Hello,

Thanks to your clues, I have found where the problem came from, it was the kernel option CONFIG_DEBUG_RODATA, which set write protection on some read-only kernel pages.

Obviously, KDB cannot insert its trapping instruction.

Best regards,
Loic


Mulyadi Santosa a écrit :
On Sat, Sep 19, 2009 at 6:58 PM, Loic Pefferkorn
<[email protected]> wrote:
Hello,

I'm trying to put a breakpoint on do_sys_open function through Kdb on a
linux-2.6.30 with the command:

kdb> bp do_sys_open

But I get the following error:

Invalid address for breakpoint, ignoring bp command
diag: -21: Invalid address
kdb>

However I'm able to disassemble this function using id command, which means
do_sys_open symbol is known to kdb.

Does someone has an idea about this error ?

Thanks in advance
Loic

Not a very specific idea. The fact that you can dissasemble
do_sys_open means the symbol is resolvable. Thus I suspect it is
either a bug in KDB  or KDB is unable to put a breakpoint in that
respective address since the instruction(s) in that address is still
actively executed, thus it can not be replaced with trapping
instruction ( INT 3 right? or something like that)



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