• Ingo Molnar's avatar
    perf, x86: Complain louder about BIOSen corrupting CPU/PMU state and continue · 45daae57
    Ingo Molnar authored
    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:
    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: default avatarEric Dumazet <eric.dumazet@gmail.com>
    Suggested-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    Acked-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
    Cc: Frederic Weisbecker <fweisbec@gmail.com>
    Cc: Mike Galbraith <efault@gmx.de>
    Cc: Steven Rostedt <rostedt@goodmis.org>
    LKML-Reference: <new-submission>
    Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
perf_event.c 42.5 KB