Subject: Re: savecore
To: Quaizar Vohra <>
From: Chris G Demetriou <>
List: port-alpha
Date: 08/25/1996 19:48:41
> 	I am trying to debug a kernel on an alpha 3000, 300. When the
> system crashes, and I reboot, savecore complains about bad device

"you're not going to like these answers..."

> > bad dev 809
> Can someone help with the details about configuring savecore. I
> rather have no understanding of how savecore works.

savecore currently does not work on NetBSD/Alpha.

> Also when I try to compile the current version of ddb, I get 
> warnings and errors. Is there a patch or something I am missing.
> I have an alpha running NetBSD which I booted from the rz25 disk
> image and then compiled current sources.

and neither does DDB.

> Also if someone can give me adequate pointers about getting
> info. about kernel debugging, it would be a great help. Atleast
> some idea of where to start from. I would be deeply indebted.

I use printf to track down repeatable problems.

To track down randomly-occuring crashes:

	(1) note the PC and RA printed on panic, and

	(2) when you reboot, run GDB on the "netbsd.gdb"
	    produced by your kernel build.  then 'disass'
	    the PC and RA provided.  that will at least
	    tell you where the kernel crashed, and (in
	    many cases, though definitely not always)
	    what function called that function.

If you're sufficiently tricky, you can figure out where
the kernel crashed, down the to exact source line...
I do this by (in gdb) saying: break <file:line>, noting
the resulting address, and looking for a pair of lines
whose addresses in the code bracket the crashing address.

I really should get DDB working...  but i don't have much time to work
on Alpha stuff, these days, and _my_ machines don't crash.  8-)
There's also the fact that if i wanted to make DDB work well, i'd have
to teach it about ECOFF symbols, and i just Don't want to deal with

If the crashes you're seeing are in 'stock' kernels that i've
supplied, then i'd be (very) interested in helping you find the
problem, especially if it's repeatable.  If that's the case,
please get in touch with me privately.