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SubjectRe: [Qemu-devel] [RFH] qemu-2.6 memory corruption with OVMF and linux-4.9
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Hello,

Am 17.06.2017 um 18:51 schrieb Laszlo Ersek:
> (I also recommend using the "vbindiff" tool for such problems, it is
> great for picking out patterns.)
>
> ** ** ** ** ** ** ** ** 8 9 ** ** ** 13 14 15
> -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
> 00000000 01 e8 00 00 00 00 00 00 8c 5e 00 00 00 10 ff f1
> 00000010 5b 78 8a 3e 00 00 00 00 00 00 00 00 00 00 00 00
> 00000020 8c 77 00 00 00 12 00 02 18 f0 00 00 00 00 00 00
> 00000030 00 1e 00 00 00 00 00 00 8c 8c 00 00 00 12 00 02
> 00000040 07 70 00 00 00 00 00 00 00 14 00 00 00 00 00 00
> 00000050 8c 9c 00 00 00 12 00 02 22 00 00 00 00 00 00 00
> 00000060 00 40 00 00 00 00 00 00 8c ac 00 00 00 10 ff f1
>
> 00000000 01 e8 00 00 00 00 00 00 00 3c 00 00 00 17 00 00
> 00000010 5b 78 8a 3e 00 00 00 00 00 3c 00 00 00 07 00 00
> 00000020 8c 77 00 00 00 12 00 02 00 3c 00 00 00 07 00 00
> 00000030 00 1e 00 00 00 00 00 00 00 3c 00 00 00 17 00 00
> 00000040 07 70 00 00 00 00 00 00 00 3c 00 00 00 07 00 00
> 00000050 8c 9c 00 00 00 12 00 02 00 3c 00 00 00 07 00 00
> 00000060 00 40 00 00 00 00 00 00 00 3c 00 00 00 17 00 00
> -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
> ** ** ** ** ** ** ** ** 8 9 ** ** ** 13 14 15
>
> The columns that I marked with "**" are identical between "good" and
> "bad". (These are columns 0-7, 10-12.)
>
> Column 8 is overwritten by zeros (every 16th byte).
>
> Column 9 is overwritten by 0x3c (every 16th byte).
>
> Column 13 is super interesting. The most significant nibble in that
> column is not disturbed. And, in the least significant nibble, the least
> significant three bits are turned on. Basically, the corruption could be
> described, for this column (i.e., every 16th byte), as
>
> bad = good | 0x7
>
> Column 14 is overwritten by zeros (every 16th byte).
>
> Column 15 is overwritten by zeros (every 16th byte).
>
> My take is that your host machine has faulty RAM. Please run memtest86+
> or something similar.

I will do so, but for me very unlikely:
- it never happens with BIOS, only with OVMF
- for each test I start q new QEMU process, which should use a different
memory region
- it repeatedly hits e1000 or libata.ko

After updating from OVMF to 0~20161202.7bbe0b3e-1 from
(0~20160813.de74668f-2 it has not yet happened again.

Anyway, thank you for your help.

Philipp

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