From mboxrd@z Thu Jan 1 00:00:00 1970 From: magnus.damm@gmail.com (Magnus Damm) Date: Wed, 31 Jul 2013 15:00:08 +0900 Subject: ARM CPU Hotplug breakage on mach-shmobile and KZM9D In-Reply-To: <20130731010404.GJ17209@verge.net.au> References: <20130725010607.GB31464@verge.net.au> <20130730074939.GE7210@verge.net.au> <51F7CD67.6020209@windriver.com> <20130731010404.GJ17209@verge.net.au> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi Simon, Paul, On Wed, Jul 31, 2013 at 10:04 AM, Simon Horman wrote: > On Tue, Jul 30, 2013 at 10:27:51AM -0400, Paul Gortmaker wrote: >> On 13-07-30 03:49 AM, Simon Horman wrote: >> > [ Cc Paul Gortmaker ] >> > >> > On Thu, Jul 25, 2013 at 10:06:07AM +0900, Simon Horman wrote: >> >> On Thu, Jul 25, 2013 at 12:15:49AM +0900, Magnus Damm wrote: >> >>> Hi everyone, >> >>> >> >>> Bad news: CPU Hotplug on KZM9D seems broken on recent kernels. >> >>> >> >>> On renesas-next-20130710 or earlier I can perform the following: >> >>> >> >>> # echo 0 > /sys/devices/system/cpu/cpu1/online >> >>> CPU1: shutdown >> >>> # echo 1 > /sys/devices/system/cpu/cpu1/online >> >>> CPU1: Booted secondary processor >> >>> # >> >>> >> >>> While on more recent kernels the hotplug boot fails. This may be >> >>> related to the move to v3.11-rc. The tag renesas-next-20130710 >> >>> surprisingly seems to be the final kernel based on v3.10-rc before >> >>> jumping to v3.11-rc. >> >>> >> >>> I wonder, do other ARM platforms have working CPU Hotplug in v3.11-rc? >> >> >> >> I have a snowball that I could test if you think it would be useful. >> > >> > Unfortunately getting snowball to work turned out to be rather painful. >> > So instead I bisected the problem on the KZM9G (N.b: the D in the subject >> > seems to be incorrect :^) >> > >> > The result is that the following patch, added in v3.11-rc1, >> > appears to be the culprit. >> >> Double check that you have this commit present: >> --------------- >> commit 8c69d7af12265e5be9326110b695e010b47505bd >> Author: Stephen Warren >> Date: Fri Jul 5 22:59:42 2013 +0100 >> >> ARM: 7780/1: add missing linker section markup to head-common.S >> --------------- >> >> as I think you are reporting the same problem that it fixed. > > Unfortunately that does not seem to resolve the problem that I am seeing. > I have tried both v3.11-rc3 and 22f0a27367742f65130c0fb25ef00f7297e032c1 > with 8c69d7af12265e5be9326110b695e010b47505bd cherry picked on top and > in both cases I see: > > # echo 0 > /sys/devices/system/cpu/cpu1/online > CPU1: shutdown > # echo 1 > /sys/devices/system/cpu/cpu1/online > CPU1: failed to come online Thanks for your help. I've now tracked down this issue to the following fix: [PATCH] ARM: Fix memblock_reserve() to include stext Let me know if you think the code should be changed somehow. Cheers, / magnus