From mboxrd@z Thu Jan 1 00:00:00 1970 Received: with ECARTIS (v1.0.0; list linux-mips); Wed, 13 Jan 2016 21:49:18 +0100 (CET) Received: from bombadil.infradead.org ([198.137.202.9]:55767 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by eddie.linux-mips.org with ESMTP id S27009601AbcAMUtQifwCd (ORCPT ); Wed, 13 Jan 2016 21:49:16 +0100 Received: from j217066.upc-j.chello.nl ([24.132.217.66] helo=twins) by bombadil.infradead.org with esmtpsa (Exim 4.80.1 #2 (Red Hat Linux)) id 1aJSLX-0007FY-QO; Wed, 13 Jan 2016 20:48:48 +0000 Received: by twins (Postfix, from userid 1000) id D8D1F1257A0D8; Wed, 13 Jan 2016 21:48:44 +0100 (CET) Date: Wed, 13 Jan 2016 21:48:44 +0100 From: Peter Zijlstra To: Leonid Yegoshin Cc: Will Deacon , "Michael S. Tsirkin" , linux-kernel@vger.kernel.org, Arnd Bergmann , linux-arch@vger.kernel.org, Andrew Cooper , Russell King - ARM Linux , virtualization@lists.linux-foundation.org, Stefano Stabellini , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Joe Perches , David Miller , linux-ia64@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, sparclinux@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-metag@vger.kernel.org, linux-mips@linux-mips.org, x86@kernel.org, user-mode-linux-devel@lists.sourceforge.net, adi-buildroot-devel@lists.sourceforge.net, linux-sh@vger.kernel.org, linux-xtensa@linux-xtensa.org, xen-devel@lists.xenproject.org, Ralf Baechle , Ingo Molnar , ddaney.cavm@gmail.com, james.hogan@imgtec.com, Michael Ellerman , Paul McKenney Subject: Re: [v3,11/41] mips: reuse asm-generic/barrier.h Message-ID: <20160113204844.GV6357@twins.programming.kicks-ass.net> References: <1452426622-4471-12-git-send-email-mst@redhat.com> <56945366.2090504@imgtec.com> <20160112092711.GP6344@twins.programming.kicks-ass.net> <20160112102555.GV6373@twins.programming.kicks-ass.net> <20160112104012.GW6373@twins.programming.kicks-ass.net> <20160112114111.GB15737@arm.com> <569565DA.2010903@imgtec.com> <20160113104516.GE25458@arm.com> <56969F4B.7070001@imgtec.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <56969F4B.7070001@imgtec.com> User-Agent: Mutt/1.5.21 (2012-12-30) Return-Path: X-Envelope-To: <"|/home/ecartis/ecartis -s linux-mips"> (uid 0) X-Orcpt: rfc822;linux-mips@linux-mips.org Original-Recipient: rfc822;linux-mips@linux-mips.org X-archive-position: 51092 X-ecartis-version: Ecartis v1.0.0 Sender: linux-mips-bounce@linux-mips.org Errors-to: linux-mips-bounce@linux-mips.org X-original-sender: peterz@infradead.org Precedence: bulk List-help: List-unsubscribe: List-software: Ecartis version 1.0.0 List-Id: linux-mips X-List-ID: linux-mips List-subscribe: List-owner: List-post: List-archive: X-list: linux-mips On Wed, Jan 13, 2016 at 11:02:35AM -0800, Leonid Yegoshin wrote: > I ask HW team about it but I have a question - has it any relationship with > replacing MIPS SYNC with lightweight SYNCs (SYNC_WMB etc)? Of course. If you cannot explain the semantics of the primitives you introduce, how can we judge the patch. This barrier business is hard enough as it is, but magic unexplained hardware makes it impossible. Rest assured, you (MIPS) isn't the first (nor likely the last) to go through all this. We've had these discussions (and to a certain extend are still having them) for x86, PPC, Alpha, ARM, etc.. Any every time new barriers instructions get introduced we had better have a full and comprehensive explanation to go along with them.