This is a note to let you know that I've just added the patch titled
x86, amd: Do not enable ARAT feature on AMD processors below
to the 2.6.33-longterm tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/longterm/longterm-queue-2.6.33.git;a=summary
The filename of the patch is:
x86-amd-do-not-enable-arat-feature-on-amd-processors-below.patch
and it can be found in the queue-2.6.33 subdirectory.
If you, or anyone else, feels it should not be added to the 2.6.33 longterm
tree,
please let <[email protected]> know about it.
>From e9cdd343a5e42c43bcda01e609fa23089e026470 Mon Sep 17 00:00:00 2001
From: Boris Ostrovsky <[email protected]>
Date: Thu, 26 May 2011 11:19:52 -0400
Subject: x86, amd: Do not enable ARAT feature on AMD processors below
family 0x12
From: Boris Ostrovsky <[email protected]>
commit e9cdd343a5e42c43bcda01e609fa23089e026470 upstream.
Commit b87cf80af3ba4b4c008b4face3c68d604e1715c6 added support for
ARAT (Always Running APIC timer) on AMD processors that are not
affected by erratum 400. This erratum is present on certain processor
families and prevents APIC timer from waking up the CPU when it
is in a deep C state, including C1E state.
Determining whether a processor is affected by this erratum may
have some corner cases and handling these cases is somewhat
complicated. In the interest of simplicity we won't claim ARAT
support on processor families below 0x12 and will go back to
broadcasting timer when going idle.
Signed-off-by: Boris Ostrovsky <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Tested-by: Boris Petkov <[email protected]>
Cc: Hans Rosenfeld <[email protected]>
Cc: Andreas Herrmann <[email protected]>
Cc: Chuck Ebbert <[email protected]>
Signed-off-by: H. Peter Anvin <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
arch/x86/kernel/cpu/amd.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -565,8 +565,11 @@ static void __cpuinit init_amd(struct cp
}
#endif
- /* As a rule processors have APIC timer running in deep C states */
- if (c->x86 > 0xf && !cpu_has_amd_erratum(amd_erratum_400))
+ /*
+ * Family 0x12 and above processors have APIC timer
+ * running in deep C states.
+ */
+ if (c->x86 > 0x11)
set_cpu_cap(c, X86_FEATURE_ARAT);
/*
Patches currently in longterm-queue-2.6.33 which might be from [email protected]
are
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