK == 'DISK'))
+		{
+			vm_offset_t new_bot = (vm_offset_t)buf.addr << 10;
+			i16_assert(new_bot > 0x100000);
+			if (new_bot > ext_mem_bot)
+				ext_mem_bot = new_bot;
+		}
+	}
+	i16_assert(ext_mem_bot >= 0x100000);
+
+	if (ext_mem_top > ext_mem_bot)
+	{
+		ext_mem_phys_free_mem = ext_mem_bot;
+		ext_mem_phys_free_size = ext_mem_top - ext_mem_bot;
+
+		/* We need to update phys_mem_max here
+		   instead of just letting phys_mem_add() do it
+		   when the memory is collected with phys_mem_collect(),
+		   because VCPI initialization needs to know the top of physical memory
+		   before phys_mem_collect() is called.
+		   See i16_vcpi.c for the gross details.  */
+		if (ext_mem_top > phys_mem_max)
+			phys_mem_max = ext_mem_top;
+	}
+}
+
+void i16_ext_mem_shutdown()
+{
+	/* We didn't actually allocate the memory,
+	   so no need to deallocate it... */
+}
+
diff --git a/i386/pc/i16/i16_init.c b/i386/pc/i16/i16_init.c
new file mode 100644
index 0000000..23a51df
--- /dev/null
+++ b/i386/pc/i16/i16_init.c
@@ -0,0 +1,67 @@
+/* 
+ * Copyright (c) 1995-1994 The University of Utah and
+ * the Computer Systems Laboratory at the University of Utah (CSL).
+ * All rights reserved.
+ *
+ * Permission to use, copy, modify and distribute this software is hereby
+ * granted provided that (1) source code retains these copyright, permission,
+ * and disclaimer notices, and (2) redistributions including binaries
+ * reproduce the notices in supporting documentation, and (3) all advertising
+ * materials mentioning features or use of this software display the following
+ * acknowledgement: ``This product includes software developed by the
+ * Computer Systems Laboratory at the University of Utah.''
+ *
+ * THE UNIVERSITY OF UTAH AND CSL ALLOW FREE USE OF THIS SOFTWARE IN ITS "AS
+ * IS" CONDITION.  THE UNIVERSITY OF UTAH AND CSL DISCLAIM ANY LIABILITY OF
+ * ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ *
+ * CSL requests users of this software to return to csl-dist@cs.utah.edu any
+ * improvements that they make and grant CSL redistribution rights.
+ *
+ *      Author: Bryan Ford, University of Utah CSL
+ */
+
+#include <mach/machine/code16.h>
+#include <mach/machine/proc_reg.h>
+
+#include "vm_param.h"
+
+
+/* Code segment we originally had when we started in real mode.  */
+unsigned short real_cs;
+
+/* Virtual address of physical memory.  */
+vm_offset_t phys_mem_va;
+
+/* Physical address of start of boot image.  */
+vm_offset_t boot_image_pa;
+
+/* Upper limit of known physical memory.  */
+vm_offset_t phys_mem_max;
+
+
+CODE16
+
+#include "i16_bios.h"
+
+/* Called by i16_crt0 (or the equivalent)
+   to set up our basic 16-bit runtime environment
+   before calling i16_main().  */
+void i16_init(void)
+{
+	/* Find our code/data/everything segment.  */
+	real_cs = get_cs();
+
+	/* Find out where in physical memory we got loaded.  */
+	boot_image_pa = real_cs << 4;
+
+	/* Find out where the bottom of physical memory is.
+	   (We won't be able to directly use it for 32-bit accesses
+	   until we actually get into 32-bit mode.)  */
+	phys_mem_va = -boot_image_pa;
+
+	/* The base of linear memory is at the same place,
+	   at least until we turn paging on.  */
+	linear_base_va = phys_mem_va;
+}
+
diff --git a/i386/pc/i16/i16_main.c b/i386/pc/i16/i16_main.c
new file mode 100644
index 0000000..328cceb
--- /dev/null
+++ b/i386/pc/i16/i16_main.c
@@ -0,0 +1,38 @@
+/* 
+ * Copyright (c) 1995-1994 The University of Utah and
+ * the Computer Systems Laboratory at the University of Utah (CSL).
+ * All rights reserved.
+ *
+ * Permission to use, copy, modify and distribute this software is hereby
+ * granted provided that (1) source code retains these copyright, permission,
+ * and disclaimer notices, and (2) redistributions including binaries
+ * reproduce the notices in supporting documentation, and (3) all advertising
+ * materials mentioning features or use of this software display the following
+ * acknowledgement: ``This product includes software developed by the
+ * Computer Systems Laboratory at the University of Utah.''
+ *
+ * THE UNIVERSITY OF UTAH AND CSL ALLOW FREE USE OF THIS SOFTWARE IN ITS "AS
+ * IS" CONDITION.  THE UNIVERSITY OF UTAH AND CSL DISCLAIM ANY LIABILITY OF
+ * ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ *
+ * CSL requests users of this software to return to csl-dist@cs.utah.edu any
+ * improvements that they make and grant CSL redistribution rights.
+ *
+ *      Author: Bryan Ford, University of Utah CSL
+ */
+
+#include <mach/machine/code16.h>
+
+
+CODE16
+
+void i16_main(void)
+{
+	i16_init();
+
+	/* Grab all the memory we can find.  */
+	i16_ext_mem_check();
+
+	i16_raw_start();
+}
+
diff --git a/i386/pc/i16/i16_pic.c b/i386/pc/i16/i16_pic.c
new file mode 100644
index 0000000..3ff2697
--- /dev/null
+++ b/i386/pc/i16/i16_pic.c
@@ -0,0 +1,66 @@
+/* 
+ * Copyright (c) 1995 The University of Utah and
+ * the Computer Systems Laboratory at the University of Utah (CSL).
+ * All rights reserved.
+ *
+ * Permission to use, copy, modify and distribute this software is hereby
+ * granted provided that (1) source code retains these copyright, permission,
+ * and disclaimer notices, and (2) redistributions including binaries
+ * reproduce the notices in supporting documentation, and (3) all advertising
+ * materials mentioning features or use of this software display the following
+ * acknowledgement: ``This product includes software developed by the
+ * Computer Systems Laboratory at the University of Utah.''
+ *
+ * THE UNIVERSITY OF UTAH AND CSL ALLOW FREE USE OF THIS SOFTWARE IN ITS "AS
+ * IS" CONDITION.  THE UNIVERSITY OF UTAH AND CSL DISCLAIM ANY LIABILITY OF
+ * ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ *
+ * CSL requests users of this software to return to csl-dist@cs.utah.edu any
+ * improvements that they make and grant CSL redistribution rights.
+ *
+ *      Author: Bryan Ford, University of Utah CSL
+ */
+
+#include <mach/machine/pio.h>
+
+#include "pic.h"
+#include "i16.h"
+
+CODE16
+
+/* Program the PICs to use a different set of interrupt vectors.
+   Assumes processor I flag is off.  */
+void i16_pic_set_master(int base)
+{
+	unsigned char old_mask;
+
+	/* Save the original interrupt mask.  */
+	old_mask = inb(MASTER_OCW);	PIC_DELAY();
+
+	/* Initialize the master PIC.  */
+	outb(MASTER_ICW, PICM_ICW1);	PIC_DELAY();
+	outb(MASTER_OCW, base);		PIC_DELAY();
+	outb(MASTER_OCW, PICM_ICW3);	PIC_DELAY();
+	outb(MASTER_OCW, PICM_ICW4);	PIC_DELAY();
+
+	/* Restore the original interrupt mask.  */
+	outb(MASTER_OCW, old_mask);	PIC_DELAY();
+}
+
+void i16_pic_set_slave(int base)
+{
+	unsigned char old_mask;
+
+	/* Save the original interrupt mask.  */
+	old_mask = inb(SLAVES_OCW);	PIC_DELAY();
+
+	/* Initialize the slave PIC.  */
+	outb(SLAVES_ICW, PICS_ICW1);	PIC_DELAY();
+	outb(SLAVES_OCW, base);		PIC_DELAY();
+	outb(SLAVES_OCW, PICS_ICW3);	PIC_DELAY();
+	outb(SLAVES_OCW, PICS_ICW4);	PIC_DELAY();
+
+	/* Restore the original interrupt mask.  */
+	outb(SLAVES_OCW, old_mask);	PIC_DELAY();
+}
+
diff --git a/i386/pc/i16/i16_putchar.c b/i386/pc/i16/i16_putchar.c
new file mode 100644
index 0000000..365f4f8
--- /dev/null
+++ b/i386/pc/i16/i16_putchar.c
@@ -0,0 +1,36 @@
+/* 
+ * Copyright (c) 1995-1994 The University of Utah and
+ * the Computer Systems Laboratory at the University of Utah (CSL).
+ * All rights reserved.
+ *
+ * Permission to use, copy, modify and distribute this software is hereby
+ * granted provided that (1) source code retains these copyright, permission,
+ * and disclaimer notices, and (2) redistributions including binaries
+ * reproduce the notices in supporting documentation, and (3) all advertising
+ * materials mentioning features or use of this software display the following
+ * acknowledgement: ``This product includes software developed by the
+ * Computer Systems Laboratory at the University of Utah.''
+ *
+ * THE UNIVERSITY OF UTAH AND CSL ALLOW FREE USE OF THIS SOFTWARE IN ITS "AS
+ * IS" CONDITION.  THE UNIVERSITY OF UTAH AND CSL DISCLAIM ANY LIABILITY OF
+ * ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ *
+ * CSL requests users of this software to return to csl-dist@cs.utah.edu any
+ * improvements that they make and grant CSL redistribution rights.
+ *
+ *      Author: Bryan Ford, University of Utah CSL
+ */
+
+#include <mach/machine/code16.h>
+
+#include "i16_bios.h"
+
+CODE16
+
+void i16_putchar(int ch)
+{
+	if (ch == '\n')
+		i16_bios_putchar('\r');
+	i16_bios_putchar(ch);
+}
+
diff --git a/i386/pc/i16/i16_raw.c b/i386/pc/i16/i16_raw.c
new file mode 100644
index 0000000..1f705d3
--- /dev/null
+++ b/i386/pc/i16/i16_raw.c
@@ -0,0 +1,265 @@
+/* 
+ * Copyright (c) 1995-1994 The University of Utah and
+ * the Computer Systems Laboratory at the University of Utah (CSL).
+ * All rights reserved.
+ *
+ * Permission to use, copy, modify and distribute this software is hereby
+ * granted provided that (1) source code retains these copyright, permission,
+ * and disclaimer notices, and (2) redistributions including binaries
+ * reproduce the notices in supporting documentation, and (3) all advertising
+ * materials mentioning features or use of this software display the following
+ * acknowledgement: ``This product includes software developed by the
+ * Computer Systems Laboratory at the University of Utah.''
+ *
+ * THE UNIVERSITY OF UTAH AND CSL ALLOW FREE USE OF THIS SOFTWARE IN ITS "AS
+ * IS" CONDITION.  THE UNIVERSITY OF UTAH AND CSL DISCLAIM ANY LIABILITY OF
+ * ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ *
+ * CSL requests users of this software to return to csl-dist@cs.utah.edu any
+ * improvements that they make and grant CSL redistribution rights.
+ *
+ *      Author: Bryan Ford, University of Utah CSL
+ */
+/*
+	This file rovides a default implementation
+	of real/pmode switching code.
+	Assumes that, as far as it's concerned,
+	low linear address always map to physical addresses.
+	(The low linear mappings can be changed,
+	but must be changed back before switching back to real mode.)
+
+	Provides:
+		i16_raw_switch_to_pmode()
+		i16_raw_switch_to_real_mode()
+
+		i16_raw_start()
+			Called in real mode.
+			Initializes the pmode switching system,
+			switches to pmode for the first time,
+			and calls the 32-bit function raw_start().
+
+	Depends on:
+
+		paging.h:
+			raw_paging_enable()
+			raw_paging_disable()
+			raw_paging_init()
+
+		a20.h:
+			i16_enable_a20()
+			i16_disable_a20()
+
+		real.h:
+			real_cs
+*/
+
+#include <mach/boolean.h>
+#include <mach/machine/code16.h>
+#include <mach/machine/vm_param.h>
+#include <mach/machine/proc_reg.h>
+#include <mach/machine/pio.h>
+#include <mach/machine/seg.h>
+#include <mach/machine/eflags.h>
+#include <mach/machine/pmode.h>
+
+#include "config.h"
+#include "cpu.h"
+#include "i16.h"
+#include "vm_param.h"
+#include "pic.h"
+#include "debug.h"
+#include "i16_a20.h"
+#include "i16_switch.h"
+
+int irq_master_base, irq_slave_base;
+
+/* Set to true when everything is initialized properly.  */
+static boolean_t inited;
+
+/* Saved value of eflags register for real mode.  */
+static unsigned real_eflags;
+
+
+
+#ifdef ENABLE_PAGING
+#define RAW_PAGING_ENABLE() raw_paging_enable()
+#define RAW_PAGING_DISABLE() raw_paging_disable()
+#define RAW_PAGING_INIT() raw_paging_init()
+#else
+#define RAW_PAGING_ENABLE() ((void)0)
+#define RAW_PAGING_DISABLE() ((void)0)
+#define RAW_PAGING_INIT() ((void)0)
+#endif
+
+
+CODE16
+
+void i16_raw_switch_to_pmode()
+{
+	/* No interrupts from now on please.  */
+	i16_cli();
+
+	/* Save the eflags register for switching back later.  */
+	real_eflags = get_eflags();
+
+	/* Enable the A20 address line.  */
+	i16_enable_a20();
+
+	/* Load the GDT.
