Re: [hatari-devel] EmuTOS boot freeze with Hatari git on 040/060 + MMU

[Nicolas Pomarède <npomarede@xxxxxxxxxxxx>]

Le 13/03/2024 à 23:06, Nicolas Pomarède a écrit :
> Le 13/03/2024 à 21:31, Christian Zietz a écrit :
> > Christian Zietz schrieb:
> >
> > > - According to my "git bisect" the breaking commit within Hatari is:
> > >
> > > commit eb4467638e926af2c3d9b4e23da9917fbbf1d2d6
> > > Author: Nicolas Pomarède <npomarede@xxxxxxxxxxxx>
> > > Date:   Tue Sep 19 22:36:28 2023 +0200
> >
> > I suppose the problem lies somewhere here: 
> > https://github.com/hatari/hatari/commit/eb4467638e926af2c3d9b4e23da9917fbbf1d2d6#diff-b285c31d41bc9b04586496a1ee1f4ae69b738da8f018aa512f844c7faf41a3d4R3291.
> >
> > The vector number (in this case for the Timer C IRQ) is put into "nr", 
> > but later on, the original value saved in "vector_nr" is used to 
> > lookup the exception vector, essentially incorrectly making this 
> > interrupt an autovector interrupt.
> >
> > Note that the code uses "nr" and "vector_nr" in multiple places. I did 
> > not check if there are other places where one of the variables is used 
> > incorrectly.
>
> Hi
>
> thanks a lot for bisecting this.
>
> I'm the one who sent Toni a patch for WinUAE in the case where MMU is 
> used, because it was not handled correctly before.
>
> in the case of the Amiga it uses vectored interrupt, except the vectored 
> interrupt doesn't change, ie nr = vector_nr, so swapping nr with 
> vector_nr was not noticeable in normal Amiga use, but in the case of 
> Atari it was when MFP provides its own vector
>
> But as you notice there're several places where nr and vector_nr are 
> used and it's quite possible I forgot to replace one with the other for 
> correct vectored result.
>
> I will have a look at the whole MMU part to check this.

Hi

stupid bug spotted and fixed, please try the attached patch on current 
devel sources, it should use the correct MFP vector in case of interrupt
(iack_cycle() result was incorrectly saved in 'nr' instead of 
'vector_nr', as in Exception_mmu030() )

Nicolas

diff --git a/src/cpu/newcpu.c b/src/cpu/newcpu.c
index b3bc64ee..2919c603 100644
--- a/src/cpu/newcpu.c
+++ b/src/cpu/newcpu.c
@@ -3294,7 +3294,7 @@ static void Exception_mmu (int nr, uaecptr oldpc)
 
 	interrupt = nr >= 24 && nr < 24 + 8;
 	if (interrupt)
-		nr = iack_cycle(nr);
+		vector_nr = iack_cycle(nr);
 
 	// exception vector fetch and exception stack frame
 	// operations don't allocate new cachelines