Revision 9855d8ce41a7801548a05d844db2f46c3e810166 authored by Stefan Bader on 22 January 2013, 12:37:21 UTC, committed by Rafael J. Wysocki on 22 January 2013, 12:37:21 UTC
To fix incorrect P-state frequencies which can happen on some AMD systems f594065faf4f9067c2283a34619fc0714e79a98d "ACPI: Add fixups for AMD P-state figures" introduced a quirk to obtain the correct values by reading from AMD specific MSRs. This did cause a regression when running a kernel using that quirk under Xen which does (currently) not pass through MSR reads to the HW. Instead the guest gets a 0 in return. And this seems to cause a failure to initialize the ondemand governour (hard to say for sure as all P-states appear to run at the same frequency). While this should also be fixed in the hypervisor (to allow a guest to read that MSR), this patch is intended to work around the issue in the meantime. In discussion it turned out that indeed real HW/BIOSes may choose to not set the valid bit and thus mark the P-state as invalid. So this could be considered a fix for broken BIOSes that also works around the issue on Xen. Signed-off-by: Stefan Bader <stefan.bader@canonical.com> Cc: 3.7+ <stable@vger.kernel.org> Acked-by: Borislav Petkov <bp@suse.de> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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File | Mode | Size |
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Makefile | -rw-r--r-- | 164 bytes |
file-mmu.c | -rw-r--r-- | 1.5 KB |
file-nommu.c | -rw-r--r-- | 6.6 KB |
inode.c | -rw-r--r-- | 6.7 KB |
internal.h | -rw-r--r-- | 536 bytes |
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