From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753348AbcBOOX1 (ORCPT ); Mon, 15 Feb 2016 09:23:27 -0500 Received: from e06smtp13.uk.ibm.com ([195.75.94.109]:42668 "EHLO e06smtp13.uk.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751714AbcBOOXZ (ORCPT ); Mon, 15 Feb 2016 09:23:25 -0500 X-IBM-Helo: d06dlp02.portsmouth.uk.ibm.com X-IBM-MailFrom: oberpar@linux.vnet.ibm.com X-IBM-RcptTo: linux-kbuild@vger.kernel.org;linux-kernel@vger.kernel.org Subject: Re: [PATCH 3/5] gcov: disable for COMPILE_TEST To: Arnd Bergmann , Michal Marek References: <1455293187-179811-1-git-send-email-arnd@arndb.de> <1455293187-179811-4-git-send-email-arnd@arndb.de> Cc: linux-arm-kernel@lists.infradead.org, linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org From: Peter Oberparleiter Message-ID: <56C1DF57.50601@linux.vnet.ibm.com> Date: Mon, 15 Feb 2016 15:23:19 +0100 MIME-Version: 1.0 In-Reply-To: <1455293187-179811-4-git-send-email-arnd@arndb.de> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 16021514-0013-0000-0000-000008A3B551 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12.02.2016 17:06, Arnd Bergmann wrote: > Enabling gcov is counterproductive to compile testing: it significantly > increases the kernel image size, compile time, and it produces lots > of false positive "may be used uninitialized" warnings as the result > of missed optimizations. > > This is in line with how UBSAN_SANITIZE_ALL and PROFILE_ALL_BRANCHES > work, both of which have similar problems. > > With an ARM allmodconfig kernel, I see the build time drop from > 283 minutes CPU time to 225 minutes, and the vmlinux size drops > from 43MB to 26MB. > > Signed-off-by: Arnd Bergmann Agreed that COMPILE_TEST + GCOV_PROFILE_ALL is a very exotic combination with little added use. Acked-by: Peter Oberparleiter > --- > kernel/gcov/Kconfig | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/kernel/gcov/Kconfig b/kernel/gcov/Kconfig > index c92e44855ddd..1276aabaab55 100644 > --- a/kernel/gcov/Kconfig > +++ b/kernel/gcov/Kconfig > @@ -37,6 +37,7 @@ config ARCH_HAS_GCOV_PROFILE_ALL > > config GCOV_PROFILE_ALL > bool "Profile entire Kernel" > + depends on !COMPILE_TEST > depends on GCOV_KERNEL > depends on ARCH_HAS_GCOV_PROFILE_ALL > default n > -- Peter Oberparleiter Linux on z Systems Development - IBM Germany