On Fri, Aug 24, 2012 at 03:34:34PM +0200, Stephane Eranian wrote: > > The following patch, relative to 3.6.0-rc3, makes > the microcode update code path actually invoke the > perf_check_microcode() function and thus potentially > renabling SNB PEBS. > > By default, CONFIG_MICROCODE_OLD_INTERFACE is > forced to Y in arch/x86/Kconfig. There is no > way to disable this. That means that the code > path used in arch/x86/kernel/microcode_core.c > did not include the call to perf_check_microcode(). > > Thus, even though the microcode was updated to a > version that fixes the SNB PEBS problem, perf_event > would still return EOPNOTSUPP when enabling precise > sampling. > > This patch simply adds a call to perf_check_microcode() > in the call path used when OLD_INTERFACE=y.
Ok, so c93dc84cbe324 added calls to perf_check_microcode but it looks like you're updating the microcode from /dev/cpu/microcode, correct? And if so, the old interface got missed. Oh well, as long as we have to support it, we might as well add that perf call there - it will go when the interface goes anyway so until then: Acked-by: Borislav Petkov <[email protected]> > > Signed-off-by: Stephane Eranian <[email protected]> > --- > > --- a/arch/x86/kernel/microcode_core.c > +++ b/arch/x86/kernel/microcode_core.c > @@ -225,6 +225,9 @@ static ssize_t microcode_write(struct file *file, const > char __user *buf, > if (do_microcode_update(buf, len) == 0) > ret = (ssize_t)len; > > + if (ret > 0) > + perf_check_microcode(); > + > mutex_unlock(µcode_mutex); > put_online_cpus(); > > Thanks. -- Regards/Gruss, Boris. Advanced Micro Devices GmbH Einsteinring 24, 85609 Dornach GM: Alberto Bozzo Reg: Dornach, Landkreis Muenchen HRB Nr. 43632 WEEE Registernr: 129 19551 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
