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I want to debug a kernel module with kgdb,do as the following:

gdb: add-symbol-file /home/gaoqiang/kernel-32/fs/ext4/ext4.ko 0xffffffffa0122000 -s .bss 0xffffffffa016b380 -s .data 0xffffffffa0168400

gdb: break ext4_getattr gdb: c

I successfully get to the break point,but gdb told me :"[ No Source Available ]" then how to get gdb to find source code for the module?

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  • Is it a kernel you have built or a kernel provided by your Linux distro? For the latter, the debug info GDB needs can actually be in a separate file rather than in ext4.ko itself. You can look for the packages like kernel-*-debug, kernel-*-debuginfo, etc., in the repositories of your distro. Commented Dec 28, 2012 at 7:24
  • BTW, could you describe a bit what you are trying to find out about ext4 with kgdb? In some cases, there could be easier ways to collect the data you need than using a debugger. Commented Dec 28, 2012 at 7:27

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As per your problem

(gdb) add-symbol-file /home/gaoqiang/kernel-32/fs/ext4/ext4.ko 0xffffffffa0122000 -s .bss 0xffffffffa016b380 -s .data 0xffffffffa0168400

I assume that the module is present in the directory /home/gaoqiang/kernel-32/fs/ext4/. If your source code is also in directory the gdb would not have given the error/warning.

So if the source files for ext4.ko module say ext4.c and the rest are not present in that directory, copy them to the directory.

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 (gdb)set solib-search-path /home/gaoqiang/kernel-32/fs/ext4/
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