Date: Mon, 25 Feb 2008 15:44:28 +0200 From: "Yehonatan Yossef" <yoniy@mellanox.co.il> To: "Mel" <fbsd.questions@rachie.is-a-geek.net>, <freebsd-questions@freebsd.org> Subject: RE: Capturing dmesg upon system crash on 6.3 Message-ID: <6C2C79E72C305246B504CBA17B5500C90364164C@mtlexch01.mtl.com> In-Reply-To: <200802251436.32206.fbsd.questions@rachie.is-a-geek.net>
next in thread | previous in thread | raw e-mail | index | archive | help
> On Monday 25 February 2008 13:32:01 Yehonatan Yossef wrote: > > > > I'm facing a system reboot upon loading of the driver, and > > > > > > I could use > > > > > > > a tool for capturing dmesg upon system crash (such as=20 > netconsole=20 > > > > on Linux). > > > > > > Your kernel isn't setup for driver development: > > > http://www.freebsd.org/doc/en_US.ISO8859-1/books/developers-ha > > > ndbook/kerneldebug.html > > > http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/kern > > > elconfig.html > > > > > > Basically, your system is rebooting cause the kernel panics and=20 > > > you're not setup for crash dumps, or anything that could help you=20 > > > diagnose the panic. > > > -- > > > Mel > > > > I've setup the dumpdev/dumpdir and I get a vmcore image=20 > upon a crash. > > > > I don't really understand how to use kgdb in order to read=20 > it but more=20 > > than that - I don't need that much of data. I only want the dmesg=20 > > report at the moment, see at what point my driver went=20 > crazy. Is it possible? >=20 >=20 > Uhm, no. Fundamental logic flaw: when a kernel is stopped,=20 > you can't issue userland commands. All you have when you use=20 > ddb, is the contents of the registers, ram and backtrace. >=20 > You really want ddb in the kernel: when a kernel panics,=20 > it'll drop to ddb and you can examine registers and do a=20 > backtrace, instead of dumping core and rebooting. It should=20 > point exactly to where your driver went crazy. > -- > Mel >=20 I meant making the dmesg log sent over the network/serial console to a linux machine. I just found out about syslogd, I'm trying to figure out how to use it. DDB sounds like a great option for deeper debugging, I'll use it. Yony
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?6C2C79E72C305246B504CBA17B5500C90364164C>