On 26/09/07 14:20 -0700, H. Peter Anvin wrote:
> Testing this patch now:
>
> >From 2efa33f81ef56e7700c09a3d8a881c96692149e5 Mon Sep 17 00:00:00 2001
> From: H. Peter Anvin <[email protected]>
> Date: Wed, 26 Sep 2007 14:11:43 -0700
> Subject: [PATCH] [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 <[email protected]>
> Cc: Jordan Crouse <[email protected]>
> Cc: Joerg Pommnitz <[email protected]>
> ---
> arch/i386/boot/memory.c | 30 +++++++++++++++++++++++-------
> 1 files changed, 23 insertions(+), 7 deletions(-)
>
> diff --git a/arch/i386/boot/memory.c b/arch/i386/boot/memory.c
> index 1a2e62d..bccaa1c 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;
> @@ -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;
> + }
>
> - boot_params.e820_entries++;
> + if (err)
> + break;
> +
> + 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;
> +
> + if (!detect_memory_88())
> + err = 0;
>
> - return detect_memory_88();
> + return err;
> }
> --
> 1.5.3.1
>
Works here with the buggy BIOS.
Acked-by: Jordan Crouse <[email protected]>
Thanks.
--
Jordan Crouse
Systems Software Development Engineer
Advanced Micro Devices, Inc.
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