patch-2.1.110 linux/include/asm-i386/fixmap.h

• Lines: 77
• Date: Mon Jul 20 14:00:06 1998
• Orig file: v2.1.109/linux/include/asm-i386/fixmap.h
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.1.109/linux/include/asm-i386/fixmap.h linux/include/asm-i386/fixmap.h
@@ -0,0 +1,76 @@
+/*
+ * fixmap.h: compile-time virtual memory allocation
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 1998 Ingo Molnar
+ */
+
+#ifndef _ASM_FIXMAP_H
+#define _ASM_FIXMAP_H
+
+#include <asm/page.h>
+#include <linux/kernel.h>
+
+/*
+ * Here we define all the compile-time 'special' virtual
+ * addresses. The point is to have a constant address at
+ * compile time, but to set the physical address only
+ * in the boot process. We allocate these special  addresses
+ * from the end of virtual memory (0xfffff000) backwards.
+ * Also this lets us do fail-safe vmalloc(), we
+ * can guarantee that these special addresses and
+ * vmalloc()-ed addresses never overlap.
+ *
+ * these 'compile-time allocated' memory buffers are
+ * fixed-size 4k pages. (or larger if used with an increment
+ * bigger than 1) use fixmap_set(idx,phys) to associate
+ * physical memory with fixmap indices.
+ *
+ * TLB entries of such buffers will not be flushed across
+ * task switches.
+ */
+
+enum fixed_addresses {
+/*
+ * on UP currently we will have no trace of the fixmap mechanizm,
+ * no page table allocations, etc. This might change in the
+ * future, say framebuffers for the console driver(s) could be
+ * fix-mapped?
+ */
+#if __SMP__
+	FIX_APIC_BASE 			= 1,	/* 0xfffff000 */
+	FIX_IO_APIC_BASE 		= 2,	/* 0xffffe000 */
+#endif
+	__end_of_fixed_addresses
+};
+
+extern void set_fixmap (enum fixed_addresses idx, unsigned long phys);
+
+/*
+ * used by vmalloc.c:
+ */
+#define FIXADDR_START (0UL-((__end_of_fixed_addresses-1)<<PAGE_SHIFT))
+
+/*
+ * 'index to address' translation. If anyone tries to use the idx
+ * directly without tranlation, we catch the bug with a NULL-deference
+ * kernel oops. Illegal ranges of incoming indices are caught too.
+ */
+extern inline unsigned long fix_to_virt(const unsigned int idx)
+{
+	/*
+	 * this branch gets completely eliminated after inlining,
+	 * except when someone tries to use fixaddr indices in an
+	 * illegal way. (such as mixing up address types or using
+	 * out-of-range indices)
+	 */
+	if ((!idx) || (idx >= __end_of_fixed_addresses))
+		panic("illegal fixaddr index!");
+
+        return (0UL-(unsigned long)(idx<<PAGE_SHIFT));
+}
+
+#endif