Kernel Panic on DREAMPLUG: Alignment Fault 1

[Ian Lepore]

On Thu, 2013-08-01 at 04:29 +0200, Mattia Rossi wrote:
> On 01/08/13 00:31, Ian Lepore wrote:
> > On Wed, 2013-07-31 at 17:38 +0200, Mattia Rossi wrote:
> >> Hi all,
> >>
> >> this might be related to the WLI-UC-GNM Alignment Fault, but definitely
> >> has nothing to do with Wireless LAN.
> >> It rather seems that there's a problem with the USB subsystem.
> >>
> >> See dmesg an backtrace below.

> >>[snip]
> >>
> >> Currently trying to find where the issue could be.
> >>
> >> Mat
> > This is a strange abort, and if it's usb-related that's only accidental
> > I think.  It says it's an alignment fault, but the fault address reg has
> > a 32-bit aligned value in it.  That makes me think it must be an
> > ldrd/strd instruction (requires 64-bit alignment) that's faulting.
> >
> > Is this compiled with clang?  I think it emits such instructions and gcc
> > doesn't.  Except I don't think clang should use those instructions on
> > armv5, because of the alignment requirements.
> >
> > -- Ian
> Hi Ian,
> 
> sorry, forgot to add that contrary to the WLI-UC-GNM problem, I'm still 
> compiling using gcc on FreeBSD 9.1
> 
> The abort is completely reproducible each time at the same place...
> I've tried to recompile the kernel a few times, also changing the root 
> device, but it gets stuck there and aborts..
> 
> I actually have no clue on what's going on here. Any hints on how to get 
> more information about this?
> 
> Cheers,
> 
> Mat

Actually, it looks like you're using clang (I keep forgetting this comes
out in dmesg now):

>> FreeBSD 10.0-CURRENT #9 r253846M: Wed Jul 31 17:24:31 CEST 2013
>> root at freebsd9.1-base:/usr/obj/arm.arm/usr/devel/dreamplug/sys/DREAMPLUG-100m
>> FreeBSD clang version 3.3 (tags/RELEASE_33/final 183502) 20130610

Is the 'M' in r253846M anything significant?

I haven't built for dreamplug in a long time (I haven't done much of
anything with computers for several months).  I'll get a build going and
see if I get the same kind of problems.

-- Ian