From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Rothwell Subject: Re: linux-next: build failure after merge of the rcu tree Date: Fri, 8 Jan 2016 15:08:50 +1100 Message-ID: <20160108150850.1ec97e78@canb.auug.org.au> References: <20160107195725.3a130b4d@canb.auug.org.au> <20160107180244.GR3818@linux.vnet.ibm.com> <20160108071932.060a9bcc@canb.auug.org.au> <20160107205220.GU3818@linux.vnet.ibm.com> <20160108013631.GA11410@fixme-laptop.cn.ibm.com> <20160108034157.GZ3818@linux.vnet.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20160108034157.GZ3818@linux.vnet.ibm.com> Sender: linux-kernel-owner@vger.kernel.org To: "Paul E. McKenney" Cc: Boqun Feng , linux-next@vger.kernel.org, linux-kernel@vger.kernel.org, Tejun Heo , Christoph Lameter List-Id: linux-next.vger.kernel.org Hi Paul, On Thu, 7 Jan 2016 19:41:57 -0800 "Paul E. McKenney" wrote: > > Indeed, I suspect that SRCU might not be the only thing that would like > static per-CPU variables. ;-) from include/linux/percpu-defs.h: * s390 and alpha modules require percpu variables to be defined as * weak to force the compiler to generate GOT based external * references for them. This is necessary because percpu sections * will be located outside of the usually addressable area. * * This definition puts the following two extra restrictions when * defining percpu variables. * * 1. The symbol must be globally unique, even the static ones. * 2. Static percpu variables cannot be defined inside a function. * * Archs which need weak percpu definitions should define * ARCH_NEEDS_WEAK_PER_CPU in asm/percpu.h when necessary. * * To ensure that the generic code observes the above two * restrictions, if CONFIG_DEBUG_FORCE_WEAK_PER_CPU is set weak * definition is used for all cases. so they can be static, but must be globally unique. -- Cheers, Stephen Rothwell sfr@canb.auug.org.au