Re: [hatari-devel] 68040/060 MMU bug fix

[Nicolas Pomarède <npomarede@xxxxxxxxxxxx>]

Le 28/12/2023 à 17:59, Toni Wilen a écrit :
> Hi
>
> Just a note that few hours ago I fixed nasty and normally rare random 
> 68040 MMU emulation bug. If interrupt was pending (and interrupts were 
> enabled) when bus error handler executed RTE (and handler had interrupts 
> disabled by setting imask=7), interrupt's first instruction was 
> "retried" instead of the faulting instruction. Normally not that serious 
> (but can cause problems in some situations) because RTE from interrupt 
> handler would "retry" it  anyway but if both are MOVEM to memory, then 
> interrupt handler's MOVEM used faulted MOVEM's pre-calculated EA.
>
> 68060 does not have this MOVEM EA feature but in some situations it can 
> also cause bad results. 68030 is not affected because it does not 
> restart instructions.
> (https://github.com/tonioni/WinUAE/commit/0be6d4eaca09acdb838c0c6ea45c57267c8f4cce <https://github.com/tonioni/WinUAE/commit/0be6d4eaca09acdb838c0c6ea45c57267c8f4cce> unfortunately I included some do_specialties() clean ups in same patch, just ignore it)


Hi,

thanks for pointing it, I noticed it also this morning and was planning 
to merge it in Hatari (as for the cleanups in same patch, it's not a 
problem, I will also apply it to keep as close as possible to WinUAE's 
sources :) )

As you say, it seems a rather rare case, I don't think we hit this in 
Hatari.

Nicolas