[PATCH 0/8] arm64 kexec kernel patches
mark.rutland at arm.com
Fri May 9 09:22:40 PDT 2014
On Fri, May 09, 2014 at 01:48:17AM +0100, Geoff Levand wrote:
> Hi Maintainers,
> This patchset adds support for kexec re-boots on arm64. I have tested with the
> VE fast model using various kernel config options with both spin and psci enable
> methods. I'll continue to test in the coming weeks.
> I tried to re-use the existing hot plug cpu_ops support for the secondary CPU
> shutdown as much as possible, but needed to do some things specific to kexec
> that I couldn't do with what was already there. A significant change is in
> [PATCH 4/8] (arm64: Add smp_spin_table_set_die) where I add the ability to setup
> a custom cpu_die handler.
> To get the the spin-table secondary CPUs into the proper state described in
> Documentation/arm64/booting.txt I use a three step spin loop. First in the
> kernel's virtual address space, then to the identity mapped address, then jump
> to the final spin code in the 2nd stage kernel's /memreserve/ area. To support
> this three step spin I needed [PATCH 5/8] (arm64: Split soft_restart into two
> stages). Please see the patch comments for more info. If we added the 2nd
> stage kernel's /memreserve/ area to the identity map we could eliminate the
> middle step and go from the VA space to the /memreserve/ area directly.
As I've covered in my reply to patch 7  I don't think this is a good
approach. I think a vastly better approach is to make kexec depend on
cpu hotplug support in SMP, and enable a simple hotplug-capable boot
protocol (e.g. extend spin-table with a cpu-return-addr).
That way the in-kernel portions of kexec can use the existing
infrastructure without tonnes of point hacks, and we enable a generic
hotplug capable mechanism for those systems which cannot implement PSCI.
> Please consider all patches for inclusion. Any comments or suggestions on how
> to improve would be very welcome.
> To load a kexec kernel and execute a kexec re-boot on arm64 my patches to
> kexec-tools, which have not yet been merged upstream, are needed:
Is the master branch up-to-date? The commit dates on all branches I can
see imply they haven't been updated in a while, and the code looks like
it needs some cleanup (there are some unused functions, hard-coded
More information about the kexec