From f07a4c844da9f0ecae5bbee1ab94be56505f26f7 Mon Sep 17 00:00:00 2001
From: Thomas Bushnell <thomas@gnu.org>
Date: Tue, 25 Feb 1997 21:28:37 +0000
Subject: Initial source

---
 i386/i386/gdt.c | 88 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 88 insertions(+)
 create mode 100644 i386/i386/gdt.c

(limited to 'i386/i386/gdt.c')

diff --git a/i386/i386/gdt.c b/i386/i386/gdt.c
new file mode 100644
index 0000000..d855111
--- /dev/null
+++ b/i386/i386/gdt.c
@@ -0,0 +1,88 @@
+/* 
+ * Mach Operating System
+ * Copyright (c) 1991,1990 Carnegie Mellon University
+ * Copyright (c) 1991 IBM Corporation 
+ * 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,
+ * and that the name IBM not be used in advertising or publicity 
+ * pertaining to distribution of the software without specific, written
+ * prior permission.
+ * 
+ * CARNEGIE MELLON AND IBM ALLOW FREE USE OF THIS SOFTWARE IN ITS "AS IS"
+ * CONDITION.  CARNEGIE MELLON AND IBM DISCLAIM 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.
+ */
+/*
+ * Global descriptor table.
+ */
+#include <mach/machine/vm_types.h>
+
+#include <platforms.h>
+
+#include "vm_param.h"
+#include "seg.h"
+#include "gdt.h"
+
+#if     PS2
+extern unsigned long abios_int_return;
+extern unsigned long abios_th_return;
+extern char intstack[];
+#endif  /* PS2 */
+
+struct real_descriptor gdt[GDTSZ];
+
+void
+gdt_init()
+{
+	/* Initialize the kernel code and data segment descriptors.  */
+	fill_gdt_descriptor(KERNEL_CS,
+			    LINEAR_MIN_KERNEL_ADDRESS, 
+			    LINEAR_MAX_KERNEL_ADDRESS - LINEAR_MIN_KERNEL_ADDRESS - 1,
+			    ACC_PL_K|ACC_CODE_R, SZ_32);
+	fill_gdt_descriptor(KERNEL_DS,
+			    LINEAR_MIN_KERNEL_ADDRESS, 
+			    LINEAR_MAX_KERNEL_ADDRESS - LINEAR_MIN_KERNEL_ADDRESS - 1,
+			    ACC_PL_K|ACC_DATA_W, SZ_32);
+
+	/* Load the new GDT.  */
+	{
+		struct pseudo_descriptor pdesc;
+
+		pdesc.limit = sizeof(gdt)-1;
+		pdesc.linear_base = kvtolin(&gdt);
+		lgdt(&pdesc);
+	}
+
+	/* Reload all the segment registers from the new GDT.
+	   We must load ds and es with 0 before loading them with KERNEL_DS
+	   because some processors will "optimize out" the loads
+	   if the previous selector values happen to be the same.  */
+	asm volatile("
+		ljmp	%0,$1f
+	1:
+		movw	%w2,%%ds
+		movw	%w2,%%es
+		movw	%w2,%%fs
+		movw	%w2,%%gs
+
+		movw	%w1,%%ds
+		movw	%w1,%%es
+		movw	%w1,%%ss
+	" : : "i" (KERNEL_CS), "r" (KERNEL_DS), "r" (0));
+}
+
-- 
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