On Tue, Jun 25, 2013 at 04:52:39PM +0530, Anshuman Khandual wrote: > On 06/24/2013 04:58 PM, Michael Ellerman wrote: > > In pmu_disable() we disable the PMU by setting the FC (Freeze Counters) > > bit in MMCR0. In order to do this we have to read/modify/write MMCR0. > > > > It's possible that we read a value from MMCR0 which has PMAO (PMU Alert > > Occurred) set. When we write that value back it will cause an interrupt > > to occur. We will then end up in the PMU interrupt handler even though > > we are supposed to have just disabled the PMU. > > > > Is that possible ? First of all MMCR0[PMAO] could not be written by SW. > Even if you try writing it, how its going to generate PMU interrupt ? > HW sets this bit MMCR0[PMAO] after a PMU interrupt has already occurred > not that if we set this, a PMU interrupt would be generated.
Yes it's possible. cheers _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
