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Re: memory protection in linux kernels

Cross-posted to 2 groups.

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"Mark" <mark_cruzNOTFORSPAM@hotmail.com> writes:
>
>"Scott Lurndal" <scott@slp53.sl.home> wrote in message 
>news:R2Wfs.9$726.7@fed11.iad...
>>>> Turn on CONFIG_KDB and use kdb to set a watchpoint on the location being
>>>> corrupted.   The processor will automatically stop and drop into kdb
>>>> when the location is modified.
>>>>
>
>[skip]
>>>Thank you. The target is ARM-based and runs the kernel 2.6.31.8, which has
>>>only KGDB support, i.e. as I understand it allows to debug via rs232. What
>>>is the difference with KDB?
>>
>> KDB is built in; it doesn't require a client on another machine like KGDB;
>> but kgdb should work for your case since you've an earlier kernel.
>>
>
>After googling and reading I've set up kgdb over serial line, I can break 
>into the debugger (by stopping the kernel via /proc/sysrq-trigger) and 
>connect from host gdb, which is part of ARM toolchain.
>
>Basically I have development board running embedded linux abd the driver I'm 
>debugging, and my PC with two connections to the board - serial and ethernet 
>(telnet session).
>
>After I connect with host gdb to the target, I'm no longer able to do telnet 
>to the board, because the only way to reproduce the memory corruption is to 
>apply some configuration with user application on the board.
>
>Is it expected or I'm doing something wrong, and there's a way to have alive 
>IP connection to the target *and* GDB session?
>

That's where you need kdb, instead of kgdb.   With kdb, the serial port is
shared between the debugger and the host OS.   The 3.5+ kernels have it built-in,
if I recall correctly.

I've never used kdgb, so I don't know if there is a way to multiplex the console
over the serial port along with the GDB protocol.

scott

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memory protection in linux kernels "Mark" <mark_cruzNOTFORSPAM@hotmail.com> - 2012-10-17 17:32 -0400
  Re: memory protection in linux kernels scott@slp53.sl.home (Scott Lurndal) - 2012-10-18 13:53 +0000
    Re: memory protection in linux kernels "Mark" <mark_cruzNOTFORSPAM@hotmail.com> - 2012-10-18 11:57 -0400
      Re: memory protection in linux kernels scott@slp53.sl.home (Scott Lurndal) - 2012-10-18 16:24 +0000
        Re: memory protection in linux kernels "Mark" <mark_cruzNOTFORSPAM@hotmail.com> - 2012-10-19 18:08 -0400
          Re: memory protection in linux kernels Ian Collins <ian-news@hotmail.com> - 2012-10-20 12:29 +1300
          Re: memory protection in linux kernels scott@slp53.sl.home (Scott Lurndal) - 2012-10-20 19:49 +0000
      Re: memory protection in linux kernels Rainer Weikusat <rweikusat@mssgmbh.com> - 2012-10-18 17:56 +0100

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