Re: Another illegal instruction awk problem

["Michael L. Hitch" <mhitch%lightning.msu.montana.edu@localhost>]

On Fri, 6 Aug 2010, der Mouse wrote:

> > > > (gdb) x/i 0x80196183
> > > > 0x80196183 <emodd+120>: movd r9,r0
> > > emodd - I think that's one of the often-emulated inestructions,
> > > meaning ragge is almost certainly right.
> > So then... how should I go about figuring out why the emulated
> > instruction didn't get emulated?
>
> Oh, it's not that it didn't get emulated.  It was in the process of
> being emulated when the fault occurred; that's what the PC inside the
> kernel's emodd code indicates.
>
> However, I have trouble seeing how "movd r9,r0" could fault showing
> SIGILL.  While I don't have the -5 source at ready hand, the 4.0.1

  My guess would be that it's trying to move a 'NaN', which someone had
decided should be a value that causes a reserved operand fault on the vax. 
The reserved operand fault generates a SIGILL to the process.  I'd have to 
see the contents of the source register to be sure.

--
Michael L. Hitch                        mhitch%montana.edu@localhost
Computer Consultant
Information Technology Center
Montana State University        Bozeman, MT     USA