Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757074AbcCaNDY (ORCPT ); Thu, 31 Mar 2016 09:03:24 -0400 Received: from mx2.suse.de ([195.135.220.15]:34949 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756374AbcCaNDW (ORCPT ); Thu, 31 Mar 2016 09:03:22 -0400 Date: Thu, 31 Mar 2016 15:03:16 +0200 (CEST) From: Miroslav Benes To: Josh Poimboeuf cc: Jiri Kosina , Jessica Yu , linux-kernel@vger.kernel.org, live-patching@vger.kernel.org, Vojtech Pavlik Subject: Re: [RFC PATCH v1.9 07/14] x86/stacktrace: add function for detecting reliable stack traces In-Reply-To: <1f8c648ed8b8eb49a75f5a6cacf8b7ca76f44fa9.1458933243.git.jpoimboe@redhat.com> Message-ID: References: <1f8c648ed8b8eb49a75f5a6cacf8b7ca76f44fa9.1458933243.git.jpoimboe@redhat.com> User-Agent: Alpine 2.00 (LNX 1167 2008-08-23) 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 Content-Length: 917 Lines: 23 On Fri, 25 Mar 2016, Josh Poimboeuf wrote: > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig > index 2dc18605..76274b8 100644 > --- a/arch/x86/Kconfig > +++ b/arch/x86/Kconfig > @@ -138,6 +138,7 @@ config X86 > select HAVE_PERF_REGS > select HAVE_PERF_USER_STACK_DUMP > select HAVE_REGS_AND_STACK_ACCESS_API > + select HAVE_RELIABLE_STACKTRACE if X86_64 && FRAME_POINTER I understand we have to rely on frame pointer for now. Do you plan to switch to dwarf unwinder one day in the future? IOW is there a plan to implement dwarf stuff generation in objtool and then to have a dwarf-based stack unwinder upstream and to use it for live patching? We have FRAME_POINTER unset in SLES for performance reasons (there was some 5 percent slowdown measured in the past. However we should redo the experiments.) and one day we'd really like to switch to upstream from kgraft :). So I'm just asking. Miroslav