+	   Note that we have to do this each time we enter pmode,
+	   not just the first,
+	   because other real-mode programs may have switched to pmode
+	   and back again in the meantime, trashing the GDT pointer.  */
+	{
+		struct pseudo_descriptor pdesc;
+
+		pdesc.limit = sizeof(cpu[0].tables.gdt)-1;
+		pdesc.linear_base = boot_image_pa
+				    + (vm_offset_t)&cpu[0].tables.gdt;
+		i16_set_gdt(&pdesc);
+	}
+
+	/* Switch into protected mode.  */
+	i16_enter_pmode(KERNEL_16_CS);
+
+	/* Reload all the segment registers from the new GDT.  */
+	set_ds(KERNEL_DS);
+	set_es(KERNEL_DS);
+	set_fs(0);
+	set_gs(0);
+	set_ss(KERNEL_DS);
+
+	i16_do_32bit(
+
+		if (inited)
+		{
+			/* Turn paging on if necessary.  */
+			RAW_PAGING_ENABLE();
+
+			/* Load the CPU tables into the processor.  */
+			cpu_tables_load(&cpu[0]);
+
+			/* Program the PIC so the interrupt vectors won't
+			   conflict with the processor exception vectors.  */
+			pic_init(PICM_VECTBASE, PICS_VECTBASE);
+		}
+
+		/* Make sure our flags register is appropriate.  */
+		set_eflags((get_eflags()
+			   & ~(EFL_IF | EFL_DF | EFL_NT))
+			   | EFL_IOPL_USER);
+	);
+}
+
+void i16_raw_switch_to_real_mode()
+{
+	/* Make sure interrupts are disabled.  */
+	cli();
+
+	/* Avoid sending DOS bogus coprocessor exceptions.
+	   XXX should we save/restore all of CR0?  */
+	i16_clts();
+
+	i16_do_32bit(
+		/* Turn paging off if necessary.  */
+		RAW_PAGING_DISABLE();
+
+		/* Reprogram the PIC back to the settings DOS expects.  */
+		pic_init(0x08, 0x70);
+	);
+
+	/* Make sure all the segment registers are 16-bit.
+	   The code segment definitely is already,
+	   because we're running 16-bit code.  */
+	set_ds(KERNEL_16_DS);
+	set_es(KERNEL_16_DS);
+	set_fs(KERNEL_16_DS);
+	set_gs(KERNEL_16_DS);
+	set_ss(KERNEL_16_DS);
+
+	/* Switch back to real mode.  */
+	i16_leave_pmode(real_cs);
+
+	/* Load the real-mode segment registers.  */
+	set_ds(real_cs);
+	set_es(real_cs);
+	set_fs(real_cs);
+	set_gs(real_cs);
+	set_ss(real_cs);
+
+	/* Load the real-mode IDT.  */
+	{
+		struct pseudo_descriptor pdesc;
+
+		pdesc.limit = 0xffff;
+		pdesc.linear_base = 0;
+		i16_set_idt(&pdesc);
+	}
+
+	/* Disable the A20 address line.  */
+	i16_disable_a20();
+
+	/* Restore the eflags register to its original real-mode state.
+	   Note that this will leave interrupts disabled
+	   since it was saved after the cli() above.  */
+	set_eflags(real_eflags);
+}
+
+void i16_raw_start()
+{
+	/* Make sure we're not already in protected mode.  */
+	if (i16_get_msw() & CR0_PE)
+		i16_die("The processor is in an unknown "
+			"protected mode environment.");
+
+	do_debug(i16_puts("Real mode detected"));
+
+	/* Minimally initialize the GDT.  */
+	i16_gdt_init_temp();
+
+	/* Switch to protected mode for the first time.
+	   This won't load all the processor tables and everything yet,
+	   since they're not fully initialized.  */
+	i16_raw_switch_to_pmode();
+
+	/* We can now hop in and out of 32-bit mode at will.  */
+	i16_do_32bit(
+
+		/* Now that we can access all physical memory,
+		   collect the memory regions we discovered while in 16-bit mode
+		   and add them to our free memory list.
+		   We can't do this before now because the free list nodes
+		   are stored in the free memory itself,
+		   which is probably out of reach of our 16-bit segments.  */
+		phys_mem_collect();
+
+		/* Initialize paging if necessary.
+		   Do it before initializing the other processor tables
+		   because they might have to be located
+		   somewhere in high linear memory.  */
+		RAW_PAGING_INIT();
+
+		/* Initialize the processor tables.  */
+		cpu_init(&cpu[0]);
+
+		/* Initialize the hardware interrupt vectors in the IDT.  */
+		irq_master_base = PICM_VECTBASE;
+		irq_slave_base = PICS_VECTBASE;
+		idt_irq_init();
+
+		inited = TRUE;
+
+		/* Switch to real mode and back again once more,
+		   to make sure everything's loaded properly.  */
+		do_16bit(
+			i16_raw_switch_to_real_mode();
+			i16_raw_switch_to_pmode();
+		);
+
+		raw_start();
+	);
+}
+
+void (*i16_switch_to_real_mode)() = i16_raw_switch_to_real_mode;
+void (*i16_switch_to_pmode)() = i16_raw_switch_to_pmode;
+
diff --git a/i386/pc/i16/i16_raw_test_a20.S b/i386/pc/i16/i16_raw_test_a20.S
new file mode 100644
index 0000000..a934e12
--- /dev/null
+++ b/i386/pc/i16/i16_raw_test_a20.S
@@ -0,0 +1,35 @@
+
+#include <mach/machine/asm.h>
+
+	.text
+	.code16
+
+/*
+ * Test the A20 address line; return true if it is enabled.
+ */
+ENTRY(i16_raw_test_a20)
+	xorw	%ax,%ax
+	movw	%ax,%fs
+	notw	%ax
+	movw	%ax,%gs
+
+	/* See if the values in already in the corresponding locations
+	   are the same.  */
+	movw	%fs:0,%ax
+	cmpw	%gs:16,%ax
+	jnz	1f
+
+	/* Yes; try changing one and see if they're still the same.  */
+	movw	%ax,%dx
+	notw	%ax
+	movw	%ax,%fs:0
+	cmpw	%gs:16,%ax
+	movw	%dx,%fs:0
+	jnz	1f
+
+	xorl	%eax,%eax
+	ret
+1:
+	movl	$1,%eax
+	ret
+
diff --git a/i386/pc/i16/i16_real_int.S b/i386/pc/i16/i16_real_int.S
new file mode 100644
index 0000000..f05077e
--- /dev/null
+++ b/i386/pc/i16/i16_real_int.S
@@ -0,0 +1,84 @@
+/* 
+ * Copyright (c) 1995-1994 The University of Utah and
+ * the Computer Systems Laboratory at the University of Utah (CSL).
+ * All rights reserved.
+ *
+ * Permission to use, copy, modify and distribute this software is hereby
+ * granted provided that (1) source code retains these copyright, permission,
+ * and disclaimer notices, and (2) redistributions including binaries
+ * reproduce the notices in supporting documentation, and (3) all advertising
+ * materials mentioning features or use of this software display the following
+ * acknowledgement: ``This product includes software developed by the
+ * Computer Systems Laboratory at the University of Utah.''
+ *
+ * THE UNIVERSITY OF UTAH AND CSL ALLOW FREE USE OF THIS SOFTWARE IN ITS "AS
+ * IS" CONDITION.  THE UNIVERSITY OF UTAH AND CSL DISCLAIM ANY LIABILITY OF
+ * ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ *
+ * CSL requests users of this software to return to csl-dist@cs.utah.edu any
+ * improvements that they make and grant CSL redistribution rights.
+ *
+ *      Author: Bryan Ford, University of Utah CSL
+ */
+
+#include <mach/machine/asm.h>
+
+#include "pc_asm.h"
+
+	.text
+	.code16
+
+ENTRY(i16_real_int)
+	pushf
+	pushl	%ebx
+	pushl	%esi
+	pushl	%edi
+	pushl	%ebp
+
+	cli
+
+	movl	6*4(%esp),%eax
+	movb	%al,1f+1
+
+	movl	7*4(%esp),%ebp
+	movl	RCD_EAX(%ebp),%eax
+	movl	RCD_EBX(%ebp),%ebx
+	movl	RCD_ECX(%ebp),%ecx
+	movl	RCD_EDX(%ebp),%edx
+	movl	RCD_ESI(%ebp),%esi
+	movl	RCD_EDI(%ebp),%edi
+	movw	RCD_DS(%ebp),%ds
+	movw	RCD_ES(%ebp),%es
+	/* XXX flags */
+	movl	RCD_EBP(%ebp),%ebp
+
+1:	int	$0
+
+	pushl	%ebp
+	movl	8*4(%esp),%ebp
+	popl	RCD_EBP(%ebp)
+
+	movl	%eax,RCD_EAX(%ebp)
+	movl	%ebx,RCD_EBX(%ebp)
+	movl	%ecx,RCD_ECX(%ebp)
+	movl	%edx,RCD_EDX(%ebp)
+	movl	%esi,RCD_ESI(%ebp)
+	movl	%edi,RCD_EDI(%ebp)
+	movw	%ds,RCD_DS(%ebp)
+	movw	%es,RCD_ES(%ebp)
+
+	pushf
+	popl	%eax
+	movw	%ax,RCD_FLAGS(%ebp)
+
+	movw	%ss,%ax
+	movw	%ax,%ds
+	movw	%ax,%es
+
+	popl	%ebp
+	popl	%edi
+	popl	%esi
+	popl	%ebx
+	popf
+	ret
+
diff --git a/i386/pc/i16/i16_switch.h b/i386/pc/i16/i16_switch.h
new file mode 100644
index 0000000..b7ecf18
--- /dev/null
+++ b/i386/pc/i16/i16_switch.h
@@ -0,0 +1,30 @@
+/* 
+ * Copyright (c) 1995-1994 The University of Utah and
+ * the Computer Systems Laboratory at the University of Utah (CSL).
+ * All rights reserved.
+ *
+ * Permission to use, copy, modify and distribute this software is hereby
+ * granted provided that (1) source code retains these copyright, permission,
+ * and disclaimer notices, and (2) redistributions including binaries
+ * reproduce the notices in supporting documentation, and (3) all advertising
+ * materials mentioning features or use of this software display the following
+ * acknowledgement: ``This product includes software developed by the
+ * Computer Systems Laboratory at the University of Utah.''
+ *
+ * THE UNIVERSITY OF UTAH AND CSL ALLOW FREE USE OF THIS SOFTWARE IN ITS "AS
+ * IS" CONDITION.  THE UNIVERSITY OF UTAH AND CSL DISCLAIM ANY LIABILITY OF
+ * ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ *
+ * CSL requests users of this software to return to csl-dist@cs.utah.edu any
+ * improvements that they make and grant CSL redistribution rights.
+ *
+ *      Author: Bryan Ford, University of Utah CSL
+ */
+#ifndef _I386_PC_SWITCH_H_
+#define _I386_PC_SWITCH_H_
+
+/* Vectors to routines to switch between real and protected mode.  */
+extern void (*i16_switch_to_real_mode)();
+extern void (*i16_switch_to_pmode)();
+
+#endif _I386_PC_SWITCH_H_
diff --git a/i386/pc/i16/phys_mem_collect.c b/i386/pc/i16/phys_mem_collect.c
new file mode 100644
index 0000000..bcb0c09
--- /dev/null
+++ b/i386/pc/i16/phys_mem_collect.c
@@ -0,0 +1,34 @@
+/* 
+ * Copyright (c) 1995 The University of Utah and
+ * the Computer Systems Laboratory at the University of Utah (CSL).
+ * All rights reserved.
+ *
+ * Permission to use, copy, modify and distribute this software is hereby
+ * granted provided that (1) source code retains these copyright, permission,
+ * and disclaimer notices, and (2) redistributions including binaries
+ * reproduce the notices in supporting documentation, and (3) all advertising
+ * materials mentioning features or use of this software display the following
+ * acknowledgement: ``This product includes software developed by the
+ * Computer Systems Laboratory at the University of Utah.''
+ *
+ * THE UNIVERSITY OF UTAH AND CSL ALLOW FREE USE OF THIS SOFTWARE IN ITS "AS
+ * IS" CONDITION.  THE UNIVERSITY OF UTAH AND CSL DISCLAIM ANY LIABILITY OF
+ * ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ *
+ * CSL requests users of this software to return to csl-dist@cs.utah.edu any
+ * improvements that they make and grant CSL redistribution rights.
+ *
+ *      Author: Bryan Ford, University of Utah CSL
+ */
+
+#include <mach/machine/vm_param.h>
+
+#include "phys_mem.h"
+
+void phys_mem_collect(void)
+{
+#define pms(name) name##_collect();
+#include "phys_mem_sources.h"
+#undef pms
+}
+
diff --git a/i386/pc/i16/phys_mem_sources.h b/i386/pc/i16/phys_mem_sources.h
new file mode 100644
index 0000000..788910d
--- /dev/null
+++ b/i386/pc/i16/phys_mem_sources.h
@@ -0,0 +1,25 @@
+/* 
+ * Copyright (c) 1995-1994 The University of Utah and
+ * the Computer Systems Laboratory at the University of Utah (CSL).
+ * All rights reserved.
+ *
+ * Permission to use, copy, modify and distribute this software is hereby
+ * granted provided that (1) source code retains these copyright, permission,
+ * and disclaimer notices, and (2) redistributions including binaries
+ * reproduce the notices in supporting documentation, and (3) all advertising
+ * materials mentioning features or use of this software display the following
+ * acknowledgement: ``This product includes software developed by the
+ * Computer Systems Laboratory at the University of Utah.''
+ *
+ * THE UNIVERSITY OF UTAH AND CSL ALLOW FREE USE OF THIS SOFTWARE IN ITS "AS
+ * IS" CONDITION.  THE UNIVERSITY OF UTAH AND CSL DISCLAIM ANY LIABILITY OF
+ * ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ *
+ * CSL requests users of this software to return to csl-dist@cs.utah.edu any
+ * improvements that they make and grant CSL redistribution rights.
