Possible regression in kexec on ARM ARMv6 and ARMv7 cores

Simon Horman horms at verge.net.au
Fri Oct 21 04:59:58 EDT 2011

On Fri, Oct 21, 2011 at 09:46:41AM +0100, Will Deacon wrote:
> On Fri, Oct 21, 2011 at 09:34:26AM +0100, Simon Horman wrote:
> > I have tested the kexec/mmu-off branch of your tree on the UP board
> > I mentioned above and kexec works :)
> Hurrah! Thanks for giving it a spin.
> > > You mention UP in particular, which I will test.
> > > Do you have any thoughts on SMP?
> Yes. Currently [i.e. on my branch above] you can do SMP kexec using the CPU
> hotplug platform_cpu_kill callback to take down the CPUs in some
> platform-specific manner.

Thanks, I will take a look into it.

> The more difficult case is when you want to offline the secondary CPUs into
> a pen and then boot them in the new kernel. I did get some of this working,
> but there are outstanding issues with whether the pen should be at a fixed
> location or not. If not, then we need a way to tell the new kernel where it
> is, which may involve updating the DT blob...

Is the implication that the (working) callback method does not
give the second kernel any secondary CPUs?

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