diff options
Diffstat (limited to 'arch/i386/boot/memory.c')
| -rw-r--r-- | arch/i386/boot/memory.c | 39 |
1 files changed, 29 insertions, 10 deletions
diff --git a/arch/i386/boot/memory.c b/arch/i386/boot/memory.c index 1a2e62db8be..378353956b5 100644 --- a/arch/i386/boot/memory.c +++ b/arch/i386/boot/memory.c @@ -20,6 +20,7 @@ static int detect_memory_e820(void) { + int count = 0; u32 next = 0; u32 size, id; u8 err; @@ -27,20 +28,33 @@ static int detect_memory_e820(void) do { size = sizeof(struct e820entry); - id = SMAP; + + /* 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" - : "=am" (err), "+b" (next), "+d" (id), "+c" (size), + : "=d" (err), "+b" (next), "=a" (id), "+c" (size), "=m" (*desc) - : "D" (desc), "a" (0xe820)); + : "D" (desc), "d" (SMAP), "a" (0xe820)); + + /* Some BIOSes stop returning SMAP in the middle of + the search loop. We don't know exactly how the BIOS + screwed up the map at that point, we might have a + partial map, the full map, or complete garbage, so + just return failure. */ + if (id != SMAP) { + count = 0; + break; + } - if (err || id != SMAP) + if (err) break; - boot_params.e820_entries++; + count++; desc++; - } while (next && boot_params.e820_entries < E820MAX); + } while (next && count < E820MAX); - return boot_params.e820_entries; + return boot_params.e820_entries = count; } static int detect_memory_e801(void) @@ -89,11 +103,16 @@ static int detect_memory_88(void) int detect_memory(void) { + int err = -1; + if (detect_memory_e820() > 0) - return 0; + err = 0; if (!detect_memory_e801()) - return 0; + err = 0; + + if (!detect_memory_88()) + err = 0; - return detect_memory_88(); + return err; } |