From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752996AbdEFOY7 (ORCPT ); Sat, 6 May 2017 10:24:59 -0400 Received: from mx2.suse.de ([195.135.220.15]:53154 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751282AbdEFOYu (ORCPT ); Sat, 6 May 2017 10:24:50 -0400 Date: Sat, 6 May 2017 16:24:47 +0200 (CEST) From: Jiri Kosina X-X-Sender: jkosina@pobox.suse.cz To: Linus Torvalds cc: Jiri Slaby , Andrew Morton , live-patching@vger.kernel.org, Linux Kernel Mailing List , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , the arch/x86 maintainers , Josh Poimboeuf Subject: Re: [PATCH 7/7] DWARF: add the config option In-Reply-To: Message-ID: References: <20170505122200.31436-1-jslaby@suse.cz> <20170505122200.31436-7-jslaby@suse.cz> User-Agent: Alpine 2.20 (LSU 67 2015-01-07) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org [ adding Josh to CC ] On Fri, 5 May 2017, Linus Torvalds 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? As a datapoint -- we've been using dwarf unwinder in SUSE kernels since stone age, because we do not enable frame pointer, as it adds up to 10% of runtime slowdown for certain workloads, but we want reliable stacktraces so that we can actually debug user reports. Now that we have nicely reliable stacktraces thanks to Josh's objtool for FP-enabled builds, we'd like to bring comparably understandable traces also to non-FP enabled builds. > Put another way; the last time we did crazy stuff like this, it got > reverted. For a damn good reason, despite some people being in denial > about those reasons. There had been personal issues involved previously, no questions about that :) Thanks, -- Jiri Kosina SUSE Labs