+ *
+ *      Author: Bryan Ford, University of Utah CSL
+ */
+
+pms(ext_mem)
+
diff --git a/i386/pc/i16/raw_exit.c b/i386/pc/i16/raw_exit.c
new file mode 100644
index 0000000..5ccb69a
--- /dev/null
+++ b/i386/pc/i16/raw_exit.c
@@ -0,0 +1,41 @@
+/* 
+ * Copyright (c) 1995-1994 The University of Utah and
+ * the Computer Systems Laboratory at the University of Utah (CSL).
+ * All rights reserved.
+ *
+ * Permission to use, copy, modify and distribute this software is hereby
+ * granted provided that (1) source code retains these copyright, permission,
+ * and disclaimer notices, and (2) redistributions including binaries
+ * reproduce the notices in supporting documentation, and (3) all advertising
+ * materials mentioning features or use of this software display the following
+ * acknowledgement: ``This product includes software developed by the
+ * Computer Systems Laboratory at the University of Utah.''
+ *
+ * THE UNIVERSITY OF UTAH AND CSL ALLOW FREE USE OF THIS SOFTWARE IN ITS "AS
+ * IS" CONDITION.  THE UNIVERSITY OF UTAH AND CSL DISCLAIM ANY LIABILITY OF
+ * ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ *
+ * CSL requests users of this software to return to csl-dist@cs.utah.edu any
+ * improvements that they make and grant CSL redistribution rights.
+ *
+ *      Author: Bryan Ford, University of Utah CSL
+ */
+
+#include <mach/machine/seg.h>
+#include <mach/machine/proc_reg.h>
+
+#include "i16.h"
+#include "debug.h"
+
+
+void raw_exit(int rc)
+{
+	do_16bit(
+		i16_raw_switch_to_real_mode();
+		i16_exit(rc);
+		while (1);
+	);
+}
+
+void (*real_exit)(int rc) = raw_exit;
+
diff --git a/i386/pc/i16/raw_real_int.c b/i386/pc/i16/raw_real_int.c
new file mode 100644
index 0000000..a76d8ca
--- /dev/null
+++ b/i386/pc/i16/raw_real_int.c
@@ -0,0 +1,46 @@
+/* 
+ * Copyright (c) 1995-1994 The University of Utah and
+ * the Computer Systems Laboratory at the University of Utah (CSL).
+ * All rights reserved.
+ *
+ * Permission to use, copy, modify and distribute this software is hereby
+ * granted provided that (1) source code retains these copyright, permission,
+ * and disclaimer notices, and (2) redistributions including binaries
+ * reproduce the notices in supporting documentation, and (3) all advertising
+ * materials mentioning features or use of this software display the following
+ * acknowledgement: ``This product includes software developed by the
+ * Computer Systems Laboratory at the University of Utah.''
+ *
+ * THE UNIVERSITY OF UTAH AND CSL ALLOW FREE USE OF THIS SOFTWARE IN ITS "AS
+ * IS" CONDITION.  THE UNIVERSITY OF UTAH AND CSL DISCLAIM ANY LIABILITY OF
+ * ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ *
+ * CSL requests users of this software to return to csl-dist@cs.utah.edu any
+ * improvements that they make and grant CSL redistribution rights.
+ *
+ *      Author: Bryan Ford, University of Utah CSL
+ */
+
+#include <mach/machine/seg.h>
+#include <mach/machine/proc_reg.h>
+
+#include "real.h"
+#include "i16.h"
+#include "debug.h"
+
+
+void raw_real_int(int intnum, struct real_call_data *rcd)
+{
+	assert((get_cs() & 3) == 0);
+
+	do_16bit(
+		unsigned int eflags;
+
+		i16_raw_switch_to_real_mode();
+		i16_real_int(intnum, rcd);
+		i16_raw_switch_to_pmode();
+	);
+}
+
+void (*real_int)(int intnum, struct real_call_data *rcd) = raw_real_int;
+
diff --git a/i386/pc/ipl.h b/i386/pc/ipl.h
new file mode 100644
index 0000000..5f40660
--- /dev/null
+++ b/i386/pc/ipl.h
@@ -0,0 +1,74 @@
+/* 
+ * Mach Operating System
+ * Copyright (c) 1991,1990,1989 Carnegie Mellon University
+ * All Rights Reserved.
+ * 
+ * Permission to use, copy, modify and distribute this software and its
+ * documentation is hereby granted, provided that both the copyright
+ * notice and this permission notice appear in all copies of the
+ * software, derivative works or modified versions, and any portions
+ * thereof, and that both notices appear in supporting documentation.
+ * 
+ * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
+ * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
+ * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ * 
+ * Carnegie Mellon requests users of this software to return to
+ * 
+ *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
+ *  School of Computer Science
+ *  Carnegie Mellon University
+ *  Pittsburgh PA 15213-3890
+ * 
+ * any improvements or extensions that they make and grant Carnegie Mellon
+ * the rights to redistribute these changes.
+ */
+/*
+Copyright (c) 1988,1989 Prime Computer, Inc.  Natick, MA 01760
+All Rights Reserved.
+
+Permission to use, copy, modify, and distribute this
+software and its documentation for any purpose and
+without fee is hereby granted, provided that the above
+copyright notice appears in all copies and that both the
+copyright notice and this permission notice appear in
+supporting documentation, and that the name of Prime
+Computer, Inc. not be used in advertising or publicity
+pertaining to distribution of the software without
+specific, written prior permission.
+
+THIS SOFTWARE IS PROVIDED "AS IS", AND PRIME COMPUTER,
+INC. DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS
+SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.  IN
+NO EVENT SHALL PRIME COMPUTER, INC.  BE LIABLE FOR ANY
+SPECIAL, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY
+DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
+PROFITS, WHETHER IN ACTION OF CONTRACT, NEGLIGENCE, OR
+OTHER TORTIOUS ACTION, ARISING OUR OF OR IN CONNECTION
+WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+
+
+#define SPL0            0
+#define SPL1            1
+#define SPL2            2
+#define SPL3            3
+#define SPL4            4
+#define SPL5            5
+#define SPL6            6
+
+#define SPLPP           5
+#define SPLTTY          6
+#define SPLNI           6
+
+#define IPLHI           8
+#define SPL7            IPLHI
+#define SPLHI           IPLHI
+
+#ifndef	ASSEMBLER
+extern int		(*ivect[])();
+extern int		iunit[];
+extern unsigned char	intpri[];
+#endif	ASSEMBLER
+
diff --git a/i386/pc/irq.h b/i386/pc/irq.h
new file mode 100644
index 0000000..1f9da9a
--- /dev/null
+++ b/i386/pc/irq.h
@@ -0,0 +1,49 @@
+/* 
+ * Copyright (c) 1995 The University of Utah and
+ * the Computer Systems Laboratory at the University of Utah (CSL).
+ * All rights reserved.
+ *
+ * Permission to use, copy, modify and distribute this software is hereby
+ * granted provided that (1) source code retains these copyright, permission,
+ * and disclaimer notices, and (2) redistributions including binaries
+ * reproduce the notices in supporting documentation, and (3) all advertising
+ * materials mentioning features or use of this software display the following
+ * acknowledgement: ``This product includes software developed by the
+ * Computer Systems Laboratory at the University of Utah.''
+ *
+ * THE UNIVERSITY OF UTAH AND CSL ALLOW FREE USE OF THIS SOFTWARE IN ITS "AS
+ * IS" CONDITION.  THE UNIVERSITY OF UTAH AND CSL DISCLAIM ANY LIABILITY OF
+ * ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ *
+ * CSL requests users of this software to return to csl-dist@cs.utah.edu any
+ * improvements that they make and grant CSL redistribution rights.
+ *
+ *      Author: Bryan Ford, University of Utah CSL
+ */
+#ifndef _I386_PC_IRQ_H_
+#define _I386_PC_IRQ_H_
+
+/* On normal PCs, there are always 16 IRQ lines.  */
+#define IRQ_COUNT 16
+
+/* Start of hardware interrupt vectors in the IDT.  */
+#define IDT_IRQ_BASE 0x20
+
+/* Variables storing the master and slave PIC interrupt vector base.  */
+extern int irq_master_base, irq_slave_base;
+
+/* Routine called just after entering protected mode for the first time,
+   to set up the IRQ interrupt vectors in the protected-mode IDT.
+   It should initialize IDT entries irq_master_base through irq_master_base+7,
+   and irq_slave_base through irq_slave_base+7.  */
+extern void idt_irq_init(void);
+
+/* Fill an IRQ gate in a CPU's IDT.
+   Always uses an interrupt gate; just set `access' to the privilege level.  */
+#define fill_irq_gate(cpu, irq_num, entry, selector, access)			\
+	fill_idt_gate(cpu, (irq_num) < 8					\
+			   ? irq_master_base+(irq_num)				\
+			   : irq_slave_base+(irq_num)-8,			\
+		  entry, selector, ACC_INTR_GATE | (access))
+
+#endif _I386_PC_IRQ_H_
diff --git a/i386/pc/irq_list.h b/i386/pc/irq_list.h
new file mode 100644
index 0000000..bfd216e
--- /dev/null
+++ b/i386/pc/irq_list.h
@@ -0,0 +1,43 @@
+/* 
+ * Copyright (c) 1995 The University of Utah and
+ * the Computer Systems Laboratory at the University of Utah (CSL).
+ * All rights reserved.
+ *
+ * Permission to use, copy, modify and distribute this software is hereby
+ * granted provided that (1) source code retains these copyright, permission,
+ * and disclaimer notices, and (2) redistributions including binaries
+ * reproduce the notices in supporting documentation, and (3) all advertising
+ * materials mentioning features or use of this software display the following
+ * acknowledgement: ``This product includes software developed by the
+ * Computer Systems Laboratory at the University of Utah.''
+ *
+ * THE UNIVERSITY OF UTAH AND CSL ALLOW FREE USE OF THIS SOFTWARE IN ITS "AS
+ * IS" CONDITION.  THE UNIVERSITY OF UTAH AND CSL DISCLAIM ANY LIABILITY OF
+ * ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ *
+ * CSL requests users of this software to return to csl-dist@cs.utah.edu any
+ * improvements that they make and grant CSL redistribution rights.
+ *
+ *      Author: Bryan Ford, University of Utah CSL
+ */
+
+/* This is just a handy file listing all the IRQ's on the PC, for whatever purpose... */
+
+irq(master,0,0)
+irq(master,1,1)
+irq(master,2,2)
+irq(master,3,3)
+irq(master,4,4)
+irq(master,5,5)
+irq(master,6,6)
+irq(master,7,7)
+
+irq(slave,0,8)
+irq(slave,1,9)
+irq(slave,2,10)
+irq(slave,3,11)
+irq(slave,4,12)
+irq(slave,5,13)
+irq(slave,6,14)
+irq(slave,7,15)
+
diff --git a/i386/pc/pc_asm.sym b/i386/pc/pc_asm.sym
new file mode 100644
index 0000000..e05677e
--- /dev/null
+++ b/i386/pc/pc_asm.sym
@@ -0,0 +1,42 @@
+/* 
+ * Copyright (c) 1995-1994 The University of Utah and
+ * the Computer Systems Laboratory at the University of Utah (CSL).
+ * All rights reserved.
+ *
+ * Permission to use, copy, modify and distribute this software is hereby
+ * granted provided that (1) source code retains these copyright, permission,
+ * and disclaimer notices, and (2) redistributions including binaries
+ * reproduce the notices in supporting documentation, and (3) all advertising
+ * materials mentioning features or use of this software display the following
+ * acknowledgement: ``This product includes software developed by the
+ * Computer Systems Laboratory at the University of Utah.''
+ *
+ * THE UNIVERSITY OF UTAH AND CSL ALLOW FREE USE OF THIS SOFTWARE IN ITS "AS
+ * IS" CONDITION.  THE UNIVERSITY OF UTAH AND CSL DISCLAIM ANY LIABILITY OF
+ * ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ *
+ * CSL requests users of this software to return to csl-dist@cs.utah.edu any
+ * improvements that they make and grant CSL redistribution rights.
+ *
+ *      Author: Bryan Ford, University of Utah CSL
+ */
+
+#include "real.h"
+#include "real_tss.h"
+
+offset	real_call_data	rcd	eax
+offset	real_call_data	rcd	ebx
+offset	real_call_data	rcd	ecx
+offset	real_call_data	rcd	edx
+offset	real_call_data	rcd	esi
+offset	real_call_data	rcd	edi
+offset	real_call_data	rcd	ebp
+offset	real_call_data	rcd	flags
+offset	real_call_data	rcd	ds
+offset	real_call_data	rcd	es
+offset	real_call_data	rcd	fs
+offset	real_call_data	rcd	gs
+size	real_call_data	rcd
+
+expr	REAL_TSS_SIZE
+
diff --git a/i386/pc/phys_mem.h b/i386/pc/phys_mem.h
new file mode 100644
index 0000000..558267c
--- /dev/null
+++ b/i386/pc/phys_mem.h
@@ -0,0 +1,55 @@
+/* 
+ * Copyright (c) 1995 The University of Utah and
+ * the Computer Systems Laboratory at the University of Utah (CSL).
+ * All rights reserved.
+ *
+ * Permission to use, copy, modify and distribute this software is hereby
+ * granted provided that (1) source code retains these copyright, permission,
+ * and disclaimer notices, and (2) redistributions including binaries
+ * reproduce the notices in supporting documentation, and (3) all advertising
+ * materials mentioning features or use of this software display the following
+ * acknowledgement: ``This product includes software developed by the
+ * Computer Systems Laboratory at the University of Utah.''
