From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 104669 invoked by alias); 16 Sep 2016 12:43:34 -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 104648 invoked by uid 89); 16 Sep 2016 12:43:33 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-2.1 required=5.0 tests=AWL,BAYES_00,RCVD_IN_DNSWL_LOW,RCVD_IN_SORBS_SPAM,SPF_PASS autolearn=ham version=3.3.2 spammy=H*x:2.5, H*UA:2.5 X-HELO: mx0a-001b2d01.pphosted.com Received: from mx0a-001b2d01.pphosted.com (HELO mx0a-001b2d01.pphosted.com) (148.163.156.1) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Fri, 16 Sep 2016 12:43:32 +0000 Received: from pps.filterd (m0098393.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.17/8.16.0.17) with SMTP id u8GChPUu076508 for ; Fri, 16 Sep 2016 08:43:30 -0400 Received: from e06smtp05.uk.ibm.com (e06smtp05.uk.ibm.com [195.75.94.101]) by mx0a-001b2d01.pphosted.com with ESMTP id 25gca27kfx-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Fri, 16 Sep 2016 08:43:30 -0400 Received: from localhost by e06smtp05.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 16 Sep 2016 13:43:27 +0100 Received: from d06dlp02.portsmouth.uk.ibm.com (9.149.20.14) by e06smtp05.uk.ibm.com (192.168.101.135) with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted; Fri, 16 Sep 2016 13:43:25 +0100 Received: from b06cxnps4074.portsmouth.uk.ibm.com (d06relay11.portsmouth.uk.ibm.com [9.149.109.196]) by d06dlp02.portsmouth.uk.ibm.com (Postfix) with ESMTP id 5A8772190063 for ; Fri, 16 Sep 2016 13:42:45 +0100 (BST) Received: from d06av02.portsmouth.uk.ibm.com (d06av02.portsmouth.uk.ibm.com [9.149.37.228]) by b06cxnps4074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id u8GChOKh24314278 for ; Fri, 16 Sep 2016 12:43:24 GMT Received: from d06av02.portsmouth.uk.ibm.com (localhost [127.0.0.1]) by d06av02.portsmouth.uk.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id u8GChOiv018303 for ; Fri, 16 Sep 2016 06:43:24 -0600 Received: from oc8523832656.ibm.com (dyn-9-152-213-149.boeblingen.de.ibm.com [9.152.213.149]) by d06av02.portsmouth.uk.ibm.com (8.14.4/8.14.4/NCO v10.0 AVin) with ESMTP id u8GChNQk018286; Fri, 16 Sep 2016 06:43:24 -0600 Received: by oc8523832656.ibm.com (Postfix, from userid 500) id AE052FE999; Fri, 16 Sep 2016 14:43:23 +0200 (CEST) Subject: Re: [PATCH 0/6] S390: Watchpoint enhancements and hardware breakpoints To: palves@redhat.com (Pedro Alves) Date: Fri, 16 Sep 2016 12:43:00 -0000 From: "Ulrich Weigand" Cc: arnez@linux.vnet.ibm.com (Andreas Arnez), gdb-patches@sourceware.org In-Reply-To: <8b5f2062-d755-672d-a899-781f77baa921@redhat.com> from "Pedro Alves" at Sep 15, 2016 03:11:02 PM MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 16091612-0020-0000-0000-00000201A309 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 16091612-0021-0000-0000-00001D8D5116 Message-Id: <20160916124323.AE052FE999@oc8523832656.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2016-09-16_07:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1609020000 definitions=main-1609160163 X-SW-Source: 2016-09/txt/msg00179.txt.bz2 Pedro Alves wrote: > On 09/15/2016 12:52 PM, Andreas Arnez wrote: > > This series adds some enhancements to the current s390-linux native > > support for watchpoints. It also adds hardware breakpoint support. > > > > While this is mostly an s390-specific series, it includes one > > common-code patch: patch #5, "linux-nat: Add function lwp_is_stepping". > > I'm looking for feedback on that. Comments to the s390-specific patches > > are certainly welcome as well. > > I'm curious on the need to disable hw breakpoints when single-stepping. This is more of a hardware restriction than a GDB issue. The problem is that s390 hardware doesn't really have a separate hardware single-step feature; to implement ptrace single-stepping, the kernel uses the s390 hardware breakpoint feature (in effect, enabling hardware breakpoints on the full address space, which will hit on the next instruction that is executed). This use of the feature by kernel single-stepping can conflict with explicit use of the same feature by GDB; that's why it is better to not attempt such explicit use while at the same time also requesting kernel single-stepping. Bye, Ulrich -- Dr. Ulrich Weigand GNU/Linux compilers and toolchain Ulrich.Weigand@de.ibm.com