Messages in this thread | | | Date | Wed, 23 Oct 2013 12:28:09 +0100 | From | Maxime Ripard <> | Subject | Re: [Add SMP support for Allwinner A20: PATCH V5 3/3] Add arch count timer node in dts for Allwinner A20(sunxi 7i). |
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On Fri, Oct 18, 2013 at 12:37:07AM +0800, Fan Rong wrote: > Linux kernel usually use virtual arch timer for smp cpu tick. But the > arch timer register VCTOFF normally is very different between the two > cpus in A20 afer hardware reset, so SMP Cpus will see different time > tick. It will cause kernel crash currently. You have two choices to > fix it: 1 Simpley use physical arch timer, 2 Set VCTOFF to same value > for each cpu in bootloader. The first choice will cause some other > problem for kernel, especially for KVM, guest OS want to use virtual > arch timer. So the second choice is perfect. So if you want to use > arch timer for smp cpu tick, you must ensure you bootload have set > same VCTOFF for all cpus. >
Is your patchset working without that last patch?
I'm not really wanting to apply it right now.
It relies on a bootloader behaviour that is not implemented by any bootloader we have openly available right now. I will apply it after it's been merged in at least u-boot-sunxi.
Maxime
-- Maxime Ripard, Free Electrons Embedded Linux, Kernel and Android engineering http://free-electrons.com [unhandled content-type:application/pgp-signature] | |