Re: debugging a kernel that doesn't start

[Robert Swindells <rjs%fdy2.co.uk@localhost>]

Edgar Fuß <ef%math.uni-bonn.de@localhost> wrote:
> I'm trying to run NetBSD on a Dell PowerEdge R6515, and the kernel is being 
> loaded (PXE or USB) but then the machine hangs hard.

Have you tried booting a custom kernel with some drivers removed?

I tried PXE booting an i386 machine today using pxeboot_ia32.bin
from -current, worked fine. Just tried amd64 now as well, also
worked.

One thing I didn't try was to pxeboot a gzipped kernel, have you
tried an uncompressed one?

> What's the way to debug a kernel that hangs so early that you can't
> printf or drop into ddb? I guess that's a phenomenon quite common for
> a new port or changes to locore.s (or whatever that's called today),
> but it's completely new to me.

The simplest way to debug something is using a serial port, do you have
access to the one on this machine?