From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751283AbdFAGIa (ORCPT ); Thu, 1 Jun 2017 02:08:30 -0400 Received: from mail-wm0-f67.google.com ([74.125.82.67]:36849 "EHLO mail-wm0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751118AbdFAGI2 (ORCPT ); Thu, 1 Jun 2017 02:08:28 -0400 Date: Thu, 1 Jun 2017 08:08:24 +0200 From: Ingo Molnar To: Josh Poimboeuf Cc: x86@kernel.org, linux-kernel@vger.kernel.org, live-patching@vger.kernel.org, Linus Torvalds , Andy Lutomirski , Jiri Slaby , "H. Peter Anvin" , Peter Zijlstra Subject: Re: [RFC PATCH 00/10] x86: undwarf unwinder Message-ID: <20170601060824.wv2go3adbvx5ptmt@gmail.com> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20170113 (1.7.2) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Josh Poimboeuf wrote: > Here's the contents of the undwarf.txt file which explains the 'why' in > more detail: Ok, so the code quality looks pretty convincing to me - the new core 'undwarf' unwinder code is a _lot_ more readable than any of the Dwarf based attempts before. That we control the debug info generation at build time is icing on the cake to me. One thing I'd like to see on the list of benefits side of the equation is a size comparison of kernel .text, with frame pointers vs. undwarf, on 64-bit kernels. Being able to generate more optimal code in the hottest code paths of the kernel is the _real_, primary upstream kernel benefit of a different debuginfo method - which has to be weighed against the pain of introducing a new unwinder. But this submission does not talk about that aspect at all, which should be fixed I think. Thanks, Ingo