From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id AEB65C43334 for ; Fri, 15 Jul 2022 15:01:53 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4Lkvhc0RY6z3c9g for ; Sat, 16 Jul 2022 01:01:52 +1000 (AEST) Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=kernel.crashing.org (client-ip=63.228.1.57; helo=gate.crashing.org; envelope-from=segher@kernel.crashing.org; receiver=) Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) by lists.ozlabs.org (Postfix) with ESMTP id 4Lkvh84Jc9z3c1c for ; Sat, 16 Jul 2022 01:01:28 +1000 (AEST) 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 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-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Florian Weimer , gcc@gcc.gnu.org, libc-alpha@sourceware.org, Paul E Murphy , linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" 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