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 94C97C43334 for ; Fri, 15 Jul 2022 20:03:38 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4Ll2Nm61flz3cd6 for ; Sat, 16 Jul 2022 06:03:36 +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 4Ll2NC2b1bz2xrY for ; Sat, 16 Jul 2022 06:03:06 +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 26FJxqhD032654; Fri, 15 Jul 2022 14:59:52 -0500 Received: (from segher@localhost) by gate.crashing.org (8.14.1/8.14.1/Submit) id 26FJxp9u032647; Fri, 15 Jul 2022 14:59:51 -0500 X-Authentication-Warning: gate.crashing.org: segher set sender to segher@kernel.crashing.org using -f Date: Fri, 15 Jul 2022 14:59:51 -0500 From: Segher Boessenkool To: Tulio Magno Quites Machado Filho Subject: Re: [PATCH v2] powerpc: add documentation for HWCAPs Message-ID: <20220715195951.GA25951@gate.crashing.org> References: <20220715012636.165948-1-npiggin@gmail.com> <877d4euskv.fsf@linux.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <877d4euskv.fsf@linux.ibm.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, Nicholas Piggin , 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 03:41:20PM -0300, Tulio Magno Quites Machado Filho wrote: > Nicholas Piggin writes: > > > +PPC_FEATURE_ARCH_2_05 > > + The processor supports the v2.05 userlevel architecture. Processors > > + supporting later architectures also set this feature. > > I don't think this bit is enabled when processors support later architectures. > In my tests, this behavior started only with v2.06, i.e. processors that > support v2.07 enable bit v2.06, but do not enable bit v2.05. That is a usability problem. Can it be fixed, or will that create its own compatibility problems? In practice I mean. If it is, the C libraries could fix it up, for new programs, and then after a while the kernel can do the sane thing? How big is the problem, anyway? Is it only 2.05, or also 2.04, 2.03? Segher