Re: How to get a crash dump with recursive panic?

[Eduardo Horvath <eeh%NetBSD.org@localhost>]

On Thu, 12 Jun 2014, Darren Reed wrote:

> On 10/06/2014 1:45 AM, Eduardo Horvath wrote:
> > On Mon, 9 Jun 2014, Darren Reed wrote:
> > 
> >> In testing out ipfilter on sparc64, I see a bunch of "Alignment error"
> >> messages like these:
> >>
> >> Alignment error: pid=24522.1 comm=ipfstat dsfsr=00000000:00800001
> >> dsfar=ffffffff:fea0c252 isfsr=00000000:00808000 pc=10e3b0
> >> Alignment error: pid=22537.1 comm=ipfstat dsfsr=00000000:00800001
> >> dsfar=ffffffff:fea02252 isfsr=00000000:00808000 pc=10e3b0
> >> Alignment error: pid=6845.1 comm=ipfstat dsfsr=00000000:00800001
> >> dsfar=ffffffff:fea02252 isfsr=00000000:00808000 pc=10e3b0
> >>
> ...
> > 
> > Trap type 0x34 is an alignment trap.  The instruction in question is 
> > trying to load an 8-byte integer pointed to by %g4+0x20 into %g4.  You can 
> > enable DDB and dump the registers to find the contents of %g4.  That 
> > should not be 8-byte aligned.
> 
> Is there an easy way to drop into ddb when this error happens?
> A sysctl that I can set?

Yes.  Just before you do whatever causes the alignment error, break into 
ddb and set `trapdebug' to 0x100.

Eduardo