On 07/30/2013 04:05 AM, Vijay Kilari wrote: > On Fri, Jul 26, 2013 at 10:35 PM, Stephen Warren <swarren at wwwdotorg.org> wrote: >> On 07/25/2013 11:41 PM, vijay.kilari at gmail.com wrote: >>> From: Vijaya Kumar K <Vijaya.Kumar at caviumnetworks.com> >>> >>> In case of normal kexec kernel load, all cpu's are offlined >>> before calling machine_kexec() under kernel_kexec() function. >> >> I'm not sure that's true, unless perhaps you have CONFIG_KEXEC_JUMP enabled? >> >>> But in case crash panic cpus are relaxed in >>> machine_crash_nonpanic_core() SMP function but not offlined. >>> >>> When crash kernel is loaded with kexec and on panic trigger >>> machine_kexec() checks for number of cpus online. >>> If more than one cpu is online machine_kexec() fails to load >>> with below error >>> >>> kexec: error: multiple CPUs still online >>> >>> In machine_crash_nonpanic_core() SMP function, offline CPU >>> before cpu_relax >> >>> diff --git a/arch/arm/kernel/machine_kexec.c b/arch/arm/kernel/machine_kexec.c >> >>> @@ -73,6 +73,7 @@ void machine_crash_nonpanic_core(void *unused) >>> crash_save_cpu(®s, smp_processor_id()); >>> flush_cache_all(); >>> >>> + set_cpu_online(smp_processor_id(), false); >> >> I'm not familiar with that API, but it looks like it's just setting the >> *current* CPU offline. That sounds problematic for two reasons: >> >> 1) Setting the current CPU offline sounds like a bad idea; after all, >> code is still running on it. Presumably you want to offline all other CPUs. >> > machine_crash_nonpanic_core() is a SMP call (smp_call_function) . > Setting cpu offline is called for all other CPUs except the caller. Ah OK, that's what I was missing. This makes sense then.
