Messages in this thread | | | Date | Tue, 27 Nov 2012 09:39:13 +0100 | From | Claudio Fontana <> | Subject | [PATCH 0/1 RESEND 2] ARM: plat-versatile: move secondary CPU startup out of .init. |
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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
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