> -----Original Message----- > From: Michael Ellerman [mailto:m...@ellerman.id.au] > Sent: Tuesday, December 23, 2014 9:01 AM > To: Wang Dongsheng-B40534 > Cc: b...@kernel.crashing.org; Wood Scott-B07421; an...@samba.org; linuxppc- > d...@lists.ozlabs.org > Subject: Re: [PATCH] powerpc/smp: Fix Non-boot cpus cannot be bring up. > > On Mon, 2014-12-22 at 14:38 +0800, Dongsheng Wang wrote: > > From: Wang Dongsheng <dongsheng.w...@freescale.com> > > > > Kernel cannot bring up Non-boot cpus always get "Processor xx is stuck". > > this issue bring by http://patchwork.ozlabs.org/patch/418912/ (powerpc: > > Secondary CPUs must set cpu_callin_map after setting active and > > online) We need to take timebase after bootup cpu give the timebase firstly. > > > > When start_secondary, non-boot cpus set cpu_callin_map for boot cpu > > after that boot cpu will give the timebase for non-boot cpu. Otherwise > > non-boot cpus will fall in dead loop to waiting bootup cpu to give > > imebase. > > Right. > > However, doesn't this introduce the possibility that the secondary cpu is up > and > marked online but has an unsynchronised clock? > Yes, right. But Freescale platform boot-cpu will freeze the TB until secondary cpu take the time base, so the clock is synchronized.
For generic PowerPC maybe has this issue. So for safe I think we need to set cpu online after synchronized clock. I will update my patch if you agree this way. + if (smp_ops->take_timebase) + smp_ops->take_timebase(); + secondary_cpu_time_init(); + Move set_cpu_online to here. + set_cpu_online(cpu, true); Regards, -Dongsheng _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
