Re: Unaligned access fault in fxp on alpha

Maxime Henrion wrote:
> Andrew Gallatin wrote:
> > 
> > Kris Kennaway writes:
> >  > I reported this to mux 3 days ago, but haven't heard any
> >  > acknowledgement from him of the issue.  Could someone else
> >  > investigate?  This is a reproducible panic.
> >  > 
> > 
> > Can you try this patch please?
> > 
> > It causes gcc to emit slightly different code, which deals with
> > storing to aligned 16-bit values.
> > 
> > What's happening is that because the u_int32_t link_addr (and rbd_addr)
> > fields preceded the "size" field, gcc was assuming that the rfa struct
> > would be aligned and was cheating.  It was using operations which only
> > work on aligned-32 bit values on 16-bit values.  Removing the
> > u_int32_t's disabuses gcc of this assumption, therby causing safe
> > code to be emitted.
> > 
> > I don't understand why mux changed these fields in rev 1.31, with, so
> > I'm not sure that I want to commit this until mux reviews it.  For all
> > I know, it breaks sparc64 or something..
> 
> Thanks Andrew, I should have taken care of this since some time but was
> veyr busy these days.
> 
> I removed them because they were just looking bogus.  I wanted to ask
> people to test a patch adding a __packed in the struct definition to see
> if it fixed things.  If it works with a __packed keyword, I'd like
> it better than going back to having an array of four u_int8_t.
> Otherwise I'll put the u_int8_t back.

Kris just reported to me that the __packed thing fixes things.  I'll
commit it as soon as I get re_at_ approval.

Cheers,
Maxime