diff options
Diffstat (limited to 'arch/x86/boot/memory.c')
| -rw-r--r-- | arch/x86/boot/memory.c | 39 |
1 files changed, 30 insertions, 9 deletions
diff --git a/arch/x86/boot/memory.c b/arch/x86/boot/memory.c index 8c3c25f35578..5054c2ddd1a0 100644 --- a/arch/x86/boot/memory.c +++ b/arch/x86/boot/memory.c @@ -2,6 +2,7 @@ * * Copyright (C) 1991, 1992 Linus Torvalds * Copyright 2007 rPath, Inc. - All Rights Reserved + * Copyright 2009 Intel Corporation; author H. Peter Anvin * * This file is part of the Linux kernel, and is made available under * the terms of the GNU General Public License version 2. @@ -16,24 +17,38 @@ #define SMAP 0x534d4150 /* ASCII "SMAP" */ +struct e820_ext_entry { + struct e820entry std; + u32 ext_flags; +} __attribute__((packed)); + static int detect_memory_e820(void) { int count = 0; u32 next = 0; - u32 size, id; + u32 size, id, edi; u8 err; struct e820entry *desc = boot_params.e820_map; + static struct e820_ext_entry buf; /* static so it is zeroed */ + + /* + * Set this here so that if the BIOS doesn't change this field + * but still doesn't change %ecx, we're still okay... + */ + buf.ext_flags = 1; do { - size = sizeof(struct e820entry); + size = sizeof buf; - /* Important: %edx is clobbered by some BIOSes, - so it must be either used for the error output - or explicitly marked clobbered. */ - asm("int $0x15; setc %0" + /* Important: %edx and %esi are clobbered by some BIOSes, + so they must be either used for the error output + or explicitly marked clobbered. Given that, assume there + is something out there clobbering %ebp and %edi, too. */ + asm("pushl %%ebp; int $0x15; popl %%ebp; setc %0" : "=d" (err), "+b" (next), "=a" (id), "+c" (size), - "=m" (*desc) - : "D" (desc), "d" (SMAP), "a" (0xe820)); + "=D" (edi), "+m" (buf) + : "D" (&buf), "d" (SMAP), "a" (0xe820) + : "esi"); /* BIOSes which terminate the chain with CF = 1 as opposed to %ebx = 0 don't always report the SMAP signature on @@ -51,8 +66,14 @@ static int detect_memory_e820(void) break; } + /* ACPI 3.0 added the extended flags support. If bit 0 + in the extended flags is zero, we're supposed to simply + ignore the entry -- a backwards incompatible change! */ + if (size > 20 && !(buf.ext_flags & 1)) + continue; + + *desc++ = buf.std; count++; - desc++; } while (next && count < ARRAY_SIZE(boot_params.e820_map)); return boot_params.e820_entries = count; |