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Message-ID: <AANLkTinW6Yp8W4x7DxVCY-AttMMWhkxFKXbmqK9fzpVD@mail.gmail.com> Date: Wed, 1 Dec 2010 23:01:56 +0800 From: Hui Zhu <teawater@...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 2010/12/1 bekars <bekars@...il.com>: > 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？ > > I think is because some function without -O2 will need a lot of stack (I got some warning about it when I built). Call this function will make kernel stack overflow. So I add some function to -O2 and increase the stack size of amd64. +#ifdef CONFIG_CC_CLOSE_OPTIMIZATION +#define THREAD_ORDER 2 +#else #define THREAD_ORDER 1 +#endif #define THREAD_SIZE (PAGE_SIZE << THREAD_ORDER) #define CURRENT_MASK (~(THREAD_SIZE - 1)) Thanks, Hui > 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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