From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 32738 invoked by alias); 30 Dec 2014 10:12:34 -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 32727 invoked by uid 89); 30 Dec 2014 10:12:33 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-2.0 required=5.0 tests=AWL,BAYES_00,SPF_HELO_PASS,SPF_PASS,T_RP_MATCHES_RCVD autolearn=ham version=3.3.2 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; Tue, 30 Dec 2014 10:12:32 +0000 Received: from int-mx09.intmail.prod.int.phx2.redhat.com (int-mx09.intmail.prod.int.phx2.redhat.com [10.5.11.22]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id sBUACTmx031771 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Tue, 30 Dec 2014 05:12:29 -0500 Received: from [127.0.0.1] (ovpn01.gateway.prod.ext.ams2.redhat.com [10.39.146.11]) by int-mx09.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id sBUACFQW013996; Tue, 30 Dec 2014 05:12:21 -0500 Message-ID: <54A27A7E.4070200@redhat.com> Date: Tue, 30 Dec 2014 10:12:00 -0000 From: Pedro Alves User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.3.0 MIME-Version: 1.0 To: "Maciej W. Rozycki" CC: Yao Qi , gdb-patches@sourceware.org Subject: Re: [PATCH] MIPS: Handle the DSP registers for bare metal References: <1418909149-29929-1-git-send-email-yao@codesourcery.com> <54930ED2.1080806@redhat.com> <87r3vwqooq.fsf@codesourcery.com> <5494098B.7080002@redhat.com> In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-SW-Source: 2014-12/txt/msg00678.txt.bz2 On 12/30/2014 01:15 AM, Maciej W. Rozycki wrote: > On Fri, 19 Dec 2014, Pedro Alves wrote: > >>>> > >> Took me a bit to grok this, but this is adding slack for ACXn, right? >>> > > >>> > > Sorry, what do you mean by "slack" here? Is it "gap" or something else? >> > >> > Yes, "gap". >> > >>> > > The offsets of DSP registers are different on linux and bare metal, so >>> > > this patch gives the correct offset or layout to them. >> > >> > The proper solution for this issue is to decouple GDB's internal >> > register numbers from the target's g/G packet layout, which is exactly >> > what happens when you have a description -- GDB uses the offsets found >> > in the target description. And you're touching code that is parsing a >> > description, so the real issue should be in the target description. > I'm not sure offhand whether the piece of patch proposed you refer to > here is correct or not, but the overall scope of this and the other patch > Yao has mentioned yet outstanding is support for legacy bare-metal RSP > stubs that have no notion of target descriptions and may even predate > GDB's support for these descriptions, and yet they want to make all > processor registers available for inspection and modification by GDB. > This code comes from MIPS UK and dates back to early 2000s and I think it > would be good having it upstream so that standard GDB can talk to these > stubs. The fixed layout of the g/G packet and corresponding p/P packet > offsets have been set by the bare-metal SDE toolchain years ago. The way to handle that is still through target descriptions -- if a target doesn't send a target description, GDB maps known layouts to built-in target descriptions. See mips_register_g_packet_guesses. [snip interesting background info] Thanks for all that. -- Pedro Alves