From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 7644 invoked by alias); 3 Nov 2016 18:41:31 -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 7630 invoked by uid 89); 3 Nov 2016 18:41:31 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.9 required=5.0 tests=BAYES_00,RCVD_IN_DNSWL_NONE,SPF_PASS autolearn=ham version=3.3.2 spammy=Hx-languages-length:1379 X-HELO: mail-vk0-f50.google.com X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:subject:to:references:cc:from:message-id:date :user-agent:mime-version:in-reply-to:content-transfer-encoding; bh=DsBzwib/VqBNnnd9+oehAsWQBNTmos5QFmjb/Agn5Eo=; b=OSVwnTNHrDnxEeUcGz5+4ZSBOQoS2T1acpuB2+GOUE9E+6HYdO81EiuWQqMfX8sxTi gZNnS8zd+c+NW1qIGaZr913lppBsALmLTy1Vox5tK0Gz6q8wZtrYGx26FBCN6qneob+E iUxB1fCnkemjoBNBhKlM7MhtlknJTWDmLjQ59gJ/F2a77Hpt7Y4lhrBLzx7eKqXhtYG1 TSI/jzyGIhAeUR3XbmL9Ln2HlL1XeYbBh/dWWnkjPrRBnGhNwv3VZ+Vq/3R9qWEqzkRZ IjfUH1CfhVnDH6NhUOqZU3F1N6oOZcG/E9VFiuSUEEEBkIVqJsqT8946YKk9Lf1VZIXS MYJg== X-Gm-Message-State: ABUngvcfwAExd1to4uSCB70xYuwCq71KhCUl70zKzMgNO4YNGNV9wqG9MdQuRclhDYK8sChp X-Received: by 10.31.8.72 with SMTP id 69mr7872223vki.159.1478198479174; Thu, 03 Nov 2016 11:41:19 -0700 (PDT) Subject: Re: [RFC][PATCH 0/2] Make sparcv8 work again on cas enabled hardware To: David Miller , triegel@redhat.com References: <1478125983.7146.733.camel@localhost.localdomain> <20161102.225245.471656475226254205.davem@davemloft.net> <1478187561.7146.742.camel@localhost.localdomain> <20161103.132213.598669006383889263.davem@davemloft.net> Cc: andreas@gaisler.com, libc-alpha@sourceware.org, carlos@redhat.com, software@gaisler.com From: Adhemerval Zanella Message-ID: Date: Thu, 03 Nov 2016 18:41:00 -0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.3.0 MIME-Version: 1.0 In-Reply-To: <20161103.132213.598669006383889263.davem@davemloft.net> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 8bit X-SW-Source: 2016-11/txt/msg00113.txt.bz2 On 03/11/2016 15:22, David Miller wrote: > From: Torvald Riegel > Date: Thu, 03 Nov 2016 16:39:21 +0100 > >> Is there any difference between the additional CAS on a v8 and the CAS >> on a v9? If there should be none (eg, same instruciton encoding etc.), >> we wouldn't need a runtime check for this, would we? > > A quick look at binutils shows that the encoding appears to be the same. > >> That depends on whether we want to support sparc HW that does have a >> CAS. It's still not clear to me whether this is a goal, and if it's a >> goal, whether it's a goal for today or for some time in the future. > > I think there is value in supporting pure-v8, however painful it may > be. > > I personally don't like to see when we drop support for old systems on > the floor just because it's too inconvenient or cumbersome to keep > them working properly. In fact I see it should be one of the main reason for dropping support for old system. At least for current topic, it means add complete separate implementation for only one arch, where current work is aimed exactly to avoid it. It is more code to audit/test on very specific environments and adds more complexity while fixing the default implementation (should the patch touch as well the arch specific parts or just let it broke?).