Hi Stephen, On Wed, Dec 19, 2012 at 11:44:41PM +0000, Stephen Warren wrote: > From: Stephen Warren <swarren at nvidia.com> > > Both the regular reboot and shutdown paths do this. It seems reasonable > for kexec to work the same way. > > On the Tegra ARM SoC at least, this change allows kexec to work with SMP > enabled. ARM's machine_shutdown() simply puts all CPUs into a loop. If > the code of that loop is over-written, the CPUs may crash, and cause the > kexec'd kernel not to be able to initialize them. In practice, this > causes the kexec'd kernel to hang and/or crash. The intended way to > solve this is for ARM machines to provide a cpu_kill SMP operation to > e.g. power down the CPUs, or place them in reset. However, at least on > Tegra, the implementation of that function would simply be duplicating > the hotplug code that already exists, so it seems simpler to just call > disable_nonboot_cpus() for the kexec path, just like reboot/shutdown. If you do manage to get this merged, please can you follow up with a patch to remove the smp_kill_cpus bits from arch/arm/kernel/smp.c please? It only exists as a hook to do exactly this and currently nobody is using it afaict. Cheers, Will
