Re: CVS commit: src/sys/arch/m68k/m68k

[Nat Sloss <nathanialsloss%yahoo.com.au@localhost>]

On Sat, 5 Apr 2025 22:32:10 Martin Husemann wrote:
> On Sat, Apr 05, 2025 at 10:01:37PM +1100, Nat Sloss wrote:
> > Following advice and following the spirit of my intentions adding nop in
> > the switch i added nops before "rte" in locore.s in sys/mac68k as
> > opposed to m68k/swicher.
> 
> This makes no sense to me (but I can only guess how the exact bug works).
> My naive guess would be that *any* instruction after a f-line instruction
> would do, and whenever we do something in the kernel at the critical
> point we are safe anyway.
> 
> I would *guess* that placing the additional NOPs in userland only should be
> enough.
> 
> Martin


Before I placed the additional nops before rte I experienced 1 hard lockup 
which I attributed to the fpu (buggy lc)

The idea was this:

nop
fnop

could be executed as

nop
(context swtich)
(return from context swtich)
fnop

So without these the fnop would not be coverted.

It's working though....If there are any other test you could recommend to give 
the cpu/fpu traps a workout I'm eager to try them.


Best regards,

Nat