From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 18832 invoked by alias); 26 Feb 2019 19:27:39 -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 18813 invoked by uid 89); 26 Feb 2019 19:27:38 -0000 Authentication-Results: sourceware.org; auth=none X-Spam-SWARE-Status: No, score=-1.9 required=5.0 tests=BAYES_00,RCVD_IN_DNSWL_NONE,SPF_PASS autolearn=ham version=3.3.2 spammy=communicate, HX-Received:a9f, Hx-spam-relays-external:209.85.222.65, H*RU:209.85.222.65 X-HELO: mail-ua1-f65.google.com Received: from mail-ua1-f65.google.com (HELO mail-ua1-f65.google.com) (209.85.222.65) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Tue, 26 Feb 2019 19:27:37 +0000 Received: by mail-ua1-f65.google.com with SMTP id a42so12986621uad.1 for ; Tue, 26 Feb 2019 11:27:36 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sifive.com; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=bkSyxOazp2FNImSOW2Vo3tSBRHyA6onX/Aq/evUs3Ok=; b=LPkFczJET8p2qpVVL5t1i5TCwp94Sdm4ST/jbJWjTur13jfTE5VORAZNL0heeLKLLR co/bxBkuLzZ7mJNdf+HjWsLxx99nd0pog9I3eaVHJIk9943pRe8STErYtcjqrGspM1l3 xuuUIpZW1rR+V5Fda0b7bcYu0MeO93AuT+jsEF2yzyLV6R0rqvx0GO5f8sEzKKu+Oedd 0/vOMs+jnzR0Y9ZwX0NfY+ixK6p8d0pLhRCvXUMwY0LG9rrGDZxV19VJ47o9PHlAFTG7 KLgBvIm7Dk1QaJu3Xj1/8+XFHiTmRH4ZnfGhJdMGp/5KWRCI8VCzhtsH+P9X2Ou6EKgu aI/Q== MIME-Version: 1.0 References: <20181108160745.24600-1-andrew.burgess@embecosm.com> <20181114145756.GM16539@embecosm.com> <87r2bz67ol.fsf@tromey.com> <20190223205116.GB15942@embecosm.com> <20190226050220.GA30982@adacore.com> <20190226182201.GH10887@embecosm.com> In-Reply-To: From: Jim Wilson Date: Tue, 26 Feb 2019 19:27:00 -0000 Message-ID: Subject: Re: [PATCH] gdb/riscv: Add target description support To: Andrew Burgess Cc: Joel Brobecker , Tom Tromey , gdb-patches@sourceware.org, Palmer Dabbelt , John Baldwin Content-Type: text/plain; charset="UTF-8" X-SW-Source: 2019-02/txt/msg00450.txt.bz2 On Tue, Feb 26, 2019 at 10:40 AM Jim Wilson wrote: > > (3) Renumbered fflags, frm, and fcsr as 66, 67, and 68. This is > > where the issues will appear for QEMU, Jim's QEMU patch had adopted > > the "new" default numbering which placed these registers after the > > floating point registers (so they had become 65, 66, and 67). qemu just assigns numbers to xml regs if they don't have them, incrementing by one for each reg. If we change the qemu xml files at the same time as we change the qemu gdbstub hooks, then qemu will always be internally consistent. These xml register numbers aren't user visible anywhere inside qemu, they are only used for communication with gdb. > > If we want backward compatibility then we should merge this GDB patch, > > and fix QEMU asap to avoid having two incompatible versions in the > > wild. I have no control over qemu. I can only suggest a patch, and ping it, and maybe in a few months it will get merged in. > > What I don't understand about all this is why QEMU appears to be > > discarding one of the big benefits of xml register descriptions; the > > ability to disconnect their register numbering from GDB's register > > numbering. I don't understand the comment. We still must have numbers for the registers, otherwise we can't communicate with gdb about them. But these xml register numbers don't affect the user or hardware register numbers, the qemu gdbstub converts between hardware register numbers and xml register numbers. > > Jim: I think your comments above indicate you want my fix merged, but > > if you could just confirm then I'll get it merged. Yes, I think this is OK. We can worry about qemu later. Jim