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>
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> 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 > netconsole > > > > 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 > > > you're not setup for crash dumps, or anything that could help you > > > diagnose the panic. > > > -- > > > Mel > > > > I've setup the dumpdev/dumpdir and I get a vmcore image > upon a crash. > > > > I don't really understand how to use kgdb in order to read > it but more > > than that - I don't need that much of data. I only want the dmesg > > report at the moment, see at what point my driver went > crazy. Is it possible? > > > Uhm, no. Fundamental logic flaw: when a kernel is stopped, > you can't issue userland commands. All you have when you use > ddb, is the contents of the registers, ram and backtrace. > > You really want ddb in the kernel: when a kernel panics, > it'll drop to ddb and you can examine registers and do a > backtrace, instead of dumping core and rebooting. It should > point exactly to where your driver went crazy. > -- > Mel > 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
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