From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751936AbeEGL6v (ORCPT ); Mon, 7 May 2018 07:58:51 -0400 Received: from pv33p00im-asmtp002.me.com ([17.142.194.251]:56113 "EHLO pv33p00im-asmtp002.me.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750913AbeEGL6t (ORCPT ); Mon, 7 May 2018 07:58:49 -0400 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2018-05-07_04:,, signatures=0 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 spamscore=0 clxscore=1011 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1707230000 definitions=main-1805070113 Date: Mon, 07 May 2018 12:57:44 +0200 From: damian To: Josh Poimboeuf Cc: peterz@infradead.org, linux-kernel@vger.kernel.org Subject: Re: Kernel build with gcc 8 a lot of warnings Message-id: <20180507105744.GA8586@zrhn9910b> Mail-followup-to: Josh Poimboeuf , peterz@infradead.org, linux-kernel@vger.kernel.org References: <20180505192112.GA18728@zrhn9910b> <20180507045453.leou4zypnlcck4vr@treble> MIME-version: 1.0 Content-type: text/plain; charset=us-ascii Content-disposition: inline In-reply-to: <20180507045453.leou4zypnlcck4vr@treble> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, 06. May 23:54, Josh Poimboeuf wrote: > On Sat, May 05, 2018 at 09:21:12PM +0200, damian wrote: > > Helllo together, > > > > Hello everybody, > > > > is something special to note when kernel build with gcc 8? I receive various warnings from the objtool: > > With GCC 7 works all fine. > > > > kernel/cgroup/cgroup.o: warning: objtool: parse_cgroup_root_flags()+0x40: sibling call from callable instruction with modified stack frame > > kernel/cgroup/cgroup.o: warning: objtool: cgroup_addrm_files()+0x2a3: sibling call from callable instruction with modified stack frame > > kernel/cgroup/cgroup.o: warning: objtool: cgroup_apply_control_enable()+0x20b: sibling call from callable instruction with modified stack frame > > kernel/cgroup/cgroup.o: warning: objtool: rebind_subsystems()+0x296: sibling call from callable instruction with modified stack frame > > kernel/cgroup/cgroup.o: warning: objtool: cgroup_sk_alloc_disable()+0x10: sibling call from callable instruction with modified stack frame > > kernel/cgroup/cgroup.o: warning: objtool: parse_cgroup_root_flags.cold.45()+0xa: call without frame pointer save/setup > > kernel/cgroup/cgroup.o: warning: objtool: cgroup_addrm_files.cold.46()+0x17: call without frame pointer save/setup > > kernel/cgroup/cgroup.o: warning: objtool: cgroup_apply_control_enable.cold.47()+0x24: call without frame pointer save/setup > > kernel/cgroup/cgroup.o: warning: objtool: rebind_subsystems.cold.48()+0x10: call without frame pointer save/setup > > kernel/cgroup/cgroup.o: warning: objtool: cgroup_sk_alloc_disable.cold.49()+0x7: call without frame pointer save/setup > > CC kernel/cgroup/stat.o > > CC [M] arch/x86/kvm/../../../virt/kvm/kvm_main.o > > arch/x86/kernel/acpi/boot.o: warning: objtool: acpi_register_lapic()+0x10: sibling call from callable instruction with modified stack frame > > arch/x86/kernel/acpi/boot.o: warning: objtool: acpi_map_cpu()+0x2c: sibling call from callable instruction with modified stack frame > > arch/x86/kernel/acpi/boot.o: warning: objtool: acpi_register_lapic.cold.6()+0x7: call without frame pointer save/setup > > arch/x86/kernel/acpi/boot.o: warning: objtool: acpi_map_cpu.cold.7()+0x7: call without frame pointer save/setup > > Thanks, this is a known issue with GCC 8 that I haven't gotten a chance > to fix yet. They're related to the fact that GCC 8 is splitting out > 'unlikely' code into 'cold' subfunctions in .text.unlikely. > > I've got some old patches that fix it. Now that GCC 8 is out, I'll need > get the patches dusted off and cleaned up for merging. > > -- > Josh Hello Josh, if you need any additional information, please feel free and contact me. Best regards Damian