Jason,

Jason Wessel <[email protected]> writes:

> Derek Atkins wrote:
>> Jason,
>>
>> Jason Wessel <[email protected]> writes:
>>
>>   
>>> Unless you patch in the kgdb8250 driver, you cannot use it.  If you
>>> build the kernel documentation you would get a directory called
>>> Documentation/DocBook/kgdb.   In there you would find information about
>>> kgdboc, which is the only I/O driver merged to the mainline kernel.
>>>     
>>
>> One of the benefits of the (very old, like pre-2.6.25) kgdb8250 driver
>> was that it would both allow you to ^C from gdb to stop the running
>> kernel (no need to use the SysRq-g) and also it would allow all printk's
>> to be delivered to the remote gdb process.  Last time I tried the kgdboc
>> driver (probably about 2.6.28) it didn't have either of these features.
>> Has that changed more recently?  If so, where and when?
>>
>>   
>
> I have patches to kgdboc which allow you to do this, but Alan Cox (tty
> maintainer at the time) rejected them because the tty lisc and locking
> infrastructure was in complete flux.  The extension to kgdboc allows
> kgdb to open a simulated file handle such that the tty can be opened
> before the user space init or on a tty that has not been opened by
> another program.

Oh, excellent!

Where can I find these specific patches/changes?

> In the later half of 2009 Alan stopped maintaining the tty layer, and
> perhaps these patches might get accepted this time around.  I was
> planning on resubmitting some of this work after the kdb / kgdb merge
> activities are completed.
>
> It may not be of interest, but the kgdboc with this functionality also
> has the capability to declare any key you like as the kernel interrupt
> character.  This was needed on archs like sparc where sysrq can be
> overloaded with an exit to prom code.
>
> Long story short:
>   * The functionality you asked about is not in the mainline
>   * There are patches in the kgdb dev tree for this

* nods *

I'm happy to compile my own kernels... I've been doing it for a while
(I have a kgdb-enabled kernel for CentOS 5.3 and Ubuntu 8.04) so I'm
comfortable patching a vendor kernel.  So it would be nice to get a
pointer to these specific patches!

Thank you in advance!!!

> Jason.

-derek

-- 
       Derek Atkins, SB '93 MIT EE, SM '95 MIT Media Laboratory
       Member, MIT Student Information Processing Board  (SIPB)
       URL: http://web.mit.edu/warlord/    PP-ASEL-IA     N1NWH
       [email protected]                        PGP key available

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