From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) by sourceware.org (Postfix) with ESMTP id E199C3857BBF for ; Fri, 15 Jul 2022 15:02:30 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org E199C3857BBF Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=kernel.crashing.org Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=kernel.crashing.org Received: from gate.crashing.org (localhost.localdomain [127.0.0.1]) by gate.crashing.org (8.14.1/8.14.1) with ESMTP id 26FEvHIb021914; Fri, 15 Jul 2022 09:57:17 -0500 Received: (from segher@localhost) by gate.crashing.org (8.14.1/8.14.1/Submit) id 26FEvHJA021913; Fri, 15 Jul 2022 09:57:17 -0500 X-Authentication-Warning: gate.crashing.org: segher set sender to segher@kernel.crashing.org using -f Date: Fri, 15 Jul 2022 09:57:17 -0500 From: Segher Boessenkool To: Nicholas Piggin Cc: linuxppc-dev@lists.ozlabs.org, libc-alpha@sourceware.org, gcc@gcc.gnu.org, Paul E Murphy , Peter Bergner , Michael Ellerman , Florian Weimer Subject: Re: [PATCH v2] powerpc: add documentation for HWCAPs Message-ID: <20220715145717.GZ25951@gate.crashing.org> References: <20220715012636.165948-1-npiggin@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220715012636.165948-1-npiggin@gmail.com> User-Agent: Mutt/1.4.2.3i X-Spam-Status: No, score=-3.1 required=5.0 tests=BAYES_00, JMQ_SPF_NEUTRAL, KAM_DMARC_STATUS, SPF_HELO_PASS, SPF_PASS, TXREP 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: Fri, 15 Jul 2022 15:02:32 -0000 On Fri, Jul 15, 2022 at 11:26:36AM +1000, Nicholas Piggin wrote: > Take the arm64 HWCAP documentation file and adjust it for powerpc. > > Signed-off-by: Nicholas Piggin Reviewed-by: Segher Boessenkool > +2. Facilities > +------------- > + > +The Power ISA uses the term "facility" to describe a class of instructions, > +registers, interrupts, etc. The presence or absence of a facility indicates > +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 > +versions. The term "facility" is never defined in the architecture documents, so the common language meaning applies, which google says is "a place, amenity, or piece of equipment provided for a particular purpose", which fits your explanation well. > +3. Categories > +------------- > + > +The Power ISA before v3.0 uses the term "category" to describe certain > +classes of instructions and operating modes which may be optional or > +mutually exclusive, the exact meaning of the HWCAP flag may depend on > +context, e.g., the presence of the BOOKE feature implies that the server > +category is not implemented. Since ISA 3.0 the preface says The resulting architecture included [...] and optional application- specific facilities (categories) as extensions to a pervasive base architecture. which fits your explanation. Thanks for improving the documentation! Segher