From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756045AbZBXGvX (ORCPT ); Tue, 24 Feb 2009 01:51:23 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753900AbZBXGvO (ORCPT ); Tue, 24 Feb 2009 01:51:14 -0500 Received: from bombadil.infradead.org ([18.85.46.34]:54726 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753883AbZBXGvO (ORCPT ); Tue, 24 Feb 2009 01:51:14 -0500 Date: Tue, 24 Feb 2009 01:51:12 -0500 From: Kyle McMartin To: linuxppc-dev@ozlabs.org Cc: linux-kernel@vger.kernel.org, kyle@redhat.com, roland@redhat.com, aoliva@redhat.com Subject: [PATCH/RFC] powerpc: avoid generating .eh_frame sections with gcc-4.4 Message-ID: <20090224065112.GA6690@bombadil.infradead.org> Reply-To: kyle@infradead.org MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline 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 From: Kyle McMartin On ppc64 (at least) gcc-4.4 is defaulting to generating .eh_frame sections, which are, for the kernel, fairly pointless. Additionally, on ppc64 this generates a relocation format which the kernel module loader does not currently support (R_PPC64_REL32.) Alexandre Oliva verifies that -fno-dwarf2-cfi-asm prevents this .eh_frame section from being generated. These seem to be used for unwinding, but it doesn't look like we currently use them anywhere. (In fact, we explicitly dump them in the x86_64 linker script.) If these .eh_frame sections are eventually used, adding a per-arch CONFIG_WANT_UNWIND check would be trivial. (This was reported against Fedora, which appears to be the only distro doing any building against gcc-4.4 at present: RH bz#486545.) Signed-off-by: Kyle McMartin Cc: roland@redhat.com Cc: aoliva@redhat.com --- diff --git a/Makefile b/Makefile index df6ce3e..d66a512 100644 --- a/Makefile +++ b/Makefile @@ -566,6 +566,11 @@ KBUILD_CFLAGS += $(call cc-option,-Wdeclaration-after-statement,) # disable pointer signed / unsigned warnings in gcc 4.0 KBUILD_CFLAGS += $(call cc-option,-Wno-pointer-sign,) +# gcc-4.4 defaults to generating .eh_frame sections, but we aren't +# interested in those currently. additionally, it causes issues on some +# architectures. +KBUILD_CFLAGS += $(call cc-option,-fno-dwarf2-cfi-asm) + # Add user supplied CPPFLAGS, AFLAGS and CFLAGS as the last assignments # But warn user when we do so warn-assign = \