From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752177AbdEJHqn (ORCPT ); Wed, 10 May 2017 03:46:43 -0400 Received: from mail-wr0-f194.google.com ([209.85.128.194]:36738 "EHLO mail-wr0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751081AbdEJHql (ORCPT ); Wed, 10 May 2017 03:46:41 -0400 Subject: Re: [PATCH 7/7] DWARF: add the config option To: Ingo Molnar , Linus Torvalds , Josh Poimboeuf References: <20170505122200.31436-1-jslaby@suse.cz> <20170505122200.31436-7-jslaby@suse.cz> <20170506071955.ssxpqs3g76l6eglf@gmail.com> Cc: Andrew Morton , live-patching@vger.kernel.org, Linux Kernel Mailing List , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , the arch/x86 maintainers From: Jiri Slaby Message-ID: <11aa34b6-b91b-ca77-7e81-765ea3815eb1@suse.cz> Date: Wed, 10 May 2017 09:46:38 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0 MIME-Version: 1.0 In-Reply-To: <20170506071955.ssxpqs3g76l6eglf@gmail.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/06/2017, 09:19 AM, Ingo Molnar wrote: > > * Linus Torvalds wrote: > >> On Fri, May 5, 2017 at 5:22 AM, Jiri Slaby wrote: >>> The DWARF unwinder is in place and ready. So introduce the config option >>> to allow users to enable it. It is by default off due to missing >>> assembly annotations. >> >> Who actually ends up using this? > > Also, why wasn't Josh Poimboeuf Cc:-ed, who de-facto maintains the x86 unwinding > code? I explicitly CCed Josh on 5/7 and 6/7 which touches the code. Besides that, I assumed he is implicitly CCed via live-patching@vger.kernel.org which is carbon-copied on each of the patches. > AFAICS this series is just repeating the old mistakes of the old Dwarf unwinders > of trusting GCC's unwinder data. So NAK for the time being on the whole approach: > > NAcked-by: Ingo Molnar OK, as the series stands now, we indeed do. Noteworthy, we, in SUSE, had no problems with this reliance for all the time we have been using the unwinder. Anyway, objtool is about to vaidate the DWARF data, generate it for assembly and potentially fix it if problems occur. Could you elaborate on what else would help you to change your stance? thanks, -- js suse labs