Re: Patch: hppa lazy FPU switching and QEMU bugs

[Thor Lancelot Simon <tls%panix.com@localhost>]

On Tue, Aug 18, 2026 at 06:09:20PM +0100, Nick Hudson wrote:
> 
> On 18/08/2026 00:11, Thor Lancelot Simon wrote:
> > On Mon, Aug 17, 2026 at 06:27:43PM +0100, Nick Hudson wrote:
> > > It doesn't quite work - I saw an unexpected core dump and fp exception. Will investigate more later...
> >  From a user process, or of the kernel itself?
> 
> Only userland problems.
> 
> I'm happy to take a diff the just does eager.

I am still just barely gaining comfort with the architecture and the
asm syntax and I think that'd take a little more restructuring in
trap and locore to be what I'd call a clean finished result.  But
I don't mind poking at it later...

I think I see the problem with eager mode.  I was testing it only
with the workload that caused me problems with lazy, namely,
integer multiplies!  So I was getting away with not properly
handling the FPU status register, which the lazy path kind of
does as a side effect (really, the lazy path is nothing but
side effects, depending how you squint at it).

I'm fixing.  Will send another patch.

-- 
Thor Lancelot Simon	                                     tls%panix.com@localhost
  "Indeed, someone who is a citizen in a democracy is often not one in
   an oligarchy."
					- Aristotle, Politics III.1