+ *
+ * THE UNIVERSITY OF UTAH AND CSL ALLOW FREE USE OF THIS SOFTWARE IN ITS "AS
+ * IS" CONDITION.  THE UNIVERSITY OF UTAH AND CSL DISCLAIM ANY LIABILITY OF
+ * ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ *
+ * CSL requests users of this software to return to csl-dist@cs.utah.edu any
+ * improvements that they make and grant CSL redistribution rights.
+ *
+ *      Author: Bryan Ford, University of Utah CSL
+ */
+/*
+ * PC-specific flag bits and priority values
+ * for the List Memory Manager (LMM)
+ * relevant for kernels managing physical memory.
+ */
+#ifndef _I386_PC_PHYS_MEM_H_
+#define _I386_PC_PHYS_MEM_H_
+
+#include_next "phys_mem.h"
+
+/* <1MB memory is most precious, then <16MB memory, then high memory.
+   Assign priorities to each region accordingly
+   so that high memory will be used first when possible,
+   then 16MB memory, then 1MB memory.  */
+#define LMM_PRI_1MB	-2
+#define LMM_PRI_16MB	-1
+#define LMM_PRI_HIGH	0
+
+/* For memory <1MB, both LMMF_1MB and LMMF_16MB will be set.
+   For memory from 1MB to 16MB, only LMMF_16MB will be set.
+   For all memory higher than that, neither will be set.  */
+#define LMMF_1MB	0x01
+#define LMMF_16MB	0x02
+
+
+/* Call one of these routines to add a chunk of physical memory found
+   to the malloc_lmm free list.
+   It assigns the appropriate flags and priorities to the region,
+   as defined above, breaking up the region if necessary.  */
+void phys_mem_add(vm_offset_t min, vm_size_t size);
+void i16_phys_mem_add(vm_offset_t min, vm_size_t size);
+
+#endif _I386_PC_PHYS_MEM_H_
diff --git a/i386/pc/phys_mem_add.c b/i386/pc/phys_mem_add.c
new file mode 100644
index 0000000..79fd3ce
--- /dev/null
+++ b/i386/pc/phys_mem_add.c
@@ -0,0 +1,62 @@
+/* 
+ * Copyright (c) 1995 The University of Utah and
+ * the Computer Systems Laboratory at the University of Utah (CSL).
+ * All rights reserved.
+ *
+ * Permission to use, copy, modify and distribute this software is hereby
+ * granted provided that (1) source code retains these copyright, permission,
+ * and disclaimer notices, and (2) redistributions including binaries
+ * reproduce the notices in supporting documentation, and (3) all advertising
+ * materials mentioning features or use of this software display the following
+ * acknowledgement: ``This product includes software developed by the
+ * Computer Systems Laboratory at the University of Utah.''
+ *
+ * THE UNIVERSITY OF UTAH AND CSL ALLOW FREE USE OF THIS SOFTWARE IN ITS "AS
+ * IS" CONDITION.  THE UNIVERSITY OF UTAH AND CSL DISCLAIM ANY LIABILITY OF
+ * ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ *
+ * CSL requests users of this software to return to csl-dist@cs.utah.edu any
+ * improvements that they make and grant CSL redistribution rights.
+ *
+ *      Author: Bryan Ford, University of Utah CSL
+ */
+
+#include <mach/machine/vm_types.h>
+#include <mach/lmm.h>
+#include <malloc.h>
+
+#include "vm_param.h"
+#include "phys_mem.h"
+
+/* Note that this routine takes _physical_ addresses, not virtual.  */
+void phys_mem_add(vm_offset_t min, vm_size_t size)
+{
+	vm_offset_t max = min + size;
+
+	/* Add the memory region with the proper flags and priority.  */
+	if (max <= 1*1024*1024)
+	{
+		lmm_add(&malloc_lmm, phystokv(min), size,
+			LMMF_1MB | LMMF_16MB, LMM_PRI_1MB);
+	}
+	else
+	{
+		if (min < 16*1024*1024)
+		{
+			vm_offset_t nmax = max;
+			if (nmax > 16*1024*1024) nmax = 16*1024*1024;
+			lmm_add(&malloc_lmm, phystokv(min), nmax - min,
+				LMMF_16MB, LMM_PRI_16MB);
+		}
+		if (max > 16*1024*1024)
+		{
+			vm_offset_t nmin = min;
+			if (nmin < 16*1024*1024) nmin = 16*1024*1024;
+			lmm_add(&malloc_lmm, phystokv(nmin), max - nmin, 0, 0);
+		}
+	}
+
+	if (max > phys_mem_max)
+		phys_mem_max = max;
+}
+
diff --git a/i386/pc/pic.c b/i386/pc/pic.c
new file mode 100644
index 0000000..eaf7b56
--- /dev/null
+++ b/i386/pc/pic.c
@@ -0,0 +1,283 @@
+/* 
+ * Mach Operating System
+ * Copyright (c) 1991,1990,1989 Carnegie Mellon University
+ * All Rights Reserved.
+ * 
+ * Permission to use, copy, modify and distribute this software and its
+ * documentation is hereby granted, provided that both the copyright
+ * notice and this permission notice appear in all copies of the
+ * software, derivative works or modified versions, and any portions
+ * thereof, and that both notices appear in supporting documentation.
+ * 
+ * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
+ * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
+ * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ * 
+ * Carnegie Mellon requests users of this software to return to
+ * 
+ *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
+ *  School of Computer Science
+ *  Carnegie Mellon University
+ *  Pittsburgh PA 15213-3890
+ * 
+ * any improvements or extensions that they make and grant Carnegie Mellon
+ * the rights to redistribute these changes.
+ */
+/*
+Copyright (c) 1988,1989 Prime Computer, Inc.  Natick, MA 01760
+All Rights Reserved.
+
+Permission to use, copy, modify, and distribute this
+software and its documentation for any purpose and
+without fee is hereby granted, provided that the above
+copyright notice appears in all copies and that both the
+copyright notice and this permission notice appear in
+supporting documentation, and that the name of Prime
+Computer, Inc. not be used in advertising or publicity
+pertaining to distribution of the software without
+specific, written prior permission.
+
+THIS SOFTWARE IS PROVIDED "AS IS", AND PRIME COMPUTER,
+INC. DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS
+SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.  IN
+NO EVENT SHALL PRIME COMPUTER, INC.  BE LIABLE FOR ANY
+SPECIAL, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY
+DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
+PROFITS, WHETHER IN ACTION OF CONTRACT, NEGLIGENCE, OR
+OTHER TORTIOUS ACTION, ARISING OUR OF OR IN CONNECTION
+WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+
+#include <mach/machine/pio.h>
+
+#include <sys/types.h>
+
+#include "ipl.h"
+#include "pic.h"
+
+
+u_short pic_mask[SPLHI+1];
+
+int		curr_ipl;
+u_short		curr_pic_mask;
+
+u_short		orig_pic_mask;
+int		orig_pic_mask_initialized;
+
+u_char intpri[NINTR];
+
+/*
+** picinit() - This routine 
+**		* Establishes a table of interrupt vectors
+**		* Establishes a table of interrupt priority levels
+**		* Establishes a table of interrupt masks to be put
+**			in the PICs.
+**		* Establishes location of PICs in the system 
+**		* Initialises them
+**
+**	At this stage the interrupt functionality of this system should be 
+**	coplete.
+**
+*/
+
+
+/*
+** 1. First we form a table of PIC masks - rather then calling form_pic_mask()
+**	each time there is a change of interrupt level - we will form a table
+**	of pic masks, as there are only 7 interrupt priority levels.
+**
+** 2. The next thing we must do is to determine which of the PIC interrupt
+**	request lines have to be masked out, this is done by calling 
+**	form_pic_mask() with a (int_lev) of zero, this will find all the 
+**	interrupt lines that have priority 0, (ie to be ignored).
+**	Then we split this up for the master/slave PICs.
+**
+** 2. Initialise the PICs , master first, then the slave.
+**	All the register field definitions are described in pic_jh.h, also
+**	the settings of these fields for the various registers are selected.
+**
+*/
+
+pic_init(int master_base, int slave_base)
+{
+	u_short PICM_OCW1, PICS_OCW1 ;
+	u_short PICM_OCW2, PICS_OCW2 ;
+	u_short PICM_OCW3, PICS_OCW3 ;
+	u_short i;
+
+	if (!orig_pic_mask_initialized)
+	{
+		unsigned omaster, oslave;
+
+		omaster = inb(MASTER_OCW);
+		PIC_DELAY();
+		oslave = inb(SLAVES_OCW);
+		PIC_DELAY();
+
+		orig_pic_mask = omaster | (oslave << 8);
+		orig_pic_mask_initialized = 1;
+	}
+
+
+	/*
+	** 1. Form pic mask table
+	*/
+
+	form_pic_mask();
+
+	/*
+	** 1a. Select current SPL.
+	*/
+
+	curr_ipl = SPLHI;
+	curr_pic_mask = pic_mask[SPLHI];
+
+	/*
+	** 3. Select options for each ICW and each OCW for each PIC.
+	*/
+
+#if 0
+	PICM_ICW1 = (ICW_TEMPLATE | EDGE_TRIGGER | ADDR_INTRVL8
+			| CASCADE_MODE | ICW4__NEEDED);
+
+	PICS_ICW1 = (ICW_TEMPLATE | EDGE_TRIGGER | ADDR_INTRVL8
+			| CASCADE_MODE | ICW4__NEEDED);
+
+	PICM_ICW2 = master_base;
+	PICS_ICW2 = slave_base;
+
+	PICM_ICW3 = ( SLAVE_ON_IR2 );
+	PICS_ICW3 = ( I_AM_SLAVE_2 );
+
+	PICM_ICW4 = (SNF_MODE_DIS | NONBUFD_MODE | NRML_EOI_MOD
+			| I8086_EMM_MOD);
+	PICS_ICW4 = (SNF_MODE_DIS | NONBUFD_MODE | NRML_EOI_MOD
+			| I8086_EMM_MOD);
+#endif
+
+	PICM_OCW1 = (curr_pic_mask & 0x00FF);
+	PICS_OCW1 = ((curr_pic_mask & 0xFF00)>>8);
+
+	PICM_OCW2 = NON_SPEC_EOI;
+	PICS_OCW2 = NON_SPEC_EOI;
+
+	PICM_OCW3 = (OCW_TEMPLATE | READ_NEXT_RD | READ_IR_ONRD );
+	PICS_OCW3 = (OCW_TEMPLATE | READ_NEXT_RD | READ_IR_ONRD );
+
+
+	/* 
+	** 4.	Initialise master - send commands to master PIC
+	*/ 
+
+	outb ( MASTER_ICW, PICM_ICW1 );
+	PIC_DELAY();
+	outb ( MASTER_OCW, master_base );
+	PIC_DELAY();
+	outb ( MASTER_OCW, PICM_ICW3 );
+	PIC_DELAY();
+	outb ( MASTER_OCW, PICM_ICW4 );
+	PIC_DELAY();
+
+#if 0
+	outb ( MASTER_OCW, PICM_MASK );
+	PIC_DELAY();
+	outb ( MASTER_ICW, PICM_OCW3 );
+	PIC_DELAY();
+#endif
+
+	/*
+	** 5.	Initialise slave - send commands to slave PIC
+	*/
+
+	outb ( SLAVES_ICW, PICS_ICW1 );
+	PIC_DELAY();
+	outb ( SLAVES_OCW, slave_base );
+	PIC_DELAY();
+	outb ( SLAVES_OCW, PICS_ICW3 );
+	PIC_DELAY();
+	outb ( SLAVES_OCW, PICS_ICW4 );
+	PIC_DELAY();
+
+#if 0
+	outb ( SLAVES_OCW, PICS_OCW1 );
+	PIC_DELAY();
+	outb ( SLAVES_ICW, PICS_OCW3 );
+	PIC_DELAY();
+
+	/*
+	** 6. Initialise interrupts
+	*/
+	outb ( MASTER_OCW, PICM_OCW1 );
+	PIC_DELAY();
+#endif
+
+	outb(MASTER_OCW, orig_pic_mask);
+	PIC_DELAY();
+	outb(SLAVES_OCW, orig_pic_mask >> 8);
+	PIC_DELAY();
+
+#if 0
+	/* XXX */
+	if (master_base != 8)
+	{
+		outb(0x21, 0xff);
+		PIC_DELAY();
+		outb(0xa1, 0xff);
+		PIC_DELAY();
+	}
+#endif
+
+	outb(MASTER_ICW, NON_SPEC_EOI);
+	PIC_DELAY();
+	outb(SLAVES_ICW, NON_SPEC_EOI);
+	PIC_DELAY();
+
+	inb(0x60);
+
+}
+
+/*
+** form_pic_mask(int_lvl) 
+**
+**	For a given interrupt priority level (int_lvl), this routine goes out 
+** and scans through the interrupt level table, and forms a mask based on the
+** entries it finds there that have the same or lower interrupt priority level
+** as (int_lvl). It returns a 16-bit mask which will have to be split up between
+** the 2 pics.
+**
+*/
+
+#define SLAVEMASK       (0xFFFF ^ SLAVE_ON_IR2)
+#define SLAVEACTV	0xFF00
+
+form_pic_mask()
+{
+	unsigned short i, j, bit, mask;
+
+	for (i=SPL0; i <= SPLHI; i++) {
+	 	for (j=0x00, bit=0x01, mask = 0; j < NINTR; j++, bit<<=1)
+			if (intpri[j] <= i)
+				mask |= bit;
+
+	 	if ((mask & SLAVEACTV) != SLAVEACTV )	
+			mask &= SLAVEMASK;
+
+		pic_mask[i] = mask;
+	}
+}
+
+#if 0
+
+intnull(unit_dev)
+{
+	printf("intnull(%d)\n", unit_dev);
+}
+
+int prtnull_count = 0;
+prtnull(unit)
+{
+	++prtnull_count;
+}
+
+#endif 0
diff --git a/i386/pc/pic.h b/i386/pc/pic.h
new file mode 100644
index 0000000..51911cc
--- /dev/null
+++ b/i386/pc/pic.h
@@ -0,0 +1,204 @@
+/* 
+ * Mach Operating System
+ * Copyright (c) 1991,1990,1989 Carnegie Mellon University
+ * All Rights Reserved.
