debugging arm executuble with gdb

[csne...@gmail.com]

Hi,

I have compiled linux kernel with arm-eabi toolchain on Ubuntu. The
kernel is working. Now I'd like to debug it with gdb.
I tried this command: arm-eabi-gdb vmlinux

My questions:
Which gdb should I use?
There is a gdb in the arm-eabi (downloaded with android) toolchain. This
will good?
I have tried that but I have got Don't know how to run. Try "help
target" error message.
I tried to set breakpoint to __init_begin, this works but when I tried
to start the debug with *start, run, cont* I have got this error
message.
attila@attila-desktop:~/Upload$ arm-eabi-gdb vmlinux
GNU gdb (GDB) 7.1-android-gg2
This GDB was configured as "--host=x86_64-linux-gnu --target=arm-elf-linux".
Reading symbols from /home/attila/Upload/vmlinux...(no debugging symbols found)...done.
(gdb) break __init_begin
Breakpoint 1 at 0xc0008000
(gdb) load vmlinux
You can't do that when your target is `exec'
(gdb) start
Function "main" not defined.
Make breakpoint pending on future shared library load? (y or [n]) n
Starting program: /home/attila/Upload/vmlinux
Don't know how to run. Try "help target".
(gdb) cont
The program is not being run.
(gdb) run
Starting program: /home/attila/Upload/vmlinux
Don't know how to run. Try "help target".

[Tauno Voipio]

Kernel in not a normal executable. It needs special techniques to debug.
One of them is the kernel debugger, kgdb.

Please google for 'linux kernel debugging'. There are plenty of hits.

--

Tauno Voipio

[texane]

The kernel is not runnable as a classical userland executable
is (that is why you cannot run it from GDB), even if the binary
formats are the same (that is why you can open it in GDB, and
even put a breakpoint on a symbol).

You must debug a running kernel, be it on your target hardware
or an emulator, and use the proposed documentation reference.



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