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-   -   x86: work around X86-32 kernel failures on Intel Atom CPU (http://www.linux-archive.org/ubuntu-kernel-team/327507-x86-work-around-x86-32-kernel-failures-intel-atom-cpu.html)

Amit Kucheria 02-17-2010 01:09 PM

x86: work around X86-32 kernel failures on Intel Atom CPU
 
On 10 Feb 17, Colin King wrote:
> From: Colin Ian King <colin.king@canonical.com>
>
> *** HARDY LPIA ONLY ***
>
> BugLink: https://bugs.launchpad.net/bugs/523112
>
> This is a workaround to errata AAE44 as listed in
> http://download.intel.com/design/processor/specupdt/319536.pdf,
> page 33, namely: "Code Fetch May Occur to Incorrect Address
> After a Large Page is Split into 4-KB Byte Pages". This is the same
> as Errata AAH41 (Atom 3xx series) but named AAE44 for the Atom
> Z5xx series.
>
> This fix is not totally bullet proof. There is still a possibility
> of a race between __set_pmd_pte and __flush_tlb_all() during which
> the other hyperthread could do a code fetch and get garbage. Hence
> this patch narrows the window for the race but does not completely
> prevent it.
>
> This patch has been soak tested on an Atom Z530 for 2 hours. Without
> this patch, the soak test can reproduce an oops within 5 minutes of
> testing.
>
> Also boot tested on two Atom N270 netbooks and Intel
>
>
> This patch is a backport of the upstream commit
> 211b3d03c7400f48a781977a50104c9d12f4e229, the original commit message
> was as follows:
>
> Impact: work around boot crash
>
> Work around Intel Atom erratum AAH41 (probabilistically) - it's triggering
> in the field.
>
> Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
> Tested-by: Kyle McMartin <kyle@redhat.com>
> Signed-off-by: Ingo Molnar <mingo@elte.hu>
> Signed-off-by: Colin Ian King <colin.king@canonical.com>
>
>
> Colin Ian King (1):
> UBUNTU: x86: work around X86-32 kernel failures on Intel Atom CPU
>
> arch/x86/mm/pageattr_32.c | 11 +++++++++++
> 1 files changed, 11 insertions(+), 0 deletions(-)
>
> --

Acked-by: Amit Kucheria <amit.kucheria@canonical.com>

--
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Amit Kucheria, Kernel Engineer || amit.kucheria@canonical.com
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