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    SubjectRe: [PATCH] perf, ibs: Check syscall attribute flags
    On 07.09.12 11:11:56, David Ahern wrote:
    > On 9/7/12 11:07 AM, Robert Richter wrote:
    > >> Am I reading this right - if exclude_guest is set then perf_ibs_init
    > >> returns -EINVAL?
    > >
    > > Yes, the hardware does not support this. I will look for a solution
    > > which emulates this is software.
    >
    > ugh, that's exactly we need for Intel: if precise is set, exclude_guest
    > must be set.
    >
    > In perf I would like to set exclude_guest if precise is set -- what I
    > mentioned yesterday for the patch https://lkml.org/lkml/2012/7/20/437.
    > With my patch -e cycles:p on AMD will then fail EINVAL.

    You may set this bit per default. On EINVAL perf falls back and clears
    the bit. I tested exactly this for ibs and it works.

    So, on Intel, if the guest_exclude bit is not set, the kernel simply
    throws an EINVAL too, but since perf sets it per default with the
    precise modifier there shouldn't be any problem here.

    -Robert

    --
    Advanced Micro Devices, Inc.
    Operating System Research Center



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