+ * 
+ * Permission to use, copy, modify and distribute this software and its
+ * documentation is hereby granted, provided that both the copyright
+ * notice and this permission notice appear in all copies of the
+ * software, derivative works or modified versions, and any portions
+ * thereof, and that both notices appear in supporting documentation.
+ * 
+ * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
+ * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
+ * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ * 
+ * Carnegie Mellon requests users of this software to return to
+ * 
+ *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
+ *  School of Computer Science
+ *  Carnegie Mellon University
+ *  Pittsburgh PA 15213-3890
+ * 
+ * any improvements or extensions that they make and grant Carnegie Mellon
+ * the rights to redistribute these changes.
+ */
+/*
+Copyright (c) 1988,1989 Prime Computer, Inc.  Natick, MA 01760
+All Rights Reserved.
+
+Permission to use, copy, modify, and distribute this
+software and its documentation for any purpose and
+without fee is hereby granted, provided that the above
+copyright notice appears in all copies and that both the
+copyright notice and this permission notice appear in
+supporting documentation, and that the name of Prime
+Computer, Inc. not be used in advertising or publicity
+pertaining to distribution of the software without
+specific, written prior permission.
+
+THIS SOFTWARE IS PROVIDED "AS IS", AND PRIME COMPUTER,
+INC. DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS
+SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.  IN
+NO EVENT SHALL PRIME COMPUTER, INC.  BE LIABLE FOR ANY
+SPECIAL, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY
+DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
+PROFITS, WHETHER IN ACTION OF CONTRACT, NEGLIGENCE, OR
+OTHER TORTIOUS ACTION, ARISING OUR OF OR IN CONNECTION
+WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+
+#ifndef	_I386_PIC_H_
+#define	_I386_PIC_H_
+
+#include "irq.h"
+
+#define NINTR	0x10
+#define	NPICS	0x02
+
+/*
+** The following are definitions used to locate the PICs in the system
+*/
+
+#define ADDR_PIC_BASE		0x20
+#define OFF_ICW			0x00
+#define OFF_OCW			0x01
+#define SIZE_PIC		0x80
+
+#define MASTER_ICW		(ADDR_PIC_BASE + OFF_ICW)
+#define MASTER_OCW		(ADDR_PIC_BASE + OFF_OCW)
+#define SLAVES_ICW		(ADDR_PIC_BASE + OFF_ICW + SIZE_PIC)
+#define SLAVES_OCW		(ADDR_PIC_BASE + OFF_OCW + SIZE_PIC)
+
+/*
+** The following banks of definitions ICW1, ICW2, ICW3, and ICW4 are used
+** to define the fields of the various ICWs for initialisation of the PICs 
+*/
+
+/*
+**	ICW1				
+*/
+
+#define ICW_TEMPLATE		0x10
+
+#define LEVL_TRIGGER		0x08
+#define EDGE_TRIGGER		0x00
+#define ADDR_INTRVL4		0x04
+#define ADDR_INTRVL8		0x00
+#define SINGLE__MODE		0x02
+#define CASCADE_MODE		0x00
+#define ICW4__NEEDED		0x01
+#define NO_ICW4_NEED		0x00
+
+/*
+**	ICW2
+*/
+
+#define	PICM_VECTBASE		IDT_IRQ_BASE
+#define PICS_VECTBASE		(PICM_VECTBASE + 0x08)
+
+/*
+**	ICW3				
+*/
+
+#define SLAVE_ON_IR0		0x01
+#define SLAVE_ON_IR1		0x02
+#define SLAVE_ON_IR2		0x04
+#define SLAVE_ON_IR3		0x08
+#define SLAVE_ON_IR4		0x10
+#define SLAVE_ON_IR5		0x20
+#define SLAVE_ON_IR6		0x40
+#define SLAVE_ON_IR7		0x80
+
+#define I_AM_SLAVE_0		0x00
+#define I_AM_SLAVE_1		0x01
+#define I_AM_SLAVE_2		0x02
+#define I_AM_SLAVE_3		0x03
+#define I_AM_SLAVE_4		0x04
+#define I_AM_SLAVE_5		0x05
+#define I_AM_SLAVE_6		0x06
+#define I_AM_SLAVE_7		0x07
+
+/*
+**	ICW4				
+*/
+
+#define SNF_MODE_ENA		0x10
+#define SNF_MODE_DIS		0x00
+#define BUFFERD_MODE		0x08
+#define NONBUFD_MODE		0x00
+#define AUTO_EOI_MOD		0x02
+#define NRML_EOI_MOD		0x00
+#define I8086_EMM_MOD		0x01
+#define SET_MCS_MODE		0x00
+
+/*
+**	OCW1				
+*/
+
+#define PICM_MASK		0xFF
+#define	PICS_MASK		0xFF
+
+/*
+**	OCW2				
+*/
+
+#define NON_SPEC_EOI		0x20
+#define SPECIFIC_EOI		0x30
+#define ROT_NON_SPEC		0x50
+#define SET_ROT_AEOI		0x40
+#define RSET_ROTAEOI		0x00
+#define ROT_SPEC_EOI		0x70
+#define SET_PRIORITY		0x60
+#define NO_OPERATION		0x20
+
+#define SEND_EOI_IR0		0x00
+#define SEND_EOI_IR1		0x01
+#define SEND_EOI_IR2		0x02
+#define SEND_EOI_IR3		0x03
+#define SEND_EOI_IR4		0x04
+#define SEND_EOI_IR5		0x05
+#define SEND_EOI_IR6		0x06
+#define SEND_EOI_IR7		0x07
+ 
+/*
+**	OCW3				
+*/
+
+#define OCW_TEMPLATE		0x08
+#define SPECIAL_MASK		0x40
+#define MASK_MDE_SET		0x20
+#define MASK_MDE_RST		0x00
+#define POLL_COMMAND		0x04
+#define NO_POLL_CMND		0x00
+#define READ_NEXT_RD		0x02
+#define READ_IR_ONRD		0x00
+#define READ_IS_ONRD		0x01
+
+
+/*
+**	Standard PIC initialization values for PCs.
+*/
+#define PICM_ICW1	(ICW_TEMPLATE | EDGE_TRIGGER | ADDR_INTRVL8 \
+			 | CASCADE_MODE | ICW4__NEEDED)
+#define PICM_ICW3	(SLAVE_ON_IR2)
+#define PICM_ICW4	(SNF_MODE_DIS | NONBUFD_MODE | NRML_EOI_MOD \
+			 | I8086_EMM_MOD)
+
+#define PICS_ICW1	(ICW_TEMPLATE | EDGE_TRIGGER | ADDR_INTRVL8 \
+			 | CASCADE_MODE | ICW4__NEEDED)
+#define PICS_ICW3	(I_AM_SLAVE_2)
+#define PICS_ICW4	(SNF_MODE_DIS | NONBUFD_MODE | NRML_EOI_MOD \
+			 | I8086_EMM_MOD)
+
+/* Some systems need a little bit of delay
+   while fiddling with PIC registers.  */
+#ifndef ASSEMBLER
+#define PIC_DELAY() asm volatile("jmp 1f; 1: jmp 1f; 1:")
+#else
+#define PIC_DELAY jmp 9f; 9: jmp 9f; 9:
+#endif
+
+
+#endif	_I386_PIC_H_
diff --git a/i386/pc/putchar.c b/i386/pc/putchar.c
new file mode 100644
index 0000000..d5b106c
--- /dev/null
+++ b/i386/pc/putchar.c
@@ -0,0 +1,96 @@
+/* 
+ * Copyright (c) 1995-1994 The University of Utah and
+ * the Computer Systems Laboratory at the University of Utah (CSL).
+ * All rights reserved.
+ *
+ * Permission to use, copy, modify and distribute this software is hereby
+ * granted provided that (1) source code retains these copyright, permission,
+ * and disclaimer notices, and (2) redistributions including binaries
+ * reproduce the notices in supporting documentation, and (3) all advertising
+ * materials mentioning features or use of this software display the following
+ * acknowledgement: ``This product includes software developed by the
+ * Computer Systems Laboratory at the University of Utah.''
+ *
+ * THE UNIVERSITY OF UTAH AND CSL ALLOW FREE USE OF THIS SOFTWARE IN ITS "AS
+ * IS" CONDITION.  THE UNIVERSITY OF UTAH AND CSL DISCLAIM ANY LIABILITY OF
+ * ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ *
+ * CSL requests users of this software to return to csl-dist@cs.utah.edu any
+ * improvements that they make and grant CSL redistribution rights.
+ *
+ *      Author: Bryan Ford, University of Utah CSL
+ */
+
+#include <mach/machine/eflags.h>
+
+#include "real.h"
+
+#ifndef ENABLE_IMMCONSOLE
+
+#include <rc.h>
+int putchar(int c)
+{
+
+	if (c == '\n')
+		putchar('\r');
+
+	{
+#if RCLINE >= 0
+		static int serial_inited = 0;
+		if (! serial_inited) {
+			init_serial();
+			serial_inited = 1;
+		}
+		serial_putc(c);
+#else
+		struct real_call_data rcd;
+		rcd.eax = 0x0e00 | (c & 0xff);
+		rcd.ebx = 0x07;
+		rcd.flags = 0;
+		real_int(0x10, &rcd);
+#endif
+	}
+
+	return 0;
+}
+
+#else ENABLE_IMMCONSOLE
+
+void
+putchar(unsigned char c)
+{
+	static int ofs = -1;
+
+	if (ofs < 0)
+	{
+		ofs = 0;
+		putchar('\n');
+	}
+	if (c == '\r')
+	{
+		ofs = 0;
+	}
+	else if (c == '\n')
+	{
+		bcopy(0xb8000+80*2, 0xb8000, 80*2*24);
+		bzero(0xb8000+80*2*24, 80*2);
+		ofs = 0;
+	}
+	else
+	{
+		volatile unsigned char *p;
+
+		if (ofs >= 80)
+		{
+			putchar('\r');
+			putchar('\n');
+		}
+
+		p = (void*)0xb8000 + 80*2*24 + ofs*2;
+		p[0] = c;
+		p[1] = 0x0f;
+		ofs++;
+	}
+}
+
+#endif ENABLE_IMMCONSOLE
diff --git a/i386/pc/real.h b/i386/pc/real.h
new file mode 100644
index 0000000..4206231
--- /dev/null
+++ b/i386/pc/real.h
@@ -0,0 +1,60 @@
+/* 
+ * Copyright (c) 1995-1994 The University of Utah and
+ * the Computer Systems Laboratory at the University of Utah (CSL).
+ * All rights reserved.
+ *
+ * Permission to use, copy, modify and distribute this software is hereby
+ * granted provided that (1) source code retains these copyright, permission,
+ * and disclaimer notices, and (2) redistributions including binaries
+ * reproduce the notices in supporting documentation, and (3) all advertising
+ * materials mentioning features or use of this software display the following
+ * acknowledgement: ``This product includes software developed by the
+ * Computer Systems Laboratory at the University of Utah.''
+ *
+ * THE UNIVERSITY OF UTAH AND CSL ALLOW FREE USE OF THIS SOFTWARE IN ITS "AS
+ * IS" CONDITION.  THE UNIVERSITY OF UTAH AND CSL DISCLAIM ANY LIABILITY OF
+ * ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ *
+ * CSL requests users of this software to return to csl-dist@cs.utah.edu any
+ * improvements that they make and grant CSL redistribution rights.
+ *
+ *      Author: Bryan Ford, University of Utah CSL
+ */
+#ifndef _I386_PC_REAL_CALL_H_
+#define _I386_PC_REAL_CALL_H_
+
+/* This structure happens to correspond to the DPMI real-call structure.  */
+struct real_call_data
+{
+	unsigned edi;
+	unsigned esi;
+	unsigned ebp;
+	unsigned reserved;
+	unsigned ebx;
+	unsigned edx;
+	unsigned ecx;
+	unsigned eax;
+	unsigned short flags;
+	unsigned short es;
+	unsigned short ds;
+	unsigned short fs;
+	unsigned short gs;
+	unsigned short ip;
+	unsigned short cs;
+	unsigned short sp;
+	unsigned short ss;
+};
+
+/* Code segment we originally had when we started in real mode.  */
+extern unsigned short real_cs;
+
+extern void (*real_int)(int intnum, struct real_call_data *rcd);
+extern void (*real_exit)(int rc);
+
+#define real_call_data_init(rcd)	\
+	({ (rcd)->flags = 0;		\
+	   (rcd)->ss = 0;		\
+	   (rcd)->sp = 0;		\
+	})
+
+#endif /* _I386_PC_REAL_CALL_H_ */
diff --git a/i386/pc/real_tss.c b/i386/pc/real_tss.c
new file mode 100644
index 0000000..745a611
--- /dev/null
+++ b/i386/pc/real_tss.c
@@ -0,0 +1,59 @@
+/* 
+ * Copyright (c) 1995-1994 The University of Utah and
+ * the Computer Systems Laboratory at the University of Utah (CSL).
+ * All rights reserved.
