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@xxxxxxxxxxxxxxx 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. -- Len Brown, Intel Open Source Technology Center -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
