On Sat, Aug 4, 2018 at 10:48 AM Michael Ellerman <m...@ellerman.id.au> wrote: > > Hi Pingfan, > > Pingfan Liu <kernelf...@gmail.com> writes: > > Technically speaking, echo 1/0 > cpuX/online is only a subset of cpu > > hotplug/unplug, i.e. add/remove. The latter one includes the physical > > adding/removing of a cpu device. Some user space tools such as kexec-tools > > resort to the event add/remove to automatically rebuild dtb. > > If the dtb is not rebuilt correctly, we may hang on 2nd kernel due to > > lack the info of boot-cpu-hwid in dtb. > > I notice you also sent a patch for ppc64_cpu to deal with CPUs being > removed rather than just offlined. > > If I apply this patch then existing ppc64_cpu (without your other patch) > will break. Is that right? > Yes. Since removing cpu will make a hole in cpu map, but ppc64_cpu code takes the assumption that the cpu map is contiguous.
Thanks, Pingfan
