[hatari-devel] Re: Problem when switching from ST to Falcon mode

[Nicolas Pomarède <npomarede@xxxxxxxxxxxx>]

Le 29/05/2016 à 16:32, Thomas Huth a écrit :
>  Hi Nicolas,
>
> I recently hit a strange bug with the new WinUAE core in CE mode. It
> does not always occur, but approximately every third time that I try it,
> I can see the bug:
> I'm starting Hatari from scratch, without config file (i.e. I renamed
> my hatari.cfg so that the emulator does not find it), in ST mode with
> TOS 1.02, i.e. "./hatari --tos tos102uk.rom emtyfloppy.st".
> After a couple of seconds, once the desktop appeared, I press F12 to
> enter the menu, then I only select tos404.rom in the ROM dialog, click
> OK again in the main dialog and in the two warning dialogs that appear,
> informing me that the machine has to be resetted and that the machine
> type has been changed to Falcon mode.
> When the machine now booted to the Falcon desktop, everything seems to
> be in slow motion - e.g. when I enter the pulldown menu at the