+ *
+ * Permission to use, copy, modify and distribute this software is hereby
+ * granted provided that (1) source code retains these copyright, permission,
+ * and disclaimer notices, and (2) redistributions including binaries
+ * reproduce the notices in supporting documentation, and (3) all advertising
+ * materials mentioning features or use of this software display the following
+ * acknowledgement: ``This product includes software developed by the
+ * Computer Systems Laboratory at the University of Utah.''
+ *
+ * THE UNIVERSITY OF UTAH AND CSL ALLOW FREE USE OF THIS SOFTWARE IN ITS "AS
+ * IS" CONDITION.  THE UNIVERSITY OF UTAH AND CSL DISCLAIM ANY LIABILITY OF
+ * ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ *
+ * CSL requests users of this software to return to csl-dist@cs.utah.edu any
+ * improvements that they make and grant CSL redistribution rights.
+ *
+ *      Author: Bryan Ford, University of Utah CSL
+ */
+
+#include <mach/machine/tss.h>
+#include <mach/machine/proc_reg.h>
+
+#include "cpu.h"
+#include "real_tss.h"
+#include "vm_param.h"
+#include "config.h"
+
+#ifdef ENABLE_REAL_TSS
+
+static void real_tss_init()
+{
+	/* Only initialize once.  */
+	if (!real_tss.ss0)
+	{
+		/* Initialize the real-mode TSS.  */
+		real_tss.ss0 = KERNEL_DS;
+		real_tss.esp0 = get_esp();
+		real_tss.io_bit_map_offset = sizeof(real_tss);
+
+		/* Set the last byte in the I/O bitmap to all 1's.  */
+		((unsigned char*)&real_tss)[REAL_TSS_SIZE] = 0xff;
+	}
+}
+
+void
+cpu_gdt_init_REAL_TSS(struct cpu *cpu)
+{
+	real_tss_init();
+
+	fill_gdt_descriptor(cpu, REAL_TSS,
+			    kvtolin(&real_tss), REAL_TSS_SIZE-1,
+			    ACC_PL_K|ACC_TSS, 0);
+}
+
+#endif ENABLE_REAL_TSS
diff --git a/i386/pc/real_tss.h b/i386/pc/real_tss.h
new file mode 100644
index 0000000..2f89547
--- /dev/null
+++ b/i386/pc/real_tss.h
@@ -0,0 +1,34 @@
+/* 
+ * Copyright (c) 1995-1994 The University of Utah and
+ * the Computer Systems Laboratory at the University of Utah (CSL).
+ * All rights reserved.
+ *
+ * Permission to use, copy, modify and distribute this software is hereby
+ * granted provided that (1) source code retains these copyright, permission,
+ * and disclaimer notices, and (2) redistributions including binaries
+ * reproduce the notices in supporting documentation, and (3) all advertising
+ * materials mentioning features or use of this software display the following
+ * acknowledgement: ``This product includes software developed by the
+ * Computer Systems Laboratory at the University of Utah.''
+ *
+ * THE UNIVERSITY OF UTAH AND CSL ALLOW FREE USE OF THIS SOFTWARE IN ITS "AS
+ * IS" CONDITION.  THE UNIVERSITY OF UTAH AND CSL DISCLAIM ANY LIABILITY OF
+ * ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ *
+ * CSL requests users of this software to return to csl-dist@cs.utah.edu any
+ * improvements that they make and grant CSL redistribution rights.
+ *
+ *      Author: Bryan Ford, University of Utah CSL
+ */
+#ifndef _I386_PC_REAL_TSS_
+#define _I386_PC_REAL_TSS_
+
+#include <mach/machine/tss.h>
+
+extern struct i386_tss real_tss;
+
+/* This size doesn't include the extra required 0xff byte
+   just past the end of the real IOPB.  */
+#define REAL_TSS_SIZE (sizeof(real_tss)+65536/8)
+
+#endif _I386_PC_REAL_TSS_
diff --git a/i386/pc/real_tss_def.S b/i386/pc/real_tss_def.S
new file mode 100644
index 0000000..1871250
--- /dev/null
+++ b/i386/pc/real_tss_def.S
@@ -0,0 +1,35 @@
+/* 
+ * Copyright (c) 1995-1994 The University of Utah and
+ * the Computer Systems Laboratory at the University of Utah (CSL).
+ * All rights reserved.
+ *
+ * Permission to use, copy, modify and distribute this software is hereby
+ * granted provided that (1) source code retains these copyright, permission,
+ * and disclaimer notices, and (2) redistributions including binaries
+ * reproduce the notices in supporting documentation, and (3) all advertising
+ * materials mentioning features or use of this software display the following
+ * acknowledgement: ``This product includes software developed by the
+ * Computer Systems Laboratory at the University of Utah.''
+ *
+ * THE UNIVERSITY OF UTAH AND CSL ALLOW FREE USE OF THIS SOFTWARE IN ITS "AS
+ * IS" CONDITION.  THE UNIVERSITY OF UTAH AND CSL DISCLAIM ANY LIABILITY OF
+ * ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ *
+ * CSL requests users of this software to return to csl-dist@cs.utah.edu any
+ * improvements that they make and grant CSL redistribution rights.
+ *
+ *      Author: Bryan Ford, University of Utah CSL
+ */
+
+#include <mach/machine/asm.h>
+
+#include "config.h"
+#include "pc_asm.h"
+
+#ifdef ENABLE_REAL_TSS
+
+	.data
+	.globl	EXT(real_tss)
+	.comm	EXT(real_tss),REAL_TSS_SIZE+1
+
+#endif ENABLE_REAL_TSS
diff --git a/i386/pc/rv86/config.h b/i386/pc/rv86/config.h
new file mode 100644
index 0000000..5f971ce
--- /dev/null
+++ b/i386/pc/rv86/config.h
@@ -0,0 +1,29 @@
+/* 
+ * Copyright (c) 1995 The University of Utah and
+ * the Computer Systems Laboratory at the University of Utah (CSL).
+ * All rights reserved.
+ *
+ * Permission to use, copy, modify and distribute this software is hereby
+ * granted provided that (1) source code retains these copyright, permission,
+ * and disclaimer notices, and (2) redistributions including binaries
+ * reproduce the notices in supporting documentation, and (3) all advertising
+ * materials mentioning features or use of this software display the following
+ * acknowledgement: ``This product includes software developed by the
+ * Computer Systems Laboratory at the University of Utah.''
+ *
+ * THE UNIVERSITY OF UTAH AND CSL ALLOW FREE USE OF THIS SOFTWARE IN ITS "AS
+ * IS" CONDITION.  THE UNIVERSITY OF UTAH AND CSL DISCLAIM ANY LIABILITY OF
+ * ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ *
+ * CSL requests users of this software to return to csl-dist@cs.utah.edu any
+ * improvements that they make and grant CSL redistribution rights.
+ *
+ *      Author: Bryan Ford, University of Utah CSL
+ */
+
+#include_next "config.h"
+
+#ifndef ENABLE_REAL_TSS
+#define ENABLE_REAL_TSS
+#endif
+
diff --git a/i386/pc/rv86/gdt_sels.h b/i386/pc/rv86/gdt_sels.h
new file mode 100644
index 0000000..89a13c7
--- /dev/null
+++ b/i386/pc/rv86/gdt_sels.h
@@ -0,0 +1,60 @@
+/* 
+ * Copyright (c) 1995-1994 The University of Utah and
+ * the Computer Systems Laboratory at the University of Utah (CSL).
+ * All rights reserved.
+ *
+ * Permission to use, copy, modify and distribute this software is hereby
+ * granted provided that (1) source code retains these copyright, permission,
+ * and disclaimer notices, and (2) redistributions including binaries
+ * reproduce the notices in supporting documentation, and (3) all advertising
+ * materials mentioning features or use of this software display the following
+ * acknowledgement: ``This product includes software developed by the
+ * Computer Systems Laboratory at the University of Utah.''
+ *
+ * THE UNIVERSITY OF UTAH AND CSL ALLOW FREE USE OF THIS SOFTWARE IN ITS "AS
+ * IS" CONDITION.  THE UNIVERSITY OF UTAH AND CSL DISCLAIM ANY LIABILITY OF
+ * ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ *
+ * CSL requests users of this software to return to csl-dist@cs.utah.edu any
+ * improvements that they make and grant CSL redistribution rights.
+ *
+ *      Author: Bryan Ford, University of Utah CSL
+ */
+
+#include_next "gdt_sels.h"
+
+/* This is a special TSS with a full IO bitmap
+   that allows access to all I/O ports in v86 mode.
+   It's used for making calls to the real-mode BIOS (or DOS).  */
+gdt_sel(RV86_TSS)
+
+/* 
+ * Copyright (c) 1995-1994 The University of Utah and
+ * the Computer Systems Laboratory at the University of Utah (CSL).
+ * All rights reserved.
+ *
+ * Permission to use, copy, modify and distribute this software is hereby
+ * granted provided that (1) source code retains these copyright, permission,
+ * and disclaimer notices, and (2) redistributions including binaries
+ * reproduce the notices in supporting documentation, and (3) all advertising
+ * materials mentioning features or use of this software display the following
+ * acknowledgement: ``This product includes software developed by the
+ * Computer Systems Laboratory at the University of Utah.''
+ *
+ * THE UNIVERSITY OF UTAH AND CSL ALLOW FREE USE OF THIS SOFTWARE IN ITS "AS
+ * IS" CONDITION.  THE UNIVERSITY OF UTAH AND CSL DISCLAIM ANY LIABILITY OF
+ * ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ *
+ * CSL requests users of this software to return to csl-dist@cs.utah.edu any
+ * improvements that they make and grant CSL redistribution rights.
+ *
+ *      Author: Bryan Ford, University of Utah CSL
+ */
+
+#include_next "gdt_sels.h"
+
+/* This is a special TSS with a full IO bitmap
+   that allows access to all I/O ports in v86 mode.
+   It's used for making calls to the real-mode BIOS (or DOS).  */
+gdt_sel(RV86_TSS)
+
diff --git a/i386/pc/rv86/idt_irq_init.c b/i386/pc/rv86/idt_irq_init.c
new file mode 100644
index 0000000..f46882a
--- /dev/null
+++ b/i386/pc/rv86/idt_irq_init.c
@@ -0,0 +1,40 @@
+/* 
+ * Copyright (c) 1995 The University of Utah and
+ * the Computer Systems Laboratory at the University of Utah (CSL).
+ * All rights reserved.
+ *
+ * Permission to use, copy, modify and distribute this software is hereby
+ * granted provided that (1) source code retains these copyright, permission,
+ * and disclaimer notices, and (2) redistributions including binaries
+ * reproduce the notices in supporting documentation, and (3) all advertising
+ * materials mentioning features or use of this software display the following
+ * acknowledgement: ``This product includes software developed by the
+ * Computer Systems Laboratory at the University of Utah.''
+ *
+ * THE UNIVERSITY OF UTAH AND CSL ALLOW FREE USE OF THIS SOFTWARE IN ITS "AS
+ * IS" CONDITION.  THE UNIVERSITY OF UTAH AND CSL DISCLAIM ANY LIABILITY OF
+ * ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ *
+ * CSL requests users of this software to return to csl-dist@cs.utah.edu any
+ * improvements that they make and grant CSL redistribution rights.
+ *
+ *      Author: Bryan Ford, University of Utah CSL
+ */
+
+#include "cpu.h"
+#include "idt.h"
+
+void idt_irq_init()
+{
+	int i;
+
+#define irq(pic,picnum,irqnum)								\
+	{ extern void rv86_reflect_irq##irqnum();					\
+	  fill_idt_gate(&cpu[0], irq_##pic##_base + picnum,				\
+	  	(vm_offset_t)rv86_reflect_irq##irqnum, KERNEL_CS,			\
+		ACC_PL_K|ACC_INTR_GATE);						\
+	}
+#include "irq_list.h"
+#undef irq
+}
+
diff --git a/i386/pc/rv86/rv86_real_int.c b/i386/pc/rv86/rv86_real_int.c
new file mode 100644
index 0000000..d9c35b6
--- /dev/null
+++ b/i386/pc/rv86/rv86_real_int.c
@@ -0,0 +1,276 @@
+/* 
+ * Copyright (c) 1995-1994 The University of Utah and
+ * the Computer Systems Laboratory at the University of Utah (CSL).
+ * All rights reserved.
+ *
+ * Permission to use, copy, modify and distribute this software is hereby
+ * granted provided that (1) source code retains these copyright, permission,
+ * and disclaimer notices, and (2) redistributions including binaries
+ * reproduce the notices in supporting documentation, and (3) all advertising
+ * materials mentioning features or use of this software display the following
+ * acknowledgement: ``This product includes software developed by the
+ * Computer Systems Laboratory at the University of Utah.''
+ *
+ * THE UNIVERSITY OF UTAH AND CSL ALLOW FREE USE OF THIS SOFTWARE IN ITS "AS
+ * IS" CONDITION.  THE UNIVERSITY OF UTAH AND CSL DISCLAIM ANY LIABILITY OF
+ * ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ *
+ * CSL requests users of this software to return to csl-dist@cs.utah.edu any
+ * improvements that they make and grant CSL redistribution rights.
+ *
+ *      Author: Bryan Ford, University of Utah CSL
+ */
+
+#include <mach/machine/seg.h>
+#include <mach/machine/proc_reg.h>
+#include <mach/machine/far_ptr.h>
+#include <mach/machine/eflags.h>
+
+#include "vm_param.h"
+#include "real.h"
+#include "real_tss.h"
+#include "cpu.h"
+#include "debug.h"
+
+
+/*
+
+	There seem to be three main ways to handle v86 mode:
+
+	* The v86 environment is just an extension of the normal kernel environment:
+	  you can switch to and from v86 mode just as you can change any other processor state.
+	  You always keep running on the separate "logical" stack,
+	  which is the kernel stack when running in protected mode,
+	  or the user stack when running in v86 mode.
