kgdb debugging

[alan yang]

thank you all, device.hints solved it!

On Tue, Oct 7, 2008 at 11:14 AM, Julian Elischer <julian at elischer.org> wrote:
> alan yang wrote:
>>
>> Could people shed some light how to get remote debugging going, must
>> be something that i overlooked, really appreciate.
>>
>> Two FreeBSD7 systems, target and development, connected with null
>> modem cable on each's COM1.
>>
>> step 1)
>>        -  rebuild kernel with following options:
>>                options         DDB
>>                options         KDB
>>                options         GDB
>>
>>                makeoptions     DEBUG=-g
>
> add hints.dev.uart.0.flags=0xc0
> (or whatever it is) (see man uart or man sio)
> to /boot/device.hints
>
>>
>> step 2)
>>        -  from development system
>>                cd to /usr/src/sys/i386/comiple/MYKERNEL
>>                kgdb -r /dev/cuad0 kernel.debug
>>
>>                it displays the following:
>>                Switching to remote protocol
>>                Ignoring packet error, continuing
>>                        .........
>>                Couldn't establish connection to remote target
>>                Malformed response to offset query, timeout
>>
>> step 3)
>>        -  from targetsystem:
>>                1.  Ctrl + Alt + Esc to go into db
>>                2.  from db> type gdb
>>                3.  it displays: "The remote GDB backend could not be
>> selected"
>>
>>
>>
>> On Mon, Oct 6, 2008 at 5:12 PM, alan yang <alancyang at gmail.com> wrote:
>>>
>>> the problem is, when entering gdb from db as described in the following:
>>> --
>>> Enter ing gdb from ddb
>>> In FreeBSD you can build a kernel with support for both ddb and gdb.
>>> You can then
>>> change backwards and forwards between them. For example, if you're in
>>> ddb, you can
>>> go to gdb like this:
>>> db> gdb
>>> Next trap will enter GDB remote protocol mode
>>> db> si step a single instruction to reenter ddb
>>> --
>>> after typing gdb command, it says: "The remote GDB backend could not
>>> be selected"
>>> that i am not sure what this indicates; looking at subr_kdb.c, wonder
>>> maybe kdb_dbbe_set is not set?  seems kdb_dbbe_set is not referenced
>>> anywhere, not sure how to get it right.
>>>
>>> thanks for shed some light ...
>>>
>>> On Mon, Oct 6, 2008 at 4:26 PM, Pietro Cerutti <gahr at freebsd.org> wrote:
>>>>
>>>> -----BEGIN PGP SIGNED MESSAGE-----
>>>> Hash: SHA512
>>>>
>>>> alan yang wrote:
>>>> | hi, there,
>>>> |
>>>> | wonder people can shed some lights on remote debugging.  i have
>>>> | freebsd7 configured with option DDB / KDB / GDB but after entering the
>>>> | db on the target system the command gdb gives "the remote GDB backend
>>>> | could not be selected".
>>>> |
>>>> | i browsed through the mailing list, and do find 1 similar post but
>>>> | without answer.
>>>> |
>>>> | thanks in advance & apology if i overlooked things ...
>>>>
>>>> I suggest the following tutorial:
>>>> http://www.lemis.com/grog/Papers/Debug-tutorial/tutorial.pdf
>>>>
>>>> Have fun :)
>>>>
>>>> |
>>>> | cheers,
>>>> | alan
>>>> | _______________________________________________
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>>>>
>>>>
>>>> - --
>>>> Pietro Cerutti
>>>> gahr at FreeBSD.org
>>>>
>>>> PGP Public Key:
>>>> http://gahr.ch/pgp
>>>>
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>>>> Version: GnuPG v2.0.9 (FreeBSD)
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