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Date: Thu, 17 Feb 2005 10:51:09 +0800 (CST)
From: Tai-hwa Liang <avatar@mmlab.cse.yzu.edu.tw>
To: Greg 'groggy' Lehey <grog@FreeBSD.org>
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cc: Gerald Heinig <gheinig@syskonnect.de>
cc: freebsd-current@freebsd.org
Subject: Re: gdb over Firewire
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On Thu, 17 Feb 2005, Greg 'groggy' Lehey wrote:
> On Thursday, 17 February 2005 at 10:43:44 +0800, Tai-hwa Liang wrote:
>> On Thu, 17 Feb 2005, Greg 'groggy' Lehey wrote:
>>> On Friday, 11 February 2005 at 10:11:31 +0100, Gerald Heinig wrote:
>>>> Hello Current'ers,
>>>>
>>>> I'm trying to get two-machine kernel debugging over Firewire working,
>>>> unfortunately without much luck so far. dconschat over Firewire works
>>>> fine, but gdb won't attach, complaining about get_tty_state failed,
>>>> among other things.
>>>> Is kernel gdb over Firewire a -current-only feature?
>>>
>>>
>>> That's what I get, and it indicates that I don't have gdb capability.
>>> If that's what you get, try building a kernel with firewire support
>>> built-in (as opposed to the (recommended) method of loading the
>>> firewire klds later).  The background here is the hypothesis that the
>>> kernel checks for debug back-ends at boot time, and not later, so if
>>> you load the firewire klds later, it won't be registered.
>>> Note that this is a hypothesis.  If you try this, please let us know
>>> what happens.
>>
>>  From my observation, only "device dcons" is necessary to be static
>> linked in kernel, the rest such like firewire.ko and dcons_crom.ko
>> can still be dynamically loaded.
>
> So you're saying that this approach works for you where it has failed
> otherwise?

   Exactly. It looks like that your hypothesis is right: dcons only
does gdb backend registration during boot time(by static linked approach).