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-rw-r--r-- | arch/i386/boot/memory.c | 99 |
1 files changed, 99 insertions, 0 deletions
diff --git a/arch/i386/boot/memory.c b/arch/i386/boot/memory.c new file mode 100644 index 00000000000..1a2e62db8be --- /dev/null +++ b/arch/i386/boot/memory.c @@ -0,0 +1,99 @@ +/* -*- linux-c -*- ------------------------------------------------------- * + * + * Copyright (C) 1991, 1992 Linus Torvalds + * Copyright 2007 rPath, Inc. - All Rights Reserved + * + * This file is part of the Linux kernel, and is made available under + * the terms of the GNU General Public License version 2. + * + * ----------------------------------------------------------------------- */ + +/* + * arch/i386/boot/memory.c + * + * Memory detection code + */ + +#include "boot.h" + +#define SMAP 0x534d4150 /* ASCII "SMAP" */ + +static int detect_memory_e820(void) +{ + u32 next = 0; + u32 size, id; + u8 err; + struct e820entry *desc = boot_params.e820_map; + + do { + size = sizeof(struct e820entry); + id = SMAP; + asm("int $0x15; setc %0" + : "=am" (err), "+b" (next), "+d" (id), "+c" (size), + "=m" (*desc) + : "D" (desc), "a" (0xe820)); + + if (err || id != SMAP) + break; + + boot_params.e820_entries++; + desc++; + } while (next && boot_params.e820_entries < E820MAX); + + return boot_params.e820_entries; +} + +static int detect_memory_e801(void) +{ + u16 ax, bx, cx, dx; + u8 err; + + bx = cx = dx = 0; + ax = 0xe801; + asm("stc; int $0x15; setc %0" + : "=m" (err), "+a" (ax), "+b" (bx), "+c" (cx), "+d" (dx)); + + if (err) + return -1; + + /* Do we really need to do this? */ + if (cx || dx) { + ax = cx; + bx = dx; + } + + if (ax > 15*1024) + return -1; /* Bogus! */ + + /* This ignores memory above 16MB if we have a memory hole + there. If someone actually finds a machine with a memory + hole at 16MB and no support for 0E820h they should probably + generate a fake e820 map. */ + boot_params.alt_mem_k = (ax == 15*1024) ? (dx << 6)+ax : ax; + + return 0; +} + +static int detect_memory_88(void) +{ + u16 ax; + u8 err; + + ax = 0x8800; + asm("stc; int $0x15; setc %0" : "=bcdm" (err), "+a" (ax)); + + boot_params.screen_info.ext_mem_k = ax; + + return -err; +} + +int detect_memory(void) +{ + if (detect_memory_e820() > 0) + return 0; + + if (!detect_memory_e801()) + return 0; + + return detect_memory_88(); +} |