From mboxrd@z Thu Jan 1 00:00:00 1970 From: maxime.ripard@free-electrons.com (Maxime Ripard) Date: Wed, 23 Oct 2013 12:28:09 +0100 Subject: [Add SMP support for Allwinner A20: PATCH V5 3/3] Add arch count timer node in dts for Allwinner A20(sunxi 7i). In-Reply-To: <1382027827-10080-4-git-send-email-cinifr@gmail.com> References: <1382027827-10080-1-git-send-email-cinifr@gmail.com> <1382027827-10080-4-git-send-email-cinifr@gmail.com> Message-ID: <20131023112809.GX3041@lukather> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org 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 -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 836 bytes Desc: Digital signature URL: