From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 5824 invoked by alias); 1 Dec 2010 12:23:21 -0000 Received: (qmail 5803 invoked by uid 22791); 1 Dec 2010 12:23:18 -0000 X-SWARE-Spam-Status: No, hits=2.9 required=5.0 tests=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-qy0-f176.google.com (HELO mail-qy0-f176.google.com) (209.85.216.176) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Wed, 01 Dec 2010 12:23:12 +0000 Received: by qyk10 with SMTP id 10so8543850qyk.0 for ; Wed, 01 Dec 2010 04:23:10 -0800 (PST) MIME-Version: 1.0 Received: by 10.224.181.140 with SMTP id by12mr5870868qab.39.1291206190319; Wed, 01 Dec 2010 04:23:10 -0800 (PST) Received: by 10.220.60.10 with HTTP; Wed, 1 Dec 2010 04:23:10 -0800 (PST) In-Reply-To: <4CF3762B.9010102@loongson.cn> References: <20101129081619.GD5218@cr0.nay.redhat.com> <4CF36741.9000808@loongson.cn> <4CF3762B.9010102@loongson.cn> Date: Wed, 01 Dec 2010 12:23:00 -0000 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: quoted-printable 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/msg00004.txt.bz2 =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/dwa= rf2.h: Assembler messages: /home/baiyu/Melon/RSW3/base_system/linux.DEV/LKGDB/arch/x86/include/asm/dwa= rf2.h:46: Error: unknown pseudo-op: `.cfi_sections' /home/baiyu/Melon/RSW3/base_system/linux.DEV/LKGDB/arch/x86/include/asm/dwa= rf2.h: Assembler messages: /home/baiyu/Melon/RSW3/base_system/linux.DEV/LKGDB/arch/x86/include/asm/dwa= rf2.h:46: Error: unknown pseudo-op: `.cfi_sections' /home/baiyu/Melon/RSW3/base_system/linux.DEV/LKGDB/arch/x86/include/asm/dwa= rf2.h: Assembler messages: /home/baiyu/Melon/RSW3/base_system/linux.DEV/LKGDB/arch/x86/include/asm/dwa= rf2.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 wrot= e: >> >>> 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 bi= g 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 oth= er >>> 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 +=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 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 >>> >>> >>> >>> >>> -- >>> >>> =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 > >