/home/sources/linux-2.6.29/init/main.c:694: undefined reference to `__gnu_mcount_nc'
init/built-in.o: In function `init_post':
/home/sources/linux-2.6.29/init/main.c:790: undefined reference to `__gnu_mcount_nc'
init/built-in.o: In function `name_to_dev_t':
/home/sources/linux-2.6.29/init/do_mounts.c:77: undefined reference to `__gnu_mcount_nc'
init/built-in.o: In function `rest_init':
/home/sources/linux-2.6.29/init/main.c:452: undefined reference to `__gnu_mcount_nc'
init/built-in.o: In function `calibrate_delay':
/home/sources/linux-2.6.29/init/calibrate.c:123: undefined reference to `__gnu_mcount_nc'
arch/arm/kernel/built-in.o:/home/sources/linux-2.6.29/arch/arm/kernel/elf.c:8: more undefined references to `__gnu_mcount_nc' follow
make: *** [.tmp_vmlinux1] Error 1
解决方法：
需要补丁__gnu_mcount_nc_patch.patch.gz
下载之后放在Linux内核根目录下，如我的是：/home/liuhui8989/Information/linux-2.6.31
从终端下进入根目录/home/liuhui8989/Information/linux-2.6.31下执行以下操作：
gunzip -dc __gnu_mcount_nc_patch.patch.gz |patch -p1
(注意：“__”为两个下划线连在一起，“p1”后面的是阿拉伯数字1，还要注意空格）
打印出以下信息即表示成功：
root@ubuntu:/home/liuhui8989/Information/linux-2.6.31# gunzip -dc __gnu_mcount_nc_patch.patch.gz |patch -p1
patching file arch/arm/include/asm/ftrace.h
patching file arch/arm/kernel/armksyms.c
patching file arch/arm/kernel/entry-common.S