From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dave.Martin@arm.com (Dave Martin) Date: Tue, 1 Oct 2013 19:12:11 +0100 Subject: [PATCH v3 2/3] ARM: mcpm: Implement cpu_kill() to synchronise on powerdown In-Reply-To: References: <1380647718-9178-1-git-send-email-Dave.Martin@arm.com> <1380647718-9178-3-git-send-email-Dave.Martin@arm.com> Message-ID: <20131001181211.GC2640@localhost.localdomain> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Tue, Oct 01, 2013 at 01:35:17PM -0400, Nicolas Pitre wrote: > On Tue, 1 Oct 2013, Dave Martin wrote: > > > CPU hotplug and kexec rely on smp_ops.cpu_kill(), which is supposed > > to wait for the CPU to park or power down, and perform the last > > rites (such as disabling clocks etc., where the platform doesn't do > > this automatically). > > > > kexec in particular is unsafe without performing this > > synchronisation to park secondaries. Without it, the secondaries > > might not be parked when kexec trashes the kernel. > > > > There is no generic way to do this synchronisation, so a new mcpm > > platform_ops method power_down_finish() is added by this patch. > > > > The new method is mandatory. A platform which provides no way to > > detect when CPUs are parked is likely broken. > > > > Signed-off-by: Dave Martin > > Reviewed-by: Nicolas Pitre Thanks! I can recommend kexec -- speeds up my reboots no end. I can send the MCPM patches to the patch system, but the TC2 patch probably ought to go via arm-soc when Russell has a stable branch available. Lorenzo's patch fixes something relevant but independent, so should be mergeable separately. Any concerns? Cheers ---Dave