On Sun, Dec 3, 2017 at 1:36 PM, Nicholas Piggin <npig...@gmail.com> wrote: > Seems like a reasonable approach. Why do we only do this for > powernv? It seems like a good idea in general to pull all > offlined CPUs out and into the same state for all platforms > and for all shutdown/restart/crash paths. >
The reason is largely wake-up related, do we expect offline CPUs to wake up in the kdump kernel. Largely the infrastructure allows us to selectively decide what platforms need this support. I did not want to break the world by enabling it across platforms (pseries for example) without good reason. > Also I wonder if there is anything we should do on the other > side of the equation for the kdump kernel to pull CPUs into a > known state rather than rely on the crash kernel to do it for > us. We might have a better ability to do that with system > reset IPIs now. > Yes, but do we need to do that or quickly dump the vmcore to a file and exit? Ideally we want the original kernel to wake offline cpus as appropriate (as we do with kexec) and send them to opal_reinit_cpus and make them spin on kexec_spin_wait(). The kdump kernel boots with maxcpus=1 and leaves them spinning > We still need to support platforms without NMI IPIs, so we > still need this patch as well. > True Thanks for the review! Balbir Singh
