Date: Thu, 17 Feb 2005 10:43:44 +0800 (CST) From: Tai-hwa Liang <avatar@mmlab.cse.yzu.edu.tw> To: Greg 'groggy' Lehey <grog@FreeBSD.org> Cc: freebsd-current@freebsd.org Subject: Re: gdb over Firewire Message-ID: <050217104048D.63322@www.mmlab.cse.yzu.edu.tw> In-Reply-To: <20050217000129.GD69640@wantadilla.lemis.com> References: <420C76C3.202@syskonnect.de> <20050217000129.GD69640@wantadilla.lemis.com>
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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? > > Sorry for the slow reply; I've been busy. > > No, it's not a current-only feature. It used to work, but I've had a > lot of difficulty since the introduction of the new gdb framework. > > Try this: > > $ sysctl debug.kdb > debug.kdb.available: ddb > debug.kdb.current: ddb > debug.kdb.enter: 0 > debug.kdb.stop_cpus: 1 > > 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.
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