Messages in this thread | | | Date | Thu, 12 Mar 2009 09:22:07 -0400 | From | Woody Suwalski <> | Subject | Re: [PATCH] ACPI: Check _PSS invalidation when BIOS report _PSS with all 0x80000000 |
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Len Brown wrote: > On Mon, 24 Nov 2008, Youquan,Song wrote: > > >> On Fri, Nov 21, 2008 at 03:08:39PM -0800, Andrew Morton wrote: >> >>> On Thu, 20 Nov 2008 19:08:36 -0800 (PST) >>> youquan_song@linux.intel.com wrote: >>> >>> >>>> Subject: Check _PSS invalidation when BIOS report _PSS with 0x80000000 >>>> >>>> When cpu frequencey scaling disable,some BIOS report _PSS with all >>>> 0x80000000. >>>> If kernel treat this case as valid, the kernel will boot crash when load >>>> cpufreq govenors. >>>> >>>> So in order to cover more buggy BIOSs, the patch just check _PSS core >>>> frequencey invalidtion. >>>> >>>> >>> It's unclear how many machines this will affect, and what the effects >>> of not having the patch are upon those machines. That is useful >>> information for people who are deciding whcih kernel versions this >>> patch should be merged into. >>> >> I meet 2 machines that if the P-states is disabled in BIOS, the kernel >> will boot crash at loading cpufreq_userspace governor because kernel >> consider that P-states validate. I know there are some other machines >> also exist this bug. >> > > What does _PPC say when P-states are disabled on these machines? > If it is disabling the _PSS, maybe we should not be looking at the _PSS? > > This would be a good patch if 0x80000000 were actually documented > in the ACPI spec as disabling P-states, but it isn't. > > Can you open a bugzilla and attach the acpidump output for > the two failing machines? Are those machines shipped with > P-states enabled by default, or disabled by default? > > Also, how, exactly, do we crash when we see these values? > > >>> Do you think this fix is needed in 2.6.28? 2.6.27.x? 2.6.26.x? etc? >>> >>> >> I know that the bug exists in kernel as old as 2.6.18 and also exits on >> 2.6.28, 2.6.27 etc. >> > > So we've been exposed to this BIOS bug for more than 10 releases > and the world has not ended. Unless we're about to be exposed to > a raft of new machines with this BIOS issue, and they have P-states > disabled by default, I'd say this workaround in not urgent. > > On Dell Latitude E4300 and E4600 I had to add processor.nocst=1 Otherwise system will become disfunctional after modprobing processor, typically on start of X or on exit from X... Do not have any of the systems on hand, but if useful can provide dmesg dump... I have not tried with 2.6.28 or earlier, so can not say if this is a regression or not.
Woody
-- Woody Suwalski, Xandros, Ottawa, Canada, 1-613-842-3498 x414
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