From 19ab428f4b7988ef3ac727c680efc193ef53ce14 Mon Sep 17 00:00:00 2001 From: Stephen Warren Date: Fri, 14 Jun 2013 16:14:14 +0100 Subject: ARM: 7759/1: decouple CPU offlining from reboot/shutdown Add comments to machine_shutdown()/halt()/power_off()/restart() that describe their purpose and/or requirements re: CPUs being active/not. In machine_shutdown(), replace the call to smp_send_stop() with a call to disable_nonboot_cpus(). This completely disables all but one CPU, thus satisfying the requirement that only a single CPU be active for kexec. Adjust Kconfig dependencies for this change. In machine_halt()/power_off()/restart(), call smp_send_stop() directly, rather than via machine_shutdown(); these functions don't need to completely de-activate all CPUs using hotplug, but rather just quiesce them. Remove smp_kill_cpus(), and its call from smp_send_stop(). smp_kill_cpus() was indirectly calling smp_ops.cpu_kill() without calling smp_ops.cpu_die() on the target CPUs first. At least some implementations of smp_ops had issues with this; it caused cpu_kill() to hang on Tegra, for example. Since smp_send_stop() is only used for shutdown, halt, and power-off, there is no need to attempt any kind of CPU hotplug here. Adjust Kconfig to reflect that machine_shutdown() (and hence kexec) relies upon disable_nonboot_cpus(). However, this alone doesn't guarantee that hotplug will work, or even that hotplug is implemented for a particular piece of HW that a multi-platform zImage runs on. Hence, add error-checking to machine_kexec() to determine whether it did work. Suggested-by: Russell King Signed-off-by: Stephen Warren Acked-by: Will Deacon Tested-by: Zhangfei Gao Signed-off-by: Russell King --- arch/arm/Kconfig | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch/arm/Kconfig') diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index 239fa96c12bb..2651b1da1c56 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -2016,7 +2016,7 @@ config XIP_PHYS_ADDR config KEXEC bool "Kexec system call (EXPERIMENTAL)" - depends on (!SMP || HOTPLUG_CPU) + depends on (!SMP || PM_SLEEP_SMP) help kexec is a system call that implements the ability to shutdown your current kernel, and to start another kernel. It is like a reboot -- cgit v1.2.3