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Message-ID: <AANLkTikn31b=Woy3iMQDaZ54iTa1TK2NcJmGf2+Ou1VP@mail.gmail.com> Date: Wed, 1 Dec 2010 21:58:42 +0800 From: bekars <bekars@...il.com> To: hellogcc@...elists.org Cc: Américo Wang <xiyou.wangcong@...il.com>, linux-kernel@...r.kernel.org, gdb@...rceware.org Subject: Re: [hellogcc] Re: [PATCH] Built kernel without -O2 option 我实验的是 >>> #!/bin/sh >>> gcc "$@" -O0 || >>> gcc "$@" -O1 || >>> gcc "$@" >>> >>> >>>>> then >>>>> >>>>> make CC=./mycc vmlinux 这个方法，感觉简单些，但是编译不过，你的patch我明天试试。 我要调试网络系统，于是修改了net/Makefile，加上KBUILD_CFLAGS += -O0，编译之后能启动内核，但是一有网络通信就panic了，内核顶层的Makefile我用的是-O1优化选项 请问是不是一部分用-O0，一部分用-O2或-O1，编译出来的内核会不稳定？ 在 2010年12月1日 下午9:24，Hui Zhu <teawater@...il.com> 写道： > 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 <bekars@...il.com>: >> 这个好像不行，我在2.6.35.4内核上编译，报错： >> >> ./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 >> >> >> >> 在 2010年11月29日 下午5:45，乔崇 <qiaochong@...ngson.cn> 写道： >>> Hui Zhu 写道: >>>> In this way, you will got a lot of error. >>>> >>>> Hui >>>> >>>> On Mon, Nov 29, 2010 at 16:41, 乔崇 <qiaochong@...ngson.cn> 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, Américo Wang <xiyou.wangcong@...il.com> >>>>> 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 = <value optimized out> >>>>> 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 >>>>> >>>>> >>>>> >>>>> >>>>> -- >>>>> >>>>> 乔崇 qiaochong@...ngson.cn >>>>> >>>>> 2010年 11月 29日 星期一 16:35:38 CST >>>>> >>>> >>>> >>>> >>> >>> >>> -- >>> >>> 乔崇 qiaochong@...ngson.cn >>> 龙芯中科技术服务中心有限公司 >>> office:010-62600855-615 >>> mobile:13521990614 >>> >>> 2010年 11月 29日 星期一 17:38:14 CST >>> >>> >> >> > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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