Date: Fri, 7 Feb 1997 00:53:45 +0100 From: j@uriah.heep.sax.de (J Wunsch) To: gabor@acm.org (Gabor Kincses) Cc: freebsd-hackers@FreeBSD.ORG Subject: Re: Panic in probe, but no dump Message-ID: <Mutt.19970207005345.j@uriah.heep.sax.de> In-Reply-To: <32FA29A1.41C67EA6@acm.org>; from Gabor Kincses on Feb 6, 1997 12:57:37 -0600 References: <32FA29A1.41C67EA6@acm.org>
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(Mailing lists trimmed. Whenever you feel like posting to more than one list, you probably feel wrong. ;-) As Gabor Kincses wrote: > The problem I have is to get a dump out of the sound driver probe. I > pretty much followed the handbook on this. I have set config root on > wd2 dumps on wd2 in my config file, but no dump occurred (I checked . I Well, the normal sequence is to use `dumpon'. This is also supported by /etc/sysconfig. > 1. Is there a way to load the kernel.debug in gdb and correlate > addresses with lines of code? (Like on HP-UX w/ xdb: one can use 'td') Basically, though a little hard. Please, read the section about kernel debugging in the handbook (gdb -k aka. kgdb). > 2. Why am I not getting a core dump? No idea. What did the kernel say? Did it say ``dumping to ...''? > save the kernel core, or is it already on the swap device? Ie. what > macroscopic events would tell me that I got a dump? (Possibly: "core > dumped" msg on the console :-) Almost. Dumping to dev ...., followed by the number of outstanding megabytes to be dumped. > 3. I have turned on savecore in /etc/sysconfig, but I have noticed that > the swapon gets executed first in /etc/rc before the savecore. Wouldn't > this wipe out a core in the swap device? No. The dump is done to the end of the swap partition. > 5. Is my only option left is ddb? Your best one. Note that you can also force a dump from within DDB by saying `panic' (followed by `c'). > 6. Is a page fault essentially like a segmentation violation in user > mode? AFAIK on i386 you have to install a page fault handler, which is > probably what the VM is all about. Is this true? Well, basically. A page fault normally tries to see if it has to load a page from secondary storage. If there's no page to load, it will be reported. By a SIGSEGV to a user process, by a panic (or a jump into DDB) in the kernel. > 7. Why is the "dumps on" feature being deprecated? How else can we get > a dump if the system crashes before dumpon can be executed? BTW, My That's where you need `dumps on'. Apart from this, it's deprecated since it requires a kernel modfication while dumpon(8) doesn't. -- 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. ;-)
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