From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3t99SL23ZHzDvPG for ; Fri, 4 Nov 2016 16:31:46 +1100 (AEDT) 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 uA45So05009048 for ; Fri, 4 Nov 2016 01:31:44 -0400 Received: from e38.co.us.ibm.com (e38.co.us.ibm.com [32.97.110.159]) by mx0a-001b2d01.pphosted.com with ESMTP id 26gexf52we-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Fri, 04 Nov 2016 01:31:43 -0400 Received: from localhost by e38.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 3 Nov 2016 23:31:43 -0600 Subject: Re: [PATCH 1/3] powerpc: Emulation support for load/store instructions on LE To: Andrew Donnellan , Michael Ellerman References: <1478076783-2872-1-git-send-email-ravi.bangoria@linux.vnet.ibm.com> <1478076783-2872-2-git-send-email-ravi.bangoria@linux.vnet.ibm.com> <20161103080412.68240cda@kryten> <581ACDF2.1010409@linux.vnet.ibm.com> <8737j8opwb.fsf@concordia.ellerman.id.au> <581B110F.9050805@linux.vnet.ibm.com> Cc: chris@distroguy.com, aneesh.kumar@linux.vnet.ibm.com, ast@kernel.org, linux-kernel@vger.kernel.org, oss@buserror.net, paul.gortmaker@windriver.com, duwe@lst.de, Anton Blanchard , lsorense@csclub.uwaterloo.ca, bauerman@linux.vnet.ibm.com, oohall@gmail.com, naveen.n.rao@linux.vnet.ibm.com, linuxppc-dev@lists.ozlabs.org, paulus@samba.org, viro@zeniv.linux.org.uk, Ravi Bangoria From: Ravi Bangoria Date: Fri, 4 Nov 2016 11:01:30 +0530 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=windows-1252 Message-Id: <581C1D32.50108@linux.vnet.ibm.com> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Friday 04 November 2016 07:37 AM, Andrew Donnellan wrote: > On 03/11/16 21:27, Ravi Bangoria wrote: >> Yes, kernel-space hw-breakpoint feature is broken on LE without this. > > Is there any actual user-visible feature that depends on this, or is this solely for debugging and development purposes? > > It would of course be *nice* to have it in stable trees (particularly so we pick it up in distros) but I'm not convinced that enabling HW breakpoints on a platform where it has *never* worked qualifies as an "actual bug". > > (BTW many thanks for fixing this - I had a shot at it late last year but never quite got there!) Thanks Andrew, kprobe, uprobe, hw-breakpoint and xmon are the only user of emulate_step. Kprobe / uprobe single-steps instruction if they can't emulate it, so there is no problem with them. As I mention, hw-breakpoint is broken. However I'm not sure about xmon, I need to check that. So yes, there is no user-visible feature that depends on this. -Ravi