From mboxrd@z Thu Jan 1 00:00:00 1970 From: will.deacon@arm.com (Will Deacon) Date: Fri, 30 May 2014 19:02:12 +0100 Subject: [PATCH v3 2/2] ARM : change fixmap mapping region to support 32 CPUs In-Reply-To: References: <1397559967-26050-1-git-send-email-sdu.liu@huawei.com> <1397559967-26050-3-git-send-email-sdu.liu@huawei.com> Message-ID: <20140530180212.GF22895@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Fri, May 30, 2014 at 04:33:46PM +0100, Rob Herring wrote: > On Tue, Apr 15, 2014 at 6:06 AM, Liu Hua wrote: > > In 32-bit ARM systems, the fixmap mapping region can support > > no more than 14 CPUs(total: 896k; one CPU: 64K). And we can > > configure NR_CPUS up to 32. So there is a mismatch. > > > > This patch moves fixmapping region downwards to region > > 0xffc00000-0xffe00000. Then the fixmap mapping region can > > support up to 32 CPUs > > Ugg, this series breaks using fixmap for anything other than kmap > since 32 cpus requires all 2MB of the region and nothing is left. > There's work in flight to support early_ioremap, early console, and RO > text patching which all use the fixmap region. > > There's a couple of options to solve this: > > - Only support up to 16 cpus. It could be anywhere between 17-31, but > that seems somewhat unlikely. Are we really ever going to see 32-bit > 32 core systems? I'd be fine with restricting the limit to 16 CPUs. Will