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* [PATCH 0/1 RESEND 2] ARM: plat-versatile: move secondary CPU startup out of .init.
@ 2012-11-27  8:39 ` Claudio Fontana
  0 siblings, 0 replies; 10+ messages in thread
From: Claudio Fontana @ 2012-11-27  8:39 UTC (permalink / raw)
  To: linux-arm-kernel


Hello,

I am implementing virtual CPU hotplug for the the ARM Cortex A-15 VExpress motherboard.
This is mainly a QEMU feature, which allows dynamically changing the number
of CPUs in the guest.

I stumbled upon a limitation in the kernel support for plat-versatile,
which contains the secondary CPU startup code for the VExpress.

Basically, the secondary CPU startup code is preceded by the macro __INIT,
which causes the code to be freed in free_initmem() during kernel_init().

This means that any attempt at hot-booting CPUs in the guest results in
VCPUs jumping to a memory address that was freed, after which the VCPU
behaves erratically, as can be expected.

With this patch applied, we use __CPUINIT instead of __INIT, so that
the right thing happens:
under CONFIG_HOTPLUG_CPU, the secondary CPU startup code is not freed,
the secondary VCPUs start successfully, and it's all gardens and blue skies.

Tested successfully using the ARM fast models for the Cortex-A15.

--
Claudio Fontana (1):
  ARM: plat-versatile: move secondary CPU startup code out of .init.

 arch/arm/plat-versatile/headsmp.S | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

-- 
1.7.12.1

^ permalink raw reply	[flat|nested] 10+ messages in thread
end of thread, other threads:[~2012-12-30  4:09 UTC | newest]

Thread overview: 10+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2012-11-27  8:39 [PATCH 0/1 RESEND 2] ARM: plat-versatile: move secondary CPU startup out of .init Claudio Fontana
2012-11-27  8:39 ` Claudio Fontana
2012-11-27  8:43 ` [PATCH 1/1 " Claudio Fontana
2012-11-27  8:43   ` Claudio Fontana
2012-12-12  8:59 ` [PATCH RESEND 3] ARM: plat-versatile: move secondary CPU startup into cpuinit Claudio Fontana
2012-12-12  8:59   ` Claudio Fontana
2012-12-18  8:42 ` [PATCH RESEND 4] " Claudio Fontana
2012-12-18  8:42   ` Claudio Fontana
2012-12-30  4:09   ` Christoffer Dall
2012-12-30  4:09     ` Christoffer Dall

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