Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754896Ab0LAMXM (ORCPT ); Wed, 1 Dec 2010 07:23:12 -0500 Received: from mail-qw0-f46.google.com ([209.85.216.46]:54481 "EHLO mail-qw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751464Ab0LAMXL convert rfc822-to-8bit (ORCPT ); Wed, 1 Dec 2010 07:23:11 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; b=dYqfBhUjhSWzhLRWMM9Sq2FHNLxM6J5eJKVUPLwcxSyIMYX1wL9kQ9ljOUxC4PyKcC 1gWRjRADB/mA7rH45c3KpCYNLtbwMqcOY5jn7mpq9SUiMM1a8MStdiBvGrAEADiqt27f 6bAmULQHYk3l/65tf6tsMaF8iBDaFzfwhGVuY= MIME-Version: 1.0 In-Reply-To: <4CF3762B.9010102@loongson.cn> References: <20101129081619.GD5218@cr0.nay.redhat.com> <4CF36741.9000808@loongson.cn> <4CF3762B.9010102@loongson.cn> Date: Wed, 1 Dec 2010 20:23:10 +0800 Message-ID: Subject: Re: [hellogcc] Re: [PATCH] Built kernel without -O2 option From: bekars To: hellogcc@freelists.org Cc: =?ISO-8859-1?Q?Am=E9rico_Wang?= , linux-kernel@vger.kernel.org, gdb@sourceware.org Content-Type: text/plain; charset=GB2312 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4328 Lines: 151 ???????????РЈ?????2.6.35.4?Ъє??П±??лЈ¬???нЈє ./mm.sh -Wp,-MD,arch/x86/kernel/.entry_32.o.d -nostdinc -isystem /usr/lib/gcc/i486-linux-gnu/4.3.2/include -I/home/baiyu/Melon/RSW3/base_system/linux.DEV/LKGDB/arch/x86/include -Iinclude -include include/generated/autoconf.h -D__KERNEL__ -D__ASSEMBLY__ -m32 -DCONFIG_AS_CFI=1 -DCONFIG_AS_CFI_SIGNAL_FRAME=1 -DCONFIG_AS_CFI_SECTIONS=1 -gdwarf-2 -c -o arch/x86/kernel/entry_32.o arch/x86/kernel/entry_32.S /home/baiyu/Melon/RSW3/base_system/linux.DEV/LKGDB/arch/x86/include/asm/dwarf2.h: Assembler messages: /home/baiyu/Melon/RSW3/base_system/linux.DEV/LKGDB/arch/x86/include/asm/dwarf2.h:46: Error: unknown pseudo-op: `.cfi_sections' /home/baiyu/Melon/RSW3/base_system/linux.DEV/LKGDB/arch/x86/include/asm/dwarf2.h: Assembler messages: /home/baiyu/Melon/RSW3/base_system/linux.DEV/LKGDB/arch/x86/include/asm/dwarf2.h:46: Error: unknown pseudo-op: `.cfi_sections' /home/baiyu/Melon/RSW3/base_system/linux.DEV/LKGDB/arch/x86/include/asm/dwarf2.h: Assembler messages: /home/baiyu/Melon/RSW3/base_system/linux.DEV/LKGDB/arch/x86/include/asm/dwarf2.h:46: Error: unknown pseudo-op: `.cfi_sections' make[2]: *** [arch/x86/kernel/entry_32.o] Error 1 make[1]: *** [arch/x86/kernel] Error 2 make: *** [arch/x86] Error 2 ?? 2010??11??29?? ????5:45???Зі? Рґ???? > Hui Zhu Рґ??: >> In this way, you will got a lot of error. >> >> Hui >> >> On Mon, Nov 29, 2010 at 16:41, ?Зі? wrote: >> >>> does not need change kernel,just write a shell mycc as bellow: >>> >>> #!/bin/sh >>> gcc "$@" -O0 >>> >>> > change mycc to this will work,:) > > #!/bin/sh > gcc "$@" -O0 || > gcc "$@" -O1 || > gcc "$@" > > >>> then >>> >>> make CC=./mycc vmlinux >>> >>> Hui Zhu said >>> >>> On Mon, Nov 29, 2010 at 16:16, Am??rico Wang >>> wrote: >>> >>> >>> On Mon, Nov 29, 2010 at 11:56:15AM +0800, Hui Zhu wrote: >>> >>> >>> Hi, >>> >>> Now, there are a lot of ways to debug the Linux kernel with GDB, like >>> qemu, kgtp or kgdb and so on. >>> But the developer more like add a printk. It have a lot of reason, a big one >>> is: >>> (gdb) p ret >>> $3 = >>> And the code execution order is not right. >>> >>> This is becuase the Kernel is bult with gcc -O2. Gcc will not >>> generate enough debug message with file with -O2. >>> So GDB cannot work very well with Linux kernel. >>> >>> So I make a patch that add a option in "Kernel hacking" called "Close >>> GCC optimization". It will make kernel be built without -O2. >>> >>> I built and use it in i386 and x86_64. I will try to make it OK in other >>> arch. >>> >>> >>> >>> The problem is that some functions _have to_ be inlined and gcc without -O2 >>> doesn't inline them. Have check all the cases? I doubt. >>> >>> >>> If they really need O2, I set them to O2. >>> Actually, this is the main work, find out the file that need the O2. :) >>> >>> For example: >>> ifdef CONFIG_CC_CLOSE_OPTIMIZATION >>> CFLAGS_fpu.o += -O2 >>> CFLAGS_aesni-intel_glue.o += -O2 >>> CFLAGS_ghash-clmulni-intel_glue.o += -O2 >>> endif >>> >>> And I will try to find more of these type files. >>> >>> >>> >>> Also, what is size of vmlinux before applying your patch and after that? >>> Does it increase too much? >>> >>> >>> >>> Before the patch: >>> ls -alh vmlinuz-2.6.37-rc3+ >>> -rw-r--r-- 1 root root 4.1M 2010-11-25 12:02 vmlinuz-2.6.37-rc3+ >>> ls -alh b26no/vmlinux >>> -rwxr-xr-x 1 teawater teawater 135M 2010-11-25 13:31 b26no/vmlinux >>> >>> After the patch: >>> ls -alh vmlinuz-2.6.37-rc3debug+ >>> -rw-r--r-- 1 root root 4.6M 2010-11-25 14:02 vmlinuz-2.6.37-rc3debug+ >>> ls -alh b26/vmlinux >>> -rwxr-xr-x 1 teawater teawater 140M 2010-11-25 11:14 b26/vmlinux >>> >>> Thanks, >>> Hui >>> >>> >>> >>> >>> -- >>> >>> ?Зі? qiaochong@loongson.cn >>> >>> 2010?? 11?? 29?? ????Т» 16:35:38 CST >>> >> >> >> > > > -- > > ?Зі? qiaochong@loongson.cn > ??Рѕ?РїЖј??????????????Ю№?Лѕ > office:010-62600855-615 > mobile:13521990614 > > 2010?? 11?? 29?? ????Т» 17:38:14 CST > > -- 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/