From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 62128 invoked by alias); 24 Feb 2016 11:57:46 -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 62112 invoked by uid 89); 24 Feb 2016 11:57:45 -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,RP_MATCHES_RCVD,SPF_HELO_PASS autolearn=ham version=3.3.2 spammy=learned, rozycki, Hx-languages-length:1355, bps 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; Wed, 24 Feb 2016 11:57:44 +0000 Received: from int-mx11.intmail.prod.int.phx2.redhat.com (int-mx11.intmail.prod.int.phx2.redhat.com [10.5.11.24]) by mx1.redhat.com (Postfix) with ESMTPS id 955238E3CA; Wed, 24 Feb 2016 11:57:43 +0000 (UTC) Received: from [127.0.0.1] (ovpn01.gateway.prod.ext.phx2.redhat.com [10.5.9.1]) by int-mx11.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id u1OBvgVn015219; Wed, 24 Feb 2016 06:57:42 -0500 Message-ID: <56CD9AB6.6090300@redhat.com> Date: Wed, 24 Feb 2016 11:57:00 -0000 From: Pedro Alves User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 MIME-Version: 1.0 To: "Maciej W. Rozycki" CC: Luis Machado , gdb-patches@sourceware.org Subject: Re: [PATCH, v2] Expect SI_KERNEL or TRAP_BRKPT si_code values for MIPS breakpoint traps References: <1456145829-5052-1-git-send-email-lgustavo@codesourcery.com> <56CB0A42.70507@redhat.com> In-Reply-To: Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit X-SW-Source: 2016-02/txt/msg00720.txt.bz2 On 02/22/2016 04:19 PM, Maciej W. Rozycki wrote: > On Mon, 22 Feb 2016, Pedro Alves wrote: > >> I'd like to have a short paragraph in linux-nat.h about MIPS's behavior, >> below the ppc comment. If you look at the x86 table above, which cases get >> SI_KERNEL, and which don't? Single-step is not applicable, since the >> MIPS doesn't handle single-stepping itself (IIRC), but do we also get >> SI_KERNEL hardware bps and watchpoints, for example? > > As I previously noted the MIPS Linux port currently does not support > hardware breakpoints even though hardware may have them implemented > (they're optional). Only hardware watchpoints are supported right now. Ah. > You are right in that there's no OS single-stepping support defined in > the MIPS architecture and consequently Linux cannot support it on the MIPS > target. Only JTAG single-stepping is possible with MIPS hardware. Yeah. I see I missed a word, sorry. I meant "since the MIPS _kernel_ doesn't handle single-stepping itself". I was thinking about e.g., uprobes, and imagining that since the kernel needs to advance past uprobes-set breakpoints somehow, that the kernel could have learned to software single-step, and that that might have been hooked to PTRACE_SINGLESTEP. Thanks, Pedro Alves