[RESEND PATCH] ARM: kexec: Fix validating CPU hotplug support
Russell King - ARM Linux
linux at arm.linux.org.uk
Tue Nov 4 02:55:25 PST 2014
On Tue, Nov 04, 2014 at 05:40:25PM +0800, HuKeping wrote:
> Commit 2103f6cba61a8b8bea3fc1b63661d830a2125e76 added a hotplug checking in
> machine_kexec_prepare(), but it will lead a failure when loading the
> crash-kernel in some cases.
> Kexec utility can load the crash kernel by two ways:
> 1. kexec -l kernel-image
> 2. kexec -p kernel-image
> In case #1, for rapid reboot, it's correct to do the hotplug checking things,
> for it will shut down cpus in _cpu_down() later when command "kexec -e" be
> sent, this routine needs the support of cpu hotplug.
> In case #2, for use on panic, it's unnecessary to do the same thing, the whole
> routing has no business with cpu shutting down. Check for cpu hot plug will
> lead a failure to load the kernel.
So what happens to the other CPUs when you kexec into the new kernel,
possibly overwriting the instructions which those CPUs are executing?
FTTC broadband for 0.8mile line: currently at 9.5Mbps down 400kbps up
according to speedtest.net.
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