On 08/04/2019 14:53, Julien Grall wrote: > Hi Andrew, > > On 4/8/19 1:09 PM, Andrew Cooper wrote: >> On 08/04/2019 12:38, Julien Grall wrote: >>> Hi, >>> >>> On 4/8/19 11:47 AM, Andrew Cooper wrote: >>>> On 08/04/2019 11:39, Julien Grall wrote: >>>>> Hi, >>>>> >>>>> On 4/8/19 10:39 AM, Andrew Cooper wrote: >>>>>> + case CPU_RESUME_FAILED: >>>>>> + if ( !park_offline_cpus && system_state != >>>>>> SYS_STATE_suspend ) >>>>> >>>>> This patch breaks compilation on arm32/arm64 because >>>>> park_offline_cpus >>>>> is not defined: >>>>> >>>>> timer.c: In function 'cpu_callback': >>>>> timer.c:651:15: error: 'park_offline_cpus' undeclared (first use in >>>>> this function) >>>>> if ( !park_offline_cpus && system_state != >>>>> SYS_STATE_suspend ) >>>>> ^~~~~~~~~~~~~~~~~ >>>>> >>>>> What is the purpose of park_offline_cpus? >>>> >>>> Sorry. I should have waited for a full build test first. >>>> >>>> park_offline_cpus is a workaround for Intel's MCE behaviour, where the >>>> system will shut down rather than deliver an #MC if machine checking >>>> isn't configured on all CPUs. >>>> >>>> As a result, we have to start all CPUs, even beyond maxcpus= and >>>> set up >>>> machine check handling, and never ever free their stacks, even if we'd >>>> prefer the CPUs to be offline. >>> >>> I am a bit confused, why this is necessary now for the timer and not >>> in other places of the common code? >>> >>>> >>>> Are you happy with a >>>> >>>> #define park_offline_cpus false > >>>> in ARM? >>> >>> The name is fairly confusing if you don't know the background. >>> >>> But I have to admit that even with your explanation above, I still >>> don't understand why you need to check park_offline_cpus in the timers. >> >> It is all to do with how/when we free per-cpu data. >> >> Technically speaking (with the memory leak fixed) the old arrangement >> ought to function correctly, but the new arrangement is more efficient. > Where would the free happen in the "less efficient" way?
I don't quite understand the question. https://lists.xenproject.org/archives/html/xen-devel/2019-03/msg02252.html is the v1 patch, but that has already been rejected for not using the up-to-date notifier layout. ~Andrew _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
