ARM kexec SMP problem using exynos4210

[Will Deacon]

On Wed, Jan 11, 2012 at 05:20:43PM +0000, McClintock Matthew-B29882 wrote:
> On Wed, Jan 11, 2012 at 5:03 AM, Will Deacon <will.deacon at arm.com> wrote:
> > On Wed, Jan 11, 2012 at 10:23:18AM +0000, Joonyoung Shim wrote:
> >> One more question, generally boot cpu is first cpu(cpu0). If current
> >> cpu is secondary cpu(cpu1), smp_send_stop of machine_shutdown will stop
> >> first cpu and next kernel will try to boot on secondary cpu. Is it
> >> possible?
> >
> > I added the cpu_logical_map stuff for this, so the kernel can handle it.
> > That said, your platform may have restrictions about the boot CPU so if it
> > doesn't work, you'll need to taskset the kexec command to CPU 0.
> 
> Would this negatively effect kdump though where you might not be able
> to switch back to cpu0? I think It's best to be able to boot on any
> core.

Ideally, we would boot on any core. That's what the logical map is for. The
problem is that you may have hardware restrictions that prevent this (for
example, the secure monitor on OMAP4 is, I believe, only present on CPU 0).

Will