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    SubjectRe: Opteron Rev E has a bug ... a locked instruction doesn't act as a read-acquire barrier
    Date
    On Monday 04 August 2008, Mikael Pettersson wrote:
    > Arkadiusz Miskiewicz writes:
    > > Hello,
    > >
    > > http://google-perftools.googlecode.com/svn-history/r48/trunk/src/base/at
    > >omicops-internals-x86.cc says
    > >
    > > " // Opteron Rev E has a bug in which on very rare occasions a locked
    > > // instruction doesn't act as a read-acquire barrier if followed by a
    > > // non-locked read-modify-write instruction. Rev F has this bug in
    > > // pre-release versions, but not in versions released to customers,
    > > // so we test only for Rev E, which is family 15, model 32..63
    > > inclusive. if (strcmp(vendor, "AuthenticAMD") == 0 && // AMD
    > > family == 15 &&
    > > 32 <= model && model <= 63) {
    > > AtomicOps_Internalx86CPUFeatures.has_amd_lock_mb_bug = true;
    > > } else {
    > > AtomicOps_Internalx86CPUFeatures.has_amd_lock_mb_bug = false;
    > > }
    > > "
    > >
    > > does kernel have quirk/workaround for this? I'm looking at
    > > arch/x86/kernel/cpu but I don't see workaround related to this (possibly
    > > I'm overlooking).
    >
    > I can find no reference to this alleged RevE erratum in the
    > Athlon64/Opteron revision guide (25759.pdf).
    >
    > But if this bug is real then we need to know about it. Could
    > you ask the author of the code you quoted above to clarify?

    Got answer, opensolaris has some workarounds for this bug I still don't know
    which errata # is that:

    http://groups.google.com/group/google-perftools/browse_thread/thread/3d1b78d4a9db8c6e

    btw. I got info about this bug after hiting this problem:
    http://bugs.mysql.com/bug.php?id=26081

    > /Mikael

    --
    Arkadiusz Miśkiewicz PLD/Linux Team
    arekm / maven.pl http://ftp.pld-linux.org/
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