Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936926Ab3DJJYu (ORCPT ); Wed, 10 Apr 2013 05:24:50 -0400 Received: from jacques.telenet-ops.be ([195.130.132.50]:48712 "EHLO jacques.telenet-ops.be" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934872Ab3DJJYs (ORCPT ); Wed, 10 Apr 2013 05:24:48 -0400 From: Geert Uytterhoeven To: linux-m68k@vger.kernel.org, linux-arch@vger.kernel.org, linux-kbuild@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Geert Uytterhoeven Subject: [PATCH/RFC] m68k: Add -ffreestanding to KBUILD_CFLAGS Date: Wed, 10 Apr 2013 11:24:39 +0200 Message-Id: <1365585879-5321-1-git-send-email-geert@linux-m68k.org> X-Mailer: git-send-email 1.7.0.4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2519 Lines: 71 Without -ffreestanding, gcc may replace calls to standard C library functions by calls to other standard C library functions and/or inline code. This may cause link errors if the replacement code calls a standard C library function that's implemented as a macro in the kernel. E.g. gcc turned strncat(name, "%d", 2); into a call to strlen() and a 16-bit store, causing a link failure, as arch/m68k/include/asm/string.h provides strlen() using a macro: ERROR: "strlen" [net/ipv4/ip_tunnel.ko] undefined! In addition, this saves ca. 64 bytes of text on a typical kernel build. Signed-off-by: Geert Uytterhoeven --- http://kisskb.ellerman.id.au/kisskb/buildresult/8462108/ QUESTION: Should we re-enable -ffreestanding in the main Makefile instead? It was removed in commit 6edfba1b33c701108717f4e036320fc39abe1912 Author: Andi Kleen Date: Sat Mar 25 16:29:49 2006 +0100 [PATCH] x86_64: Don't define string functions to builtin gcc should handle this anyways, and it causes problems when sprintf is turned into strcpy by gcc behind our backs and the C fallback version of strcpy is actually defining __builtin_strcpy Then drop -ffreestanding from the main Makefile because it isn't needed anymore and implies -fno-builtin, which is wrong now. (it was only added for x86-64, so dropping it should be safe) Noticed by Roman Zippel Cc: Roman Zippel Signed-off-by: Andi Kleen Signed-off-by: Linus Torvalds Subsequently, it got re-enabled for mips, sh, x86-32, um/x86, xtensa, and score. arch/m68k/Makefile | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/arch/m68k/Makefile b/arch/m68k/Makefile index 2f02acf..8e06a38 100644 --- a/arch/m68k/Makefile +++ b/arch/m68k/Makefile @@ -58,7 +58,7 @@ cpuflags-$(CONFIG_M5206e) := $(call cc-option,-mcpu=5206e,-m5200) cpuflags-$(CONFIG_M5206) := $(call cc-option,-mcpu=5206,-m5200) KBUILD_AFLAGS += $(cpuflags-y) -KBUILD_CFLAGS += $(cpuflags-y) -pipe +KBUILD_CFLAGS += $(cpuflags-y) -pipe -ffreestanding ifdef CONFIG_MMU # without -fno-strength-reduce the 53c7xx.c driver fails ;-( KBUILD_CFLAGS += -fno-strength-reduce -ffixed-a2 -- 1.7.0.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/