From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755989AbYGJUnm (ORCPT ); Thu, 10 Jul 2008 16:43:42 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752855AbYGJUne (ORCPT ); Thu, 10 Jul 2008 16:43:34 -0400 Received: from [198.99.130.12] ([198.99.130.12]:56732 "EHLO saraswathi.solana.com" rhost-flags-FAIL-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1751514AbYGJUnd (ORCPT ); Thu, 10 Jul 2008 16:43:33 -0400 Date: Thu, 10 Jul 2008 16:42:48 -0400 From: Jeff Dike To: Sergei Trofimovich Cc: Linux Kernel Mailing List Subject: Re: uml: sparse inlines gcc-4.{2,3} compilation hack Message-ID: <20080710204248.GA21205@c2.user-mode-linux.org> References: <20080710155029.4cf5cb8f@slyfox.slynet.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080710155029.4cf5cb8f@slyfox.slynet.org> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jul 10, 2008 at 03:50:29PM +0300, Sergei Trofimovich wrote: > Small ARCH=um SUBARCH=i386 .config is in attach. > How to fix properly such kind of miscompilation? (gcc-4.3.1) > Now I have to use hacks like this: Use the patch below instead. Jeff -- Work email - jdike at linux dot intel dot com commit 4f81c5350b44bcc501ab6f8a089b16d064b4d2f6 Author: Jeff Dike Date: Mon Jul 7 13:36:56 2008 -0400 [UML] fix gcc ICEs and unresolved externs There are various constraints on the use of unit-at-a-time: - i386 uses no-unit-at-a-time for pre-4.0 (not 4.3) - x86_64 uses unit-at-a-time always Uli reported a crash on x86_64 with gcc 4.1.2 with unit-at-a-time, resulting in commit c0a18111e571138747a98af18b3a2124df56a0d1 Ingo reported a gcc internal error with gcc 4.3 with no-unit-at-a-timem, resulting in 22eecde2f9034764a3fd095eecfa3adfb8ec9a98 Benny Halevy is seeing extern inlines not resolved with gcc 4.3 with no-unit-at-a-time This patch reintroduces unit-at-a-time for gcc >= 4.0, bringing back the possibility of Uli's crash. If that happens, we'll debug it. I started seeing both the internal compiler errors and unresolved inlines on Fedora 9. This patch fixes both problems, without so far reintroducing the crash reported by Uli. Signed-off-by: Jeff Dike Cc: Benny Halevy Cc: Adrian Bunk Cc: Ingo Molnar Cc: Ulrich Drepper Signed-off-by: Linus Torvalds diff --git a/arch/um/Makefile b/arch/um/Makefile index dbeab15..ca40397 100644 --- a/arch/um/Makefile +++ b/arch/um/Makefile @@ -77,7 +77,6 @@ include $(srctree)/$(ARCH_DIR)/Makefile-os-$(OS) KERNEL_DEFINES = $(strip -Derrno=kernel_errno -Dsigprocmask=kernel_sigprocmask \ -Dmktime=kernel_mktime $(ARCH_KERNEL_DEFINES)) KBUILD_CFLAGS += $(KERNEL_DEFINES) -KBUILD_CFLAGS += $(call cc-option,-fno-unit-at-a-time,) PHONY += linux diff --git a/arch/um/Makefile-i386 b/arch/um/Makefile-i386 index 561e373..302cbe5 100644 --- a/arch/um/Makefile-i386 +++ b/arch/um/Makefile-i386 @@ -32,4 +32,11 @@ cflags-y += $(call cc-option,-mpreferred-stack-boundary=2) # an unresolved reference. cflags-y += -ffreestanding +# Disable unit-at-a-time mode on pre-gcc-4.0 compilers, it makes gcc use +# a lot more stack due to the lack of sharing of stacklots. Also, gcc +# 4.3.0 needs -funit-at-a-time for extern inline functions. +KBUILD_CFLAGS += $(shell if [ $(call cc-version) -lt 0400 ] ; then \ + echo $(call cc-option,-fno-unit-at-a-time); \ + else echo $(call cc-option,-funit-at-a-time); fi ;) + KBUILD_CFLAGS += $(cflags-y) diff --git a/arch/um/Makefile-x86_64 b/arch/um/Makefile-x86_64 index 8ed362f..a9cd7e7 100644 --- a/arch/um/Makefile-x86_64 +++ b/arch/um/Makefile-x86_64 @@ -21,3 +21,6 @@ HEADER_ARCH := x86 LINK-$(CONFIG_LD_SCRIPT_DYN) += -Wl,-rpath,/lib64 LINK-y += -m64 + +# Do unit-at-a-time unconditionally on x86_64, following the host +KBUILD_CFLAGS += $(call cc-option,-funit-at-a-time)