+	  When in v86 mode, the "actual" kernel stack is just a stub
+	  big enough to switch back to the "normal" kernel stack,
+	  which was being used as the user stack while running in v86 mode.
+	  Thus, v86 and protected-mode "segments" of stack data
+	  can be interleaved together on the same logical stack.
+
+		- To make a real int call from kernel pmode,
+		  switch to v86 mode and execute an int instruction,
+		  then switch back to protected mode.
+
+		- To reflect an interrupt to v86 mode:
+
+			> If the processor was running in v86 mode,
+			  just adjust the kernel and user stacks
+			  to emulate a real-mode interrupt, and return.
+
+			> If the processor was running in pmode,
+			  switch to v86 mode and re-trigger the interrupt
+			  with a software int instruction.
+
+		- To handle an interrupt in pmode:
+
+			> If the processor was running in v86 mode,
+			  switch from the stub stack to the user stack that was in use
+			  (could be different from the stack we set originally,
+			  because BIOS/DOS code might have switched stacks!),
+			  call the interrupt handler, switch back, and return.
+
+			> If the processor was running in pmode,
+			  just call the interrupt handler and return.
+
+	  This method only works if the whole "kernel" is <64KB
+	  and generally compatible with real-mode execution.
+	  This is the model my DOS extender currently uses.
+
+	  One major disadvantage of this method
+	  is that interrupt handlers can't run "general" protected-mode code,
+	  such as typical code compiled by GCC.
+	  This is because, if an interrupt occurs while in v86 mode,
+	  the v86-mode ss:sp may point basically anywhere in the low 1MB,
+	  and it therefore it can't be used directly as a pmode stack;
+	  and the only other stack available is the miniscule stub stack.
+	  Since "general" protected-mode code expects a full-size stack
+	  with an SS equal to the normal protected-mode DS,
+	  neither of these available stacks will suffice.
+	  It is impossible to switch back to the original kernel stack
+	  because arbitrary DOS or BIOS code might have switched from it
+	  to a different stack somewhere else in the low 1MB,
+	  and we have no way of telling where the SP was when that happened.
+	  The upshot is that interrupt handlers must be extremely simple;
+	  in MOSS, all they do is post a signal to "the process,"
+	  and return immediately without actually handling the interrupt.
+
+	* The v86 environment is a separate "task" with its own user and kernel stacks;
+	  you switch back and forth as if between multiple ordinary tasks,
+	  the tasks can preempt each other, go idle waiting for events, etc.
+
+		- To make a real int call from kernel pmode,
+		  the task making the call essentially does a synchronous IPC to the v86 task.
+		  If the v86 task is busy with another request or a reflected interrupt,
+		  the calling task will go idle until the v86 task is available.
+
+		- Reflecting an interrupt to v86 mode
+		  basically amounts to sending a Unix-like "signal" to the v86 task:
+
+			> If the processor was running in the v86 task,
+			  just adjust the kernel and user stacks
+			  to emulate a real-mode interrupt, and return.
+
+			> If the processor was running in a protected-mode task
+			  (or another v86-mode task),
+			  post a signal to the v86 task, wake it up if it's asleep,
+			  and invoke the scheduler to switch to the v86 task
+			  if it has a higher priority than the currently running task.
+
+		- To handle an interrupt in pmode,
+		  just call the interrupt handler and return.
+		  It doesn't matter whether the interrupt was from v86 or pmode,
+		  because the kernel stacks look the same in either case.
+
+	  One big problem with this method is that if interrupts are to be handled in v86 mode,
+	  all the typical problems of handling interrupts in user-mode tasks pop up.
+	  In particular, an interrupt can now cause preemption,
+	  so this will break an interruptible but nonpreemptible environment.
+	  (The problem is not that the interrupted task is "preempted"
+	  to switch temporarily to the v86 task to handle the interrupt;
+	  the problem is that when the v86 task is done handling the interrupt,
+	  the scheduler will be invoked and some task other than the interrupted task may be run.)
+
+	  Of course, this is undoubtedly the right solution
+	  if that's the interrupt model the OS is using anyway
+	  (i.e. if the OS already supports user-level protected-mode interrupts).
+
+	* A bastardization of the two above approaches:
+	  treat the v86 environment as a separate "task",
+	  but a special one that doesn't behave at all like other tasks.
+	  The v86 "task" in this case is more of an "interrupt co-stack"
+	  that grows and shrinks alongside the normal interrupt stack
+	  (or the current kernel stack, if interrupts are handled on the kernel stack).
+	  Interrupts and real calls can cause switches between these two interrupt stacks,
+	  but they can't cause preemption in the normal sense.
+	  The route taken while building the stacks is exactly the opposite
+	  the route taken while tearing it down.
+
+	  Now two "kernel stack pointers" have to be maintained all the time instead of one.
+	  When running in protected mode:
+
+	  	- The ESP register contains the pmode stack pointer.
+		- Some global variable contains the v86 stack pointer.
+
+	  When running in v86 mode:
+
+	  	- The ESP register contains the v86 stack pointer.
+		  (Note that BIOS/DOS code can switch stacks,
+		  so at any given time it may point practically anywhere!)
+		- The current tss's esp0 contains the pmode stack pointer.
+
+	  Whenever a switch is made, a stack frame is placed on the new co-stack
+	  indicating that the switch was performed.
+
+		- To make a real int call from kernel pmode,
+		  build a real-mode interrupt stack frame on the v86 interrupt stack,
+		  build a v86-mode trap stack frame on the pmode stack,
+		  set the tss's esp0 to point to the end of that stack frame,
+		  and iret from it.
+		  Then when the magic "done-with-real-call" int instruction is hit,
+		  the pmode interrupt handler will see it
+		  and know to simply destroy the v86 trap stack on the pmode stack.
+
+		- Handling an interrupt can always be thought of as going "through" pmode:
+		  switching from the v86 stack to the pmode stack
+		  if the processor was in v86 mode when the interrupt was taken,
+		  and switching from the pmode stack back to the v86 stack as described above
+		  if the interrupt is to be reflected to v86 mode.
+
+		  Of course, optimized paths are possible:
+
+		- To reflect an interrupt to v86 mode:
+
+			> If the processor was running in v86 mode,
+			  just adjust the kernel and user stack frames and return.
+
+			> If the processor was running in pmode,
+			  do as described above for explicit real int calls.
+
+		- To handle an interrupt in pmode:
+
+			> If the processor was running in v86 mode,
+			  switch to the pmode stack,
+			  stash the old v86 stack pointer variable on the pmode stack,
+			  and set the v86 stack pointer variable to the new location.
+			  Call the interrupt handler,
+			  then tear down everything and return to v86 mode.
+
+	Observation:
+	In the first and third models,
+	explicit real int calls are entirely symmetrical
+	to hardware interrupts from pmode to v86 mode.
+	This is valid because of the interruptible but nonpreemptible model:
+	no scheduling is involved, and the stack(s) will always be torn down
+	in exactly the opposite order in which they were built up.
+	In the second model,
+	explicit real calls are quite different,
+	because the BIOS is interruptible but nonpreemptible:
+	you can reflect an interrupt into the v86 task at any time,
+	but you can only make an explicit request to that task when it's ready
+	(i.e. no other requests or interrupts are outstanding).
+
+*/
+
+
+
+#define RV86_USTACK_SIZE 1024
+
+vm_offset_t rv86_ustack_pa;
+vm_offset_t rv86_return_int_pa;
+struct far_pointer_32 rv86_usp;
+struct far_pointer_16 rv86_rp;
+
+void rv86_real_int(int intnum, struct real_call_data *rcd)
+{
+	unsigned short old_tr;
+	unsigned int old_eflags;
+
+	/* If this is the first time this routine is being called,
+	   initialize the kernel stack.  */
+	if (!rv86_ustack_pa)
+	{
+		rv86_ustack_pa = 0xa0000 - RV86_USTACK_SIZE; /* XXX */
+
+		assert(rv86_ustack_pa < 0x100000);
+
+		/* Use the top two bytes of the ustack for an 'int $0xff' instruction.  */
+		rv86_return_int_pa = rv86_ustack_pa + RV86_USTACK_SIZE - 2;
+		*(short*)phystokv(rv86_return_int_pa) = 0xffcd;
+
+		/* Set up the v86 stack pointer.  */
+		rv86_usp.seg = rv86_rp.seg = rv86_ustack_pa >> 4;
+		rv86_usp.ofs = rv86_rp.ofs = (rv86_ustack_pa & 0xf) + RV86_USTACK_SIZE - 2;
+
+		/* Pre-allocate a real-mode interrupt stack frame.  */
+		rv86_usp.ofs -= 6;
+	}
+
+	/* Make sure interrupts are disabled.  */
+	old_eflags = get_eflags();
+
+	/* Switch to the TSS to use in v86 mode.  */
+	old_tr = get_tr();
+	cpu[0].tables.gdt[REAL_TSS_IDX].access &= ~ACC_TSS_BUSY;
+	set_tr(REAL_TSS);
+
+	asm volatile("
+		pushl	%%ebp
+		pushl	%%eax
+		call	rv86_real_int_asm
+		popl	%%eax
+		popl	%%ebp
+	" :
+	  : "a" (rcd), "S" (intnum)
+	  : "eax", "ebx", "ecx", "edx", "esi", "edi");
+
+	/* Switch to the original TSS.  */
+	cpu[0].tables.gdt[old_tr/8].access &= ~ACC_TSS_BUSY;
+	set_tr(old_tr);
+
+	/* Restore the original processor flags.  */
+	set_eflags(old_eflags);
+}
+
+void (*real_int)(int intnum, struct real_call_data *rcd) = rv86_real_int;
+
diff --git a/i386/pc/rv86/rv86_real_int_asm.S b/i386/pc/rv86/rv86_real_int_asm.S
new file mode 100644
index 0000000..54b1b9b
--- /dev/null
+++ b/i386/pc/rv86/rv86_real_int_asm.S
@@ -0,0 +1,119 @@
+/* 
+ * Copyright (c) 1995 The University of Utah and
+ * the Computer Systems Laboratory at the University of Utah (CSL).
+ * All rights reserved.
+ *
+ * Permission to use, copy, modify and distribute this software is hereby
+ * granted provided that (1) source code retains these copyright, permission,
+ * and disclaimer notices, and (2) redistributions including binaries
+ * reproduce the notices in supporting documentation, and (3) all advertising
+ * materials mentioning features or use of this software display the following
+ * acknowledgement: ``This product includes software developed by the
+ * Computer Systems Laboratory at the University of Utah.''
+ *
+ * THE UNIVERSITY OF UTAH AND CSL ALLOW FREE USE OF THIS SOFTWARE IN ITS "AS
+ * IS" CONDITION.  THE UNIVERSITY OF UTAH AND CSL DISCLAIM ANY LIABILITY OF
+ * ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ *
+ * CSL requests users of this software to return to csl-dist@cs.utah.edu any
+ * improvements that they make and grant CSL redistribution rights.
+ *
+ *      Author: Bryan Ford, University of Utah CSL
+ */
+
+#include <mach/machine/asm.h>
+#include <mach/machine/eflags.h>
+
+#include "trap.h"
+#include "i386_asm.h"
+#include "pc_asm.h"
+#include "trap_asm.h"
+
+	.text
+	.globl	rv86_real_int_asm
+rv86_real_int_asm:
+
+	/* Stash our protected-mode stack pointer.  */
+	movl	%esp,EXT(real_tss)+TSS_ESP0
+
+	/* Load the linear/physical-address data segment into ES,
+	   for easy access to real-mode memory.  */
+	movl	$LINEAR_DS,%edx
+	movw	%dx,%es
+
+	/* Find the physical address of the real-mode interrupt stack (es:ebx).
+	   A 6-byte stack frame has already been allocated on it.  */
+	movl	EXT(rv86_usp)+4,%ebx
+	shll	$4,%ebx
+	addl	EXT(rv86_usp),%ebx
+
+	/* Store the magic return pointer into the real-mode interrupt stack frame.  */
+	movl	EXT(rv86_rp),%edx
+	movl	%edx,%es:(%ebx)
+	movw	RCD_FLAGS(%eax),%dx
+	movw	%dx,%es:4(%ebx)
+
+	/* Find the address of the real mode interrupt vector (es:esi).  */
+	shll	$2,%esi
+
+	/* Build the v86 trap frame.  */
+	xorl	%edx,%edx
+	movw	RCD_GS(%eax),%dx
+	pushl	%edx
+	movw	RCD_FS(%eax),%dx
+	pushl	%edx
+	movw	RCD_DS(%eax),%dx
+	pushl	%edx
+	movw	RCD_ES(%eax),%dx
+	pushl	%edx
+	pushl	EXT(rv86_usp)+4
+	pushl	EXT(rv86_usp)
+	movl	$EFL_VM+EFL_IOPL_USER,%ecx
+	orw	RCD_FLAGS(%eax),%cx
+	andl	$-1-EFL_IF-EFL_TF,%ecx
+	pushl	%ecx
+	movw	%es:2(%esi),%edx
+	pushl	%edx
+	movw	%es:(%esi),%edx
+	pushl	%edx
+
+	/* Load the requested register state.  */
+	movl	RCD_EDI(%eax),%edi
+	movl	RCD_ESI(%eax),%esi
+	movl	RCD_EBP(%eax),%ebp
+	movl	RCD_EBX(%eax),%ebx
+	movl	RCD_EDX(%eax),%edx
+	movl	RCD_ECX(%eax),%ecx
+	movl	RCD_EAX(%eax),%eax
+
+	/* Drop into v86 mode.  */
+	iret
+
+ENTRY(rv86_return)
+
+	/* Restore the kernel segment registers.  */
+	movw	%ss,%ax
+	movw	%ax,%ds
+	movw	%ax,%es
+
+	/* Retrieve the real_call_data pointer from rv86_real_int_asm's stack frame.  */
+	movl	TR_V86SIZE+4(%esp),%eax
+
+	/* Stash the final register state.  */
+	movl	TR_EDI(%esp),%edx;	movl	%edx,RCD_EDI(%eax)
+	movl	TR_ESI(%esp),%edx;	movl	%edx,RCD_ESI(%eax)
+	movl	TR_EBP(%esp),%edx;	movl	%edx,RCD_EBP(%eax)
+	movl	TR_EBX(%esp),%edx;	movl	%edx,RCD_EBX(%eax)
+	movl	TR_EDX(%esp),%edx;	movl	%edx,RCD_EDX(%eax)
+	movl	TR_ECX(%esp),%edx;	movl	%edx,RCD_ECX(%eax)
+	movl	TR_EAX(%esp),%edx;	movl	%edx,RCD_EAX(%eax)
+	movl	TR_EFLAGS(%esp),%edx;	movw	%dx,RCD_FLAGS(%eax)
+	movl	TR_V86_ES(%esp),%edx;	movw	%dx,RCD_ES(%eax)
+	movl	TR_V86_DS(%esp),%edx;	movw	%dx,RCD_DS(%eax)
+	movl	TR_V86_FS(%esp),%edx;	movw	%dx,RCD_FS(%eax)
+	movl	TR_V86_GS(%esp),%edx;	movw	%dx,RCD_GS(%eax)
+
+	/* Return from the call to rv86_real_int_asm.  */
+	lea	TR_V86SIZE(%esp),%esp
+	ret
+
diff --git a/i386/pc/rv86/rv86_reflect_irq.S b/i386/pc/rv86/rv86_reflect_irq.S
new file mode 100644
index 0000000..5d68fae
--- /dev/null
+++ b/i386/pc/rv86/rv86_reflect_irq.S
@@ -0,0 +1,113 @@
+/* 
+ * Copyright (c) 1995 The University of Utah and
+ * the Computer Systems Laboratory at the University of Utah (CSL).
