Initial source

1 files changed, 159 insertions, 0 deletions

diff --git a/vm/vm_external.c b/vm/vm_external.c
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index 0000000..da59137
--- /dev/null
+++ b/vm/vm_external.c
@@ -0,0 +1,159 @@
+/* 
+ * 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.
+ */
+/*
+ *	This module maintains information about the presence of
+ *	pages not in memory.  Since an external memory object
+ *	must maintain a complete knowledge of its contents, this
+ *	information takes the form of hints.
+ */
+
+#include <mach/boolean.h>
+#include <kern/zalloc.h>
+#include <vm/vm_external.h>
+#include <mach/vm_param.h>
+#include <kern/assert.h>
+
+
+
+boolean_t	vm_external_unsafe = FALSE;
+
+zone_t		vm_external_zone = ZONE_NULL;
+
+/*
+ *	The implementation uses bit arrays to record whether
+ *	a page has been written to external storage.  For
+ *	convenience, these bit arrays come in two sizes
+ *	(measured in bytes).
+ */
+
+#define		SMALL_SIZE	(VM_EXTERNAL_SMALL_SIZE/8)
+#define		LARGE_SIZE	(VM_EXTERNAL_LARGE_SIZE/8)
+
+zone_t		vm_object_small_existence_map_zone;
+zone_t		vm_object_large_existence_map_zone;
+
+
+vm_external_t	vm_external_create(size)
+	vm_offset_t	size;
+{
+	vm_external_t	result;
+	vm_size_t	bytes;
+	
+	if (vm_external_zone == ZONE_NULL)
+		return(VM_EXTERNAL_NULL);
+
+	result = (vm_external_t) zalloc(vm_external_zone);
+	result->existence_map = (char *) 0;
+
+	bytes = (atop(size) + 07) >> 3;
+	if (bytes <= SMALL_SIZE) {
+		result->existence_map =
+		 (char *) zalloc(vm_object_small_existence_map_zone);
+		result->existence_size = SMALL_SIZE;
+	} else if (bytes <= LARGE_SIZE) {
+		result->existence_map =
+		 (char *) zalloc(vm_object_large_existence_map_zone);
+		result->existence_size = LARGE_SIZE;
+	}
+	return(result);
+}
+
+void		vm_external_destroy(e)
+	vm_external_t	e;
+{
+	if (e == VM_EXTERNAL_NULL)
+		return;
+
+	if (e->existence_map != (char *) 0) {
+		if (e->existence_size <= SMALL_SIZE) {
+			zfree(vm_object_small_existence_map_zone,
+				(vm_offset_t) e->existence_map);
+		} else {
+			zfree(vm_object_large_existence_map_zone,
+				(vm_offset_t) e->existence_map);
+		}
+	}
+	zfree(vm_external_zone, (vm_offset_t) e);
+}
+
+vm_external_state_t _vm_external_state_get(e, offset)
+	vm_external_t	e;
+	vm_offset_t	offset;
+{
+	unsigned
+	int		bit, byte;
+
+	if (vm_external_unsafe ||
+	    (e == VM_EXTERNAL_NULL) ||
+	    (e->existence_map == (char *) 0))
+		return(VM_EXTERNAL_STATE_UNKNOWN);
+
+	bit = atop(offset);
+	byte = bit >> 3;
+	if (byte >= e->existence_size) return (VM_EXTERNAL_STATE_UNKNOWN);
+	return( (e->existence_map[byte] & (1 << (bit & 07))) ?
+		VM_EXTERNAL_STATE_EXISTS : VM_EXTERNAL_STATE_ABSENT );
+}
+
+void		vm_external_state_set(e, offset, state)
+	vm_external_t	e;
+	vm_offset_t	offset;
+	vm_external_state_t state;
+{
+	unsigned
+	int		bit, byte;
+
+	if ((e == VM_EXTERNAL_NULL) || (e->existence_map == (char *) 0))
+		return;
+
+	if (state != VM_EXTERNAL_STATE_EXISTS)
+		return;
+
+	bit = atop(offset);
+	byte = bit >> 3;
+	if (byte >= e->existence_size) return;
+	e->existence_map[byte] |= (1 << (bit & 07));
+}
+
+void		vm_external_module_initialize()
+{
+	vm_size_t	size = (vm_size_t) sizeof(struct vm_external);
+
+	vm_external_zone = zinit(size, 16*1024*size, size,
+				 0, "external page bitmaps");
+
+	vm_object_small_existence_map_zone = zinit(SMALL_SIZE,
+					round_page(LARGE_SIZE * SMALL_SIZE),
+					round_page(SMALL_SIZE),
+					ZONE_EXHAUSTIBLE,
+					"object small existence maps");
+
+	vm_object_large_existence_map_zone = zinit(LARGE_SIZE,
+					round_page(8 * LARGE_SIZE),
+					round_page(LARGE_SIZE),
+					ZONE_EXHAUSTIBLE,
+					"object large existence maps");
+}