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    SubjectRe: [PATCH 03/20] x86, mce: Add persistent MCE event
    On Wed, Nov 10, 2010 at 05:21:57PM -0500, Ingo Molnar wrote:
    >
    > * Ben Gamari <bgamari@gmail.com> wrote:
    >
    > > On Thu, 4 Nov 2010 16:36:39 +0100, Borislav Petkov <bp@amd64.org> wrote:
    > > > From: Borislav Petkov <borislav.petkov@amd.com>
    > > >
    > > > Add the necessary glue to enable the mce_record tracepoint on boot
    > > > turning it into a persistent event. This exports the MCE buffer
    > > > read-only to a userspace daemon which will hook into it through debugfs
    > > > when booting is finished.
    > >
    > > While MCE technically is a diagnostics service, do we want to start adding
    > > dependencies on debugfs in long-running, common-place daemons? I was under the
    > > impression we were to avoid using debugfs for anything other than values for
    > > one-off debugging.
    >
    > See this current discussion thread on lkml:
    >
    > [RFC][PATCH] perf: sysfs type id
    >
    > Events are being added to sysfs as we want to avoid the debugfs dependency.

    Yep, event enumeration will land in /sysfs eventually but in this case
    debugfs is used to export the buffers with the events recorded so far to
    the daemon which mmaps them. And I remember also being mentioned that
    debugfs will thus be always compiled in because of that.

    In any case, we need some kind of a facility with which to export those
    buffers for userspace to mmap. sysfs is clearly not that and debugfs is
    what we currently use. I'm open for better suggestions though.

    Thanks.

    --
    Regards/Gruss,
    Boris.

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