+ * All rights reserved.
+ *
+ * Permission to use, copy, modify and distribute this software is hereby
+ * granted provided that (1) source code retains these copyright, permission,
+ * and disclaimer notices, and (2) redistributions including binaries
+ * reproduce the notices in supporting documentation, and (3) all advertising
+ * materials mentioning features or use of this software display the following
+ * acknowledgement: ``This product includes software developed by the
+ * Computer Systems Laboratory at the University of Utah.''
+ *
+ * THE UNIVERSITY OF UTAH AND CSL ALLOW FREE USE OF THIS SOFTWARE IN ITS "AS
+ * IS" CONDITION.  THE UNIVERSITY OF UTAH AND CSL DISCLAIM ANY LIABILITY OF
+ * ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ *
+ * CSL requests users of this software to return to csl-dist@cs.utah.edu any
+ * improvements that they make and grant CSL redistribution rights.
+ *
+ *      Author: Bryan Ford, University of Utah CSL
+ */
+
+#include <mach/machine/asm.h>
+#include <mach/machine/eflags.h>
+
+#include "trap.h"
+#include "trap_asm.h"
+#include "pc_asm.h"
+#include "i386_asm.h"
+
+/*
+ * Define a set of interrupt handlers to reflect interrupts to v86 mode.
+ */
+
+	.text
+
+#define master_base	0x08
+#define slave_base	0x70
+
+#define irq(pic,picnum,irqnum)				\
+ENTRY(rv86_reflect_irq##irqnum)				;\
+	pushl	$pic##_base+picnum			;\
+	pushl	$0x80000000+irqnum /* (for debug) */	;\
+	jmp	allintrs
+
+#include "irq_list.h"
+
+
+allintrs:
+	pusha
+	pushl	%ds
+	pushl	%es
+	pushl	%fs
+	pushl	%gs
+
+	/* Load the normal kernel segment registers.  */
+	movw	%ss,%ax
+	movw	%ax,%ds
+	movw	%ax,%es
+
+	/* See if we came from v86 mode.  */
+	testl	$EFL_VM,TR_EFLAGS(%esp)
+	jnz	int_from_v86
+
+	movl	TR_ERR(%esp),%eax
+	pushl	$dummy_rcd
+	pushl	%eax
+	call	EXT(rv86_real_int)
+	addl	$2*4,%esp
+
+	popl	%gs
+	popl	%fs
+	popl	%es
+	popl	%ds
+	popa
+	addl	$2*4,%esp
+	iret
+
+int_from_v86:
+
+	/* Save the v86 stack pointer before handling the interrupt.
+	   We need this in order to handle recursive reflected interrupts
+	   possibly interspersed with protected-mode interrupts.  */
+	movl	EXT(rv86_usp),%esi
+	movl	EXT(rv86_usp)+4,%edi
+	movl	EXT(real_tss)+TSS_ESP0,%ebx
+
+	movl	TR_ESP(%esp),%eax
+	subw	$6,%ax	/* allocate a real-mode interrupt stack frame.  */
+	movl	%eax,EXT(rv86_usp)
+	movl	TR_SS(%esp),%eax
+	movw	%ax,EXT(rv86_usp)+4
+
+	movl	TR_ERR(%esp),%eax
+	pushl	$dummy_rcd
+	pushl	%eax
+	call	EXT(rv86_real_int)
+	addl	$2*4,%esp
+
+	movl	%esi,EXT(rv86_usp)
+	movl	%edi,EXT(rv86_usp)+4
+	movl	%ebx,EXT(real_tss)+TSS_ESP0
+
+	addl	$4*4,%esp
+	popa
+	addl	$2*4,%esp
+	iret
+
+	/* Dummy real_call_data structure (always all zero)
+	   to use when reflecting hardware interrupts.  */
+	.comm	dummy_rcd,RCD_SIZE
+
diff --git a/i386/pc/rv86/rv86_trap_handler.S b/i386/pc/rv86/rv86_trap_handler.S
new file mode 100644
index 0000000..793f6b6
--- /dev/null
+++ b/i386/pc/rv86/rv86_trap_handler.S
@@ -0,0 +1,167 @@
+/* 
+ * Copyright (c) 1995-1994 The University of Utah and
+ * the Computer Systems Laboratory at the University of Utah (CSL).
+ * All rights reserved.
+ *
+ * Permission to use, copy, modify and distribute this software is hereby
+ * granted provided that (1) source code retains these copyright, permission,
+ * and disclaimer notices, and (2) redistributions including binaries
+ * reproduce the notices in supporting documentation, and (3) all advertising
+ * materials mentioning features or use of this software display the following
+ * acknowledgement: ``This product includes software developed by the
+ * Computer Systems Laboratory at the University of Utah.''
+ *
+ * THE UNIVERSITY OF UTAH AND CSL ALLOW FREE USE OF THIS SOFTWARE IN ITS "AS
+ * IS" CONDITION.  THE UNIVERSITY OF UTAH AND CSL DISCLAIM ANY LIABILITY OF
+ * ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ *
+ * CSL requests users of this software to return to csl-dist@cs.utah.edu any
+ * improvements that they make and grant CSL redistribution rights.
+ *
+ *      Author: Bryan Ford, University of Utah CSL
+ */
+
+#include <mach/machine/asm.h>
+#include <mach/machine/eflags.h>
+
+#include "i386_asm.h"
+#include "trap.h"
+#include "trap_asm.h"
+
+	.text
+
+ENTRY(rv86_trap_handler)
+	cmpl	$T_GENERAL_PROTECTION,TR_TRAPNO(%esp)
+	jz	gpf_from_v86
+
+	UNEXPECTED_TRAP
+
+gpf_from_v86:
+
+	/* Load the linear/physical-address data segment,
+	   for easy access to real-mode memory.  */
+	movl	$LINEAR_DS,%eax
+	movw	%ax,%ds
+
+	/* Find the physical address of the trapping instruction (ebx).  */
+	movzwl	TR_CS(%esp),%ebx
+	shll	$4,%ebx
+	addl	TR_EIP(%esp),%ebx
+
+	/* See if we're just trying to get out of v86 mode.  */
+	cmpl	%ss:EXT(rv86_return_int_pa),%ebx
+	je	EXT(rv86_return)
+
+	/* Check the instruction (al).  */
+	movb	(%ebx),%al
+	cmpb	$0xcd,%al
+	je	gpf_int_n
+
+	UNEXPECTED_TRAP
+
+
+gpf_int_n:
+
+	/* Bump the ip past the int instruction.  */
+	addw	$2,TR_EIP(%esp)
+
+	/* Find the real mode interrupt vector number (esi).  */
+	movzbl	1(%ebx),%esi
+
+	/* See if it's a copy-extended-memory interrupt request;
+	   if so, just handle it here.  */
+	cmpl	$0x15,%esi
+	jne	1f
+	cmpb	$0x87,TR_EAX+1(%esp)
+	je	copy_ext_mem
+1:
+
+	/* XXX The stuff down here is essentially the same as in moss.  */
+
+reflect_v86_intr:
+
+	/* Find the address of the real mode interrupt vector (esi).  */
+	shll	$2,%esi
+
+	/* Make room for the real-mode interrupt stack frame.  */
+	subw	$6,TR_ESP(%esp)
+
+	/* Find the physical address of the v86 stack (ebx).  */
+	movzwl	TR_SS(%esp),%ebx
+	shll	$4,%ebx
+	addl	TR_ESP(%esp),%ebx
+
+	/* Store the return information into the v86 stack frame.  */
+	movl	TR_EIP(%esp),%eax
+	movw	%ax,(%ebx)
+	movl	TR_CS(%esp),%eax
+	movw	%ax,2(%ebx)
+	movl	TR_EFLAGS(%esp),%eax
+	movw	%ax,4(%ebx)
+
+	/* Find the real-mode interrupt vector to invoke,
+	   and set up the real_call_thread's kernel stack frame
+	   to point to it.  */
+	movl	(%esi),%eax
+	movw	%ax,TR_EIP(%esp)
+	shrl	$16,%eax
+	movw	%ax,TR_CS(%esp)
+	andl	$-1-EFL_IF-EFL_TF,TR_EFLAGS(%esp)
+
+	/* Restore saved state and return.  */
+	addl	$4*4,%esp
+	popa
+	addl	$4*2,%esp
+	iret
+
+
+
+/* We intercepted a copy-extended-memory software interrupt
+   (int 0x15 function 0x87).
+   This is used by HIMEM.SYS, for example, to manage extended memory.
+   The BIOS's routine isn't going to work in v86 mode,
+   so do it ourselves.  */
+copy_ext_mem:
+
+	/* Find the parameter block provided by the caller (ebx).  */
+	movzwl	TR_V86_ES(%esp),%ebx
+	movzwl	TR_ESI(%esp),%eax
+	shll	$4,%ebx
+	addl	%eax,%ebx
+
+	/* Source address (esi).  */
+	movl	0x12(%ebx),%esi
+	andl	$0x00ffffff,%esi
+
+	/* Destination address (edi).  */
+	movl	0x1a(%ebx),%edi
+	andl	$0x00ffffff,%edi
+
+	/* Number of bytes (ecx).  */
+	movzwl	TR_ECX(%esp),%ecx
+	addl	%ecx,%ecx
+
+	/* Use the standard i386 bcopy routine to copy the data.
+	   This assumes it's "friendly" in its use of segment registers
+	   (i.e. always uses ss for stack data and ds/es for the data to copy).
+	   The bcopy is simple enough that this should always be true.  */
+	movw	%ds,%ax
+	movw	%ax,%es
+	cld
+	pushl	%ecx
+	pushl	%edi
+	pushl	%esi
+	call	EXT(bcopy)
+	addl	$3*4,%esp
+
+	/* Clear the carry flag to indicate that the copy was successful.
+	   AH is also cleared, below.  */
+	andl	$-1-EFL_CF,TR_EFLAGS(%esp)
+
+	/* Restore saved state and return.  */
+	addl	$4*4,%esp
+	popa
+	xorb	%ah,%ah
+	addl	$4*2,%esp
+	iret
+
diff --git a/i386/pc/rv86/trap_handler.S b/i386/pc/rv86/trap_handler.S
new file mode 100644
index 0000000..99254ee
--- /dev/null
+++ b/i386/pc/rv86/trap_handler.S
@@ -0,0 +1,39 @@
+/* 
+ * Copyright (c) 1995-1994 The University of Utah and
+ * the Computer Systems Laboratory at the University of Utah (CSL).
+ * All rights reserved.
+ *
+ * Permission to use, copy, modify and distribute this software is hereby
+ * granted provided that (1) source code retains these copyright, permission,
+ * and disclaimer notices, and (2) redistributions including binaries
+ * reproduce the notices in supporting documentation, and (3) all advertising
+ * materials mentioning features or use of this software display the following
+ * acknowledgement: ``This product includes software developed by the
+ * Computer Systems Laboratory at the University of Utah.''
+ *
+ * THE UNIVERSITY OF UTAH AND CSL ALLOW FREE USE OF THIS SOFTWARE IN ITS "AS
+ * IS" CONDITION.  THE UNIVERSITY OF UTAH AND CSL DISCLAIM ANY LIABILITY OF
+ * ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ *
+ * CSL requests users of this software to return to csl-dist@cs.utah.edu any
+ * improvements that they make and grant CSL redistribution rights.
+ *
+ *      Author: Bryan Ford, University of Utah CSL
+ */
+
+#include <mach/machine/asm.h>
+#include <mach/machine/eflags.h>
+
+#include "trap.h"
+#include "trap_asm.h"
+
+	.text
+
+ENTRY(trap_handler)
+
+	/* See if we came from v86 mode.  */
+	testl	$EFL_VM,TR_EFLAGS(%esp)
+	jnz	EXT(rv86_trap_handler)
+
+	UNEXPECTED_TRAP
+