Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752347Ab0K2Jp0 (ORCPT ); Mon, 29 Nov 2010 04:45:26 -0500 Received: from webmail.ict.ac.cn ([159.226.39.7]:53184 "EHLO ict.ac.cn" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750998Ab0K2JpZ (ORCPT ); Mon, 29 Nov 2010 04:45:25 -0500 Message-ID: <4CF3762B.9010102@loongson.cn> Date: Mon, 29 Nov 2010 17:45:15 +0800 From: =?GB2312?B?x8ez5w==?= User-Agent: Mozilla-Thunderbird 2.0.0.22 (X11/20090706) MIME-Version: 1.0 To: hellogcc@freelists.org CC: =?GB2312?B?QW2opnJpY28gV2FuZw==?= , linux-kernel@vger.kernel.org, gdb@sourceware.org Subject: Re: [hellogcc] Re: [PATCH] Built kernel without -O2 option References: <20101129081619.GD5218@cr0.nay.redhat.com> <4CF36741.9000808@loongson.cn> In-Reply-To: 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: 2880 Lines: 121 Hui Zhu д??: > In this way, you will got a lot of error. > > Hui > > On Mon, Nov 29, 2010 at 16:41, ?ǳ? 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 >> >> >> >> >> -- >> >> ?ǳ? qiaochong@loongson.cn >> >> 2010?? 11?? 29?? ????һ 16:35:38 CST >> > > > -- ?ǳ? qiaochong@loongson.cn ??о?пƼ??????????????޹?˾ office:010-62600855-615 mobile:13521990614 2010?? 11?? 29?? ????һ 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/