From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pj1-x1036.google.com (mail-pj1-x1036.google.com [IPv6:2607:f8b0:4864:20::1036]) by sourceware.org (Postfix) with ESMTPS id ABEAC3858286 for ; Fri, 15 Jul 2022 01:17:31 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org ABEAC3858286 Received: by mail-pj1-x1036.google.com with SMTP id o5-20020a17090a3d4500b001ef76490983so4695681pjf.2 for ; Thu, 14 Jul 2022 18:17:31 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:subject:to:cc:references:in-reply-to :mime-version:message-id:content-transfer-encoding; bh=nfJx8szvxpAumqie3qdvyskTXcrkxNNhi3meRmvRgBw=; b=VaunYWIL2VoGkIWgWAYMuevz/L2ZBCdXa/fX1eqK4JQJZ33eM6G2Mu/2WSoR6kYjgq C9ajjt2maC+z9XNi8MLChc7YvnTRXXS3Xzy8vkn+Rr+bRByJqSkB7FubZmN8hogv6Hu2 Wzzs5aydvGF7Ke6pzI/XocFOSOtPtB8fFdeyKbYv2i6XgQ50I9h1UbL5N/e01xYidQPp iO1noD5uEuzN+yTZdwIgpUVE5AR6pMPmvSdyxX2s5C/h73/JeetUTMh0I1lO7nrZi2L0 urFOpu9kEquZHINJhgJaBKKugxdN3gHyZQ50JLw6K2xzJoyRV/iPOvLVP9dFzkoJlC1V dSuQ== X-Gm-Message-State: AJIora8DLS+3+RKhf0hcGkbt3xuTyqumHOb0oXzrSzzUJ0HXGj+RA7mZ SaqrZMdIIUAqwNprgmeQLhA= X-Google-Smtp-Source: AGRyM1sHnFlsaFGqT4bufSjNvAS/0/NjyKSVvuKQBCzgEhsyPjBMyYDDKlpFaifVuzzmtu1WlC9RTQ== X-Received: by 2002:a17:902:ccc7:b0:16c:484f:4c69 with SMTP id z7-20020a170902ccc700b0016c484f4c69mr11544540ple.118.1657847850565; Thu, 14 Jul 2022 18:17:30 -0700 (PDT) Received: from localhost (61-68-63-70.tpgi.com.au. [61.68.63.70]) by smtp.gmail.com with ESMTPSA id x9-20020a170902a38900b0016c0c82e85csm2111979pla.75.2022.07.14.18.17.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 14 Jul 2022 18:17:29 -0700 (PDT) Date: Fri, 15 Jul 2022 11:17:24 +1000 From: Nicholas Piggin Subject: Re: [PATCH Linux] powerpc: add documentation for HWCAPs To: Florian Weimer , Segher Boessenkool Cc: gcc@gcc.gnu.org, libc-alpha@sourceware.org, linuxppc-dev@lists.ozlabs.org, Paul E Murphy References: <20220524093828.505575-1-npiggin@gmail.com> <87ee0juukf.fsf@oldenburg.str.redhat.com> <20220524183236.GJ25951@gate.crashing.org> In-Reply-To: <20220524183236.GJ25951@gate.crashing.org> MIME-Version: 1.0 Message-Id: <1657846871.9qtz2ahf6c.astroid@bobo.none> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Spam-Status: No, score=0.7 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, FREEMAIL_FROM, RCVD_IN_BARRACUDACENTRAL, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP, T_SCC_BODY_TEXT_LINE 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: gcc@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 15 Jul 2022 01:17:34 -0000 Excerpts from Segher Boessenkool's message of May 25, 2022 4:32 am: > On Tue, May 24, 2022 at 11:52:00AM +0200, Florian Weimer wrote: >> * Nicholas Piggin: >>=20 >> > +2. Facilities >> > +------------- >> > +The Power ISA uses the term "facility" to describe a class of instruc= tions, >> > +registers, interrupts, etc. The presence or absence of a facility ind= icates >> > +whether this class is available to be used, but the specifics depend = on the >> > +ISA version. For example, if the VSX facility is available, the VSX >> > +instructions that can be used differ between the v3.0B and v3.1B ISA >> > +verstions. >>=20 >> The 2.07 ISA manual also has categories. ISA 3.0 made a lot of things >> mandatory. It may make sense to clarify that feature bits for mandatory >> aspects of the ISA are still set, to help with backwards compatibility. >=20 > Linux runs on ISA 1.xx and ISA 2.01 machines still. "Category" wasn't > invented for either yet either, but similar concepts did exist of > course. Not sure what to say about this. It now also has "Compliancy Subset" although maybe that's more like a set of features rather than incompatible features or modes such as some of the category stuff seems to be. I'll try add something. Thanks, Nick