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[x86 setup] Handle case of improperly terminated E820 chain 

At least one system (a Geode system with a Digital Logic BIOS) has
been found which suddenly stops reporting the SMAP signature when
reading the E820 memory chain.  We can't know what, exactly, broke in
the BIOS, so if we detect this situation, declare the E820 data
unusable and fall back to E801.

Also, revert to original behavior of always probing all memory
methods; that way all the memory information is available to the
kernel.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Cc: Jordan Crouse <jordan.crouse@amd.com>
Cc: Joerg Pommnitz <pommnitz@yahoo.com>
This commit is contained in:
H. Peter Anvin 2007-09-26 14:11:43 -07:00
parent bbc15f46fe
commit 2efa33f81e
1 changed files with 23 additions and 7 deletions
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30
arch/i386/boot/memory.c
View File

@ -20,6 +20,7 @@
static int detect_memory_e820(void)
{
int count = 0;
u32 next = 0;
u32 size, id;
u8 err;
@ -33,14 +34,24 @@ static int detect_memory_e820(void)
"=m" (*desc)
: "D" (desc), "a" (0xe820));
if (err || id != SMAP)
/* 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)
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 +100,16 @@ 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;
return detect_memory_88();
if (!detect_memory_88())
err = 0;
return err;
}