使用带有/proc/kcore 的 gdb 时，为什么我的 vmlinux 中没有调试符号? [英] Why are there no debug symbols in my vmlinux when using gdb with /proc/kcore?

问题描述

我已经为 y 配置了所有与 CONFIG_DEBUG_ 相关的选项，但是当我尝试调试内核时，它说没有找到调试符号:

I've configure all CONFIG_DEBUG_ related options to y,but when I try to debug the kernel,it says no debug symbols found:

gdb /usr/src/linux-2.6.32.9/vmlinux /proc/kcore

Reading symbols from /usr/src/linux-2.6.32.9/vmlinux...(no debugging symbols found)...done.

为什么?

推荐答案

这是我目前最好的猜测:我不知道，没关系.

Here is my best guess so far: I don't know, and it doesn't matter.

我不知道为什么 GDB 会打印消息(未找到调试符号)".在构建自己的内核时，我实际上已经看到了这一点.我将内核配置为使用调试符号，但 GDB 在查看内核映像时仍会打印此消息.我从不费心去研究它，因为我的图像仍然可以很好地调试.尽管有消息，GDB 仍然可以反汇编函数、添加断点、查找符号和单步执行函数.我从来没有注意到缺少调试功能.我猜同样的事情也发生在你身上.

I don't know why GDB is printing the message "(no debugging symbols found)". I've actually seen this when building my own kernels. I configure a kernel to use debug symbols, but GDB still prints this message when it looks at the kernel image. I never bothered to look into it, because my image can still be debugged fine. Despite the message, GDB can still disassemble functions, add breakpoints, look up symbols, and single-step through functions. I never noticed a lack of debugging functionality. I'm guessing that the same thing is happening to you.

根据您对问题的评论，您似乎在使用调试器搜索错误的符号.系统调用处理程序以 sys_ 前缀开头，但您无法通过查看代码来判断.宏 SYSCALL_DEFINE4(ptrace, ...) 只是最终将函数声明为 asmlinkage long sys_ptrace(...)，尽管如果你有它会做一些其他疯狂的事情ftrace 已启用.

Based on the your comments to the question, it looks like you were searching for the wrong symbol with your debugger. System call handlers start with a prefix of sys_, but you can't tell from looking at the code. The macro SYSCALL_DEFINE4(ptrace, ...) just ends up declaring the function as asmlinkage long sys_ptrace(...), although it does some other crazy stuff if you have ftrace enabled.

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