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 53404C433F5 for ; Tue, 24 May 2022 18:36:08 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4L72vp517lz3cFL for ; Wed, 25 May 2022 04:36:06 +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 4L72vM70j1z2y0B for ; Wed, 25 May 2022 04:35:43 +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 24OIWbnb027426; Tue, 24 May 2022 13:32:37 -0500 Received: (from segher@localhost) by gate.crashing.org (8.14.1/8.14.1/Submit) id 24OIWai1027425; Tue, 24 May 2022 13:32:36 -0500 X-Authentication-Warning: gate.crashing.org: segher set sender to segher@kernel.crashing.org using -f Date: Tue, 24 May 2022 13:32:36 -0500 From: Segher Boessenkool To: Florian Weimer Subject: Re: [PATCH Linux] powerpc: add documentation for HWCAPs Message-ID: <20220524183236.GJ25951@gate.crashing.org> References: <20220524093828.505575-1-npiggin@gmail.com> <87ee0juukf.fsf@oldenburg.str.redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87ee0juukf.fsf@oldenburg.str.redhat.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: gcc@gcc.gnu.org, libc-alpha@sourceware.org, linuxppc-dev@lists.ozlabs.org, Nicholas Piggin , Paul E Murphy Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Tue, May 24, 2022 at 11:52:00AM +0200, Florian Weimer wrote: > * Nicholas Piggin: > > > +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 > > +verstions. > > 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. 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. Segher