diff options
Diffstat (limited to 'arch/x86/boot/memory.c')
| -rw-r--r-- | arch/x86/boot/memory.c | 29 |
1 files changed, 13 insertions, 16 deletions
diff --git a/arch/x86/boot/memory.c b/arch/x86/boot/memory.c index d989de810ca..cae3feb1035 100644 --- a/arch/x86/boot/memory.c +++ b/arch/x86/boot/memory.c @@ -17,17 +17,12 @@ #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; struct biosregs ireg, oreg; struct e820entry *desc = boot_params.e820_map; - static struct e820_ext_entry buf; /* static so it is zeroed */ + static struct e820entry buf; /* static so it is zeroed */ initregs(&ireg); ireg.ax = 0xe820; @@ -36,10 +31,18 @@ static int detect_memory_e820(void) ireg.di = (size_t)&buf; /* - * Set this here so that if the BIOS doesn't change this field - * but still doesn't change %ecx, we're still okay... + * Note: at least one BIOS is known which assumes that the + * buffer pointed to by one e820 call is the same one as + * the previous call, and only changes modified fields. Therefore, + * we use a temporary buffer and copy the results entry by entry. + * + * This routine deliberately does not try to account for + * ACPI 3+ extended attributes. This is because there are + * BIOSes in the field which report zero for the valid bit for + * all ranges, and we don't currently make any use of the + * other attribute bits. Revisit this if we see the extended + * attribute bits deployed in a meaningful way in the future. */ - buf.ext_flags = 1; do { intcall(0x15, &ireg, &oreg); @@ -61,13 +64,7 @@ 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 (oreg.cx > 20 && !(buf.ext_flags & 1)) - continue; - - *desc++ = buf.std; + *desc++ = buf; count++; } while (ireg.ebx && count < ARRAY_SIZE(boot_params.e820_map)); |