From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 120740 invoked by alias); 14 Apr 2016 11:33:59 -0000 Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org Received: (qmail 120719 invoked by uid 89); 14 Apr 2016 11:33:58 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.9 required=5.0 tests=BAYES_00,KAM_LAZY_DOMAIN_SECURITY,RP_MATCHES_RCVD,SPF_HELO_PASS autolearn=ham version=3.3.2 spammy=Hx-languages-length:1507, ABC, family, Advanced X-HELO: mx1.redhat.com Received: from mx1.redhat.com (HELO mx1.redhat.com) (209.132.183.28) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with (AES256-GCM-SHA384 encrypted) ESMTPS; Thu, 14 Apr 2016 11:33:48 +0000 Received: from int-mx14.intmail.prod.int.phx2.redhat.com (int-mx14.intmail.prod.int.phx2.redhat.com [10.5.11.27]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id D91A97822C; Thu, 14 Apr 2016 11:33:46 +0000 (UTC) Received: from [127.0.0.1] (ovpn01.gateway.prod.ext.phx2.redhat.com [10.5.9.1]) by int-mx14.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id u3EBXjWA017114; Thu, 14 Apr 2016 07:33:45 -0400 Subject: Re: [PATCH V2 0/2] Split tdesc_(amd64|i386)_mpx into tdesc(amd64|i386)_mpx_* and tdesc(amd64|i386)_avx_mpx_* To: Yao Qi , Walfred Tedeschi References: <1457025942-23711-1-git-send-email-walfred.tedeschi@intel.com> <864mb4mqkm.fsf@gmail.com> Cc: brobecker@adacore.com, gdb-patches@sourceware.org From: Pedro Alves Message-ID: <570F8019.3060101@redhat.com> Date: Thu, 14 Apr 2016 11:33:00 -0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.7.1 MIME-Version: 1.0 In-Reply-To: <864mb4mqkm.fsf@gmail.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit X-SW-Source: 2016-04/txt/msg00324.txt.bz2 On 04/14/2016 11:29 AM, Yao Qi wrote: > Walfred Tedeschi writes: > >> CPU features can occur in any combination. The current assumption that >> feature "A" implies in feature "B" does not necessarily hold. >> >> This patch series construct an additional combination of the Intel(R) >> Memory Protection Extensions (MPX) with Intel(R) Advanced Vector >> Extensions (AVX). > > First of all, I am not against your patches. Just think a little more > after reading them... > > This reveals a problem in gdb target description. It doesn't scale very > well if processors have multiple different features, and features can be > combined differently. A processor family has three features A, B, and > C, and each processor implementation may have one, two or three of these > features. In gdb target description, we need to have many *.xml and *.c > files, for these combinations like, A, B, C, AB, AC, BC, and ABC. > > The root cause is that target description are static and pre-generated. > If the target description can be generated dynamically according to the > cpuid or AT_HWCAP, that would be simpler. In this way, we only have to > define target descriptions for feature A, B, and C, and GDB/GDBserver > combine them together in the runtime. I agree. This is not the first time this is suggested. If someone were to do it, I'd be in favor too. Thanks, Pedro Alves