From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 6317 invoked by alias); 1 Dec 2010 13:24:55 -0000 Received: (qmail 6304 invoked by uid 22791); 1 Dec 2010 13:24:54 -0000 X-SWARE-Spam-Status: No, hits=0.7 required=5.0 tests=AWL,BAYES_50,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FROM,MIME_CHARSET_FARAWAY,RCVD_IN_DNSWL_LOW,TW_CL,TW_GD,TW_KG,TW_RW,TW_WX,T_FRT_BELOW2,T_TO_NO_BRKTS_FREEMAIL X-Spam-Check-By: sourceware.org Received: from mail-wy0-f169.google.com (HELO mail-wy0-f169.google.com) (74.125.82.169) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Wed, 01 Dec 2010 13:24:48 +0000 Received: by wyb42 with SMTP id 42so15083133wyb.0 for ; Wed, 01 Dec 2010 05:24:45 -0800 (PST) Received: by 10.216.18.71 with SMTP id k49mr7555643wek.67.1291209885819; Wed, 01 Dec 2010 05:24:45 -0800 (PST) MIME-Version: 1.0 Received: by 10.216.186.148 with HTTP; Wed, 1 Dec 2010 05:24:25 -0800 (PST) In-Reply-To: References: <20101129081619.GD5218@cr0.nay.redhat.com> <4CF36741.9000808@loongson.cn> <4CF3762B.9010102@loongson.cn> From: Hui Zhu Date: Wed, 01 Dec 2010 13:24:00 -0000 Message-ID: Subject: Re: [hellogcc] Re: [PATCH] Built kernel without -O2 option 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: quoted-printable X-IsSubscribed: yes Mailing-List: contact gdb-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-owner@sourceware.org X-SW-Source: 2010-12/txt/msg00008.txt.bz2 2.6.35.4 is a little old. What I try is 2.6.37-rc3+ and 2.6.37-rc4+ amd64 and i386. Thanks, Hui 2010/12/1 bekars : > =D5=E2=B8=F6=BA=C3=CF=F1=B2=BB=D0=D0=A3=AC=CE=D2=D4=DA2.6.35.4=C4=DA=BA= =CB=C9=CF=B1=E0=D2=EB=A3=AC=B1=A8=B4=ED=A3=BA > > ./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=3D1 -DCONFIG_AS_CFI_SIGNAL_FRAME=3D1 > -DCONFIG_AS_CFI_SECTIONS=3D1 -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/d= warf2.h: > Assembler messages: > /home/baiyu/Melon/RSW3/base_system/linux.DEV/LKGDB/arch/x86/include/asm/d= warf2.h:46: > Error: unknown pseudo-op: `.cfi_sections' > /home/baiyu/Melon/RSW3/base_system/linux.DEV/LKGDB/arch/x86/include/asm/d= warf2.h: > Assembler messages: > /home/baiyu/Melon/RSW3/base_system/linux.DEV/LKGDB/arch/x86/include/asm/d= warf2.h:46: > Error: unknown pseudo-op: `.cfi_sections' > /home/baiyu/Melon/RSW3/base_system/linux.DEV/LKGDB/arch/x86/include/asm/d= warf2.h: > Assembler messages: > /home/baiyu/Melon/RSW3/base_system/linux.DEV/LKGDB/arch/x86/include/asm/d= warf2.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 > > > > =D4=DA 2010=C4=EA11=D4=C229=C8=D5 =CF=C2=CE=E75:45=A3=AC=C7=C7=B3=E7 =D0=B4=B5=C0=A3=BA >> Hui Zhu =D0=B4=B5=C0: >>> In this way, you will got a lot of error. >>> >>> Hui >>> >>> On Mon, Nov 29, 2010 at 16:41, =C7=C7=B3=E7 wro= te: >>> >>>> 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=3D./mycc vmlinux >>>> >>>> Hui Zhu said >>>> >>>> On Mon, Nov 29, 2010 at 16:16, Am=A8=A6rico 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 b= ig one >>>> is: >>>> (gdb) p ret >>>> $3 =3D >>>> 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 ot= her >>>> arch. >>>> >>>> >>>> >>>> The problem is that some functions _have to_ be inlined and gcc withou= t -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 +=3D -O2 >>>> CFLAGS_aesni-intel_glue.o +=3D -O2 >>>> CFLAGS_ghash-clmulni-intel_glue.o +=3D -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 tha= t? >>>> 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 >>>> >>>> >>>> >>>> >>>> -- >>>> >>>> =C7=C7=B3=E7 qiaochong@loongson.cn >>>> >>>> 2010=C4=EA 11=D4=C2 29=C8=D5 =D0=C7=C6=DA=D2=BB 16:35:38 CST >>>> >>> >>> >>> >> >> >> -- >> >> =C7=C7=B3=E7 qiaochong@loongson.cn >> =C1=FA=D0=BE=D6=D0=BF=C6=BC=BC=CA=F5=B7=FE=CE=F1=D6=D0=D0=C4=D3=D0=CF=DE= =B9=AB=CB=BE >> office:010-62600855-615 >> mobile:13521990614 >> >> 2010=C4=EA 11=D4=C2 29=C8=D5 =D0=C7=C6=DA=D2=BB 17:38:14 CST >> >> > >