projects / linux-2.6-block.git / blame
| Commit | Line | Data |
|---|---|---|
| 449f2ab9 PA |
1 | /* -*- linux-c -*- ------------------------------------------------------- * |
| 2 | * | |
| 3 | * Copyright (C) 1991, 1992 Linus Torvalds | |
| 4 | * Copyright 2007 rPath, Inc. - All Rights Reserved | |
| 5 | * | |
| 6 | * This file is part of the Linux kernel, and is made available under | |
| 7 | * the terms of the GNU General Public License version 2. | |
| 8 | * | |
| 9 | * ----------------------------------------------------------------------- */ | |
| 10 | ||
| 11 | /* | |
| 12 | * arch/i386/boot/memory.c | |
| 13 | * | |
| 14 | * Memory detection code | |
| 15 | */ | |
| 16 | ||
| 17 | #include "boot.h" | |
| 18 | ||
| 19 | #define SMAP 0x534d4150 /* ASCII "SMAP" */ | |
| 20 | ||
| 21 | static int detect_memory_e820(void) | |
| 22 | { | |
| 23 | u32 next = 0; | |
| 24 | u32 size, id; | |
| 25 | u8 err; | |
| 26 | struct e820entry *desc = boot_params.e820_map; | |
| 27 | ||
| 28 | do { | |
| 29 | size = sizeof(struct e820entry); | |
| 30 | id = SMAP; | |
| 31 | asm("int $0x15; setc %0" | |
| 32 | : "=am" (err), "+b" (next), "+d" (id), "+c" (size), | |
| 33 | "=m" (*desc) | |
| 34 | : "D" (desc), "a" (0xe820)); | |
| 35 | ||
| 36 | if (err || id != SMAP) | |
| 37 | break; | |
| 38 | ||
| 39 | boot_params.e820_entries++; | |
| 40 | desc++; | |
| 41 | } while (next && boot_params.e820_entries < E820MAX); | |
| 42 | ||
| 43 | return boot_params.e820_entries; | |
| 44 | } | |
| 45 | ||
| 46 | static int detect_memory_e801(void) | |
| 47 | { | |
| 48 | u16 ax, bx, cx, dx; | |
| 49 | u8 err; | |
| 50 | ||
| 51 | bx = cx = dx = 0; | |
| 52 | ax = 0xe801; | |
| 53 | asm("stc; int $0x15; setc %0" | |
| 54 | : "=m" (err), "+a" (ax), "+b" (bx), "+c" (cx), "+d" (dx)); | |
| 55 | ||
| 56 | if (err) | |
| 57 | return -1; | |
| 58 | ||
| 59 | /* Do we really need to do this? */ | |
| 60 | if (cx || dx) { | |
| 61 | ax = cx; | |
| 62 | bx = dx; | |
| 63 | } | |
| 64 | ||
| 65 | if (ax > 15*1024) | |
| 66 | return -1; /* Bogus! */ | |
| 67 | ||
| 68 | /* This ignores memory above 16MB if we have a memory hole | |
| 69 | there. If someone actually finds a machine with a memory | |
| 70 | hole at 16MB and no support for 0E820h they should probably | |
| 71 | generate a fake e820 map. */ | |
| 72 | boot_params.alt_mem_k = (ax == 15*1024) ? (dx << 6)+ax : ax; | |
| 73 | ||
| 74 | return 0; | |
| 75 | } | |
| 76 | ||
| 77 | static int detect_memory_88(void) | |
| 78 | { | |
| 79 | u16 ax; | |
| 80 | u8 err; | |
| 81 | ||
| 82 | ax = 0x8800; | |
| 83 | asm("stc; int $0x15; setc %0" : "=bcdm" (err), "+a" (ax)); | |
| 84 | ||
| 85 | boot_params.screen_info.ext_mem_k = ax; | |
| 86 | ||
| 87 | return -err; | |
| 88 | } | |
| 89 | ||
| 90 | int detect_memory(void) | |
| 91 | { | |
| 92 | if (detect_memory_e820() > 0) | |
| 93 | return 0; | |
| 94 | ||
| 95 | if (!detect_memory_e801()) | |
| 96 | return 0; | |
| 97 | ||
| 98 | return detect_memory_88(); | |
| 99 | } |