From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 12981 invoked by alias); 2 Nov 2016 22:33:10 -0000 Mailing-List: contact libc-alpha-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: libc-alpha-owner@sourceware.org Received: (qmail 12971 invoked by uid 89); 2 Nov 2016 22:33:10 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-4.2 required=5.0 tests=BAYES_00,RP_MATCHES_RCVD,SPF_HELO_PASS autolearn=ham version=3.3.2 spammy=detection, pureuserland, dl_hwcap, pure-userland X-HELO: mx1.redhat.com Message-ID: <1478125983.7146.733.camel@localhost.localdomain> Subject: Re: [RFC][PATCH 0/2] Make sparcv8 work again on cas enabled hardware From: Torvald Riegel To: David Miller Cc: andreas@gaisler.com, libc-alpha@sourceware.org, adhemerval.zanella@linaro.org, carlos@redhat.com, software@gaisler.com Date: Wed, 02 Nov 2016 22:33:00 -0000 In-Reply-To: <20161102.113238.241484722789762790.davem@davemloft.net> References: <1478018801.7146.655.camel@localhost.localdomain> <20161101.125117.2228115672691137607.davem@davemloft.net> <1478081121.7146.673.camel@localhost.localdomain> <20161102.113238.241484722789762790.davem@davemloft.net> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 7bit X-SW-Source: 2016-11/txt/msg00090.txt.bz2 On Wed, 2016-11-02 at 11:32 -0400, David Miller wrote: > From: Torvald Riegel > > Or do you intend to write sparc-specific versions of all the concurrent > > data structures that are process-shared? > > This would be necessary anyways, if we have two modes. One that does > the pure-userland code path and one that does the kernel helper code > path. All the other archs that use a kernel helper for CAS don't need it. If you can call the helper in the atomic operations, you won't need a new algorithm except if you wanted to optimize the generic one. > Furthermore, sparc specific versions are needed in any case since we > have the v9 detection even in the v8 libraries. Look at all of the > code that checks for v9 in the dl_hwcap mask when deciding which > atomic operation to use. Or are you talking about the implementation of the atomic operations?