From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-oi1-x231.google.com (mail-oi1-x231.google.com [IPv6:2607:f8b0:4864:20::231]) by sourceware.org (Postfix) with ESMTPS id 2F00A3857366 for ; Wed, 27 Jul 2022 16:22:56 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 2F00A3857366 Received: by mail-oi1-x231.google.com with SMTP id i4so11351083oif.2 for ; Wed, 27 Jul 2022 09:22:56 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=SnOPnUmAdvjK6yj9YVREDaQ7mC1w2CYqcTVTdMVGH6Q=; b=MWGb8ltrVeo6RMAM5tuntggd4J94xyNYgn7ccjJoAjBUed7mGg1S1dR1SILYZxb+5E iF7oXpB73pyWlP8dpcnYnVPFEb49lUa3bPqj8AD0Grvb1PXb0/SGe306kaUTMnlHMRLT PumKFWPV0mL5JbK7HE0gLAtQNqqEGseKNi8AxkngN8VLkStX/VuVD8iuf8rsu3MOZTGf biWNvVY8OZYUFZnJ6CugklvqzENIecc/kBFnXH44nLtP928PgtJiU6kx0y8B6MoIFjra ROv6Yc0b4nGpFsbYdZArO8QB9/E0BM3Nq1GeTguwc4FSpLDRXkdeZn0yth8GNZyn63oY Y01Q== X-Gm-Message-State: AJIora97BqVDu+2/5oTcDLokJSdyyhjvhlrN3NFr8wV3FBNQhHHRIluW bbatCYUHgqHz1Z5hXIZRRTdepd/CjUk1MZHgatznYI7HoH2jorJo X-Google-Smtp-Source: AGRyM1tg1m0up6WwprfzIH5JGZXHid4+7XoWb/i156Ypm8MuequLwVnjd/7UD6Idluq3N8X8ikx9pD56T/t41DNzCIQ= X-Received: by 2002:a05:6808:170b:b0:335:1807:e4a2 with SMTP id bc11-20020a056808170b00b003351807e4a2mr2172017oib.89.1658938975496; Wed, 27 Jul 2022 09:22:55 -0700 (PDT) MIME-Version: 1.0 References: <20220727065841.2140573-1-goldstein.w.n@gmail.com> <20220727121023.2146666-1-goldstein.w.n@gmail.com> In-Reply-To: From: Noah Goldstein Date: Thu, 28 Jul 2022 00:22:44 +0800 Message-ID: Subject: Re: [PATCH v2] NEWS: Add entry for x86-64 ISA level build To: Joseph Myers Cc: GNU C Library Content-Type: text/plain; charset="UTF-8" X-Spam-Status: No, score=-3.1 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, FREEMAIL_FROM, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP, URIBL_BLACK autolearn=no autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 27 Jul 2022 16:22:57 -0000 On Thu, Jul 28, 2022 at 12:12 AM Joseph Myers wrote: > > On Wed, 27 Jul 2022, Noah Goldstein via Libc-alpha wrote: > > > +* Support building x86-64 with multiple ISA levels has been added. > > + Higher ISA levels will use better optimized functions in the dynamic > > + loader and non-multiarch build as well as reduce the size of libc.so. > > I don't think "with multiple ISA levels" is very meaningful to users. > How is "with multiple ISA levels" different from the multi-arch feature > that's been present for many years - I think it could easily be read as a > description of that longstanding existing feature? You need a description > that makes clear to users who aren't following glibc development what the > actual new feature is (i.e. that if you build with a compiler that > defaults to a newer ISA level such as -march=x86-64-v2, the resulting libc > will use corresponding optimized implementations and omit the versions > only relevant on older processors, if I'm understanding the feature > correctly). That's fair. Not really sure this needs a NEWS entry at the end of the day. It's not really directly visible. The only meaningful change is that there won't be any legacy sse code so potentially (with great care) a user could entirely omit `vzeroupper`. Adhemerval do you think this needs an entry or is it too behind the scenes? > > -- > Joseph S. Myers > joseph@codesourcery.com