Date: Sun, 4 Feb 1996 03:00:10 +0100 (MET) From: J Wunsch <j@uriah.heep.sax.de> To: freebsd-hackers@freebsd.org (FreeBSD hackers) Subject: Re: How to use DDB to debug a boottime panic? Message-ID: <199602040200.DAA14870@uriah.heep.sax.de> In-Reply-To: <Pine.BSF.3.91.960203173423.219B-100000@ki.net> from "Marc G. Fournier" at Feb 3, 96 05:47:21 pm
next in thread | previous in thread | raw e-mail | index | archive | help
As Marc G. Fournier wrote: > Okay, I delved into DDB, and came out unscathed, I think...well, at least > I seem to have more info and knowledge then I started, which is a good > thing :) :) > Using sd(0,a)/kernel -d to get into DDB (several times), I performed the > following: > > b ncr_attach + 0x192 (according to handbook, this should work) > - From Handbook: > - Simple expressions are allowed, for example: function-name + 0x103. > - When I tried, it always ran through until it hit the panic *shrug* It works for me, though i'm not sure about the early boot stages. I think interrupts are still disabled there, and yup, i remember that i've seen some anomalies as well. I've only rarely had to use boot -d. > c > x/x scbus,10 -> Symbol not found > So, looking at the ncr.c code: > > #if (__FreeBSD__ >= 2) > struct scsibus_data *scbus; > #endif Eeek. This is a local symbol inside ncr_attach(). The kernel's symbol table is limited to global (including static) symbols however. You need to figure out the stack frame offset of scbus, and have a look there. Or, you temporarily globalize the variable. -- cheers, J"org joerg_wunsch@uriah.heep.sax.de -- http://www.sax.de/~joerg/ -- NIC: JW11-RIPE Never trust an operating system you don't have sources for. ;-)
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?199602040200.DAA14870>