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perf, x86: Complain louder about BIOSen corrupting CPU/PMU state and …
…continue Eric Dumazet reported that hardware PMU events do not work on his system, due to the BIOS corrupting PMU state: Performance Events: PEBS fmt0+, Core2 events, Broken BIOS detected, using software events only. [Firmware Bug]: the BIOS has corrupted hw-PMU resources (MSR 186 is 43003c) Linus suggested that we continue in the face of such BIOS-induced CPU state corruption: http://lkml.org/lkml/2011/3/24/608 Such BIOSes will have to be fixed - Linux developers rely on a working and fully capable PMU and the BIOS interfering with the CPU's PMU state is simply not acceptable. So this patch changes perf to continue when it detects such BIOS interaction, some hardware events may be unreliable due to the BIOS writing and re-writing them - there's not much the kernel can do about that but to detect the corruption and report it. Reported-and-tested-by: Eric Dumazet <[email protected]> Suggested-by: Linus Torvalds <[email protected]> Acked-by: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Arnaldo Carvalho de Melo <[email protected]> Cc: Frederic Weisbecker <[email protected]> Cc: Mike Galbraith <[email protected]> Cc: Steven Rostedt <[email protected]> LKML-Reference: <new-submission> Signed-off-by: Ingo Molnar <[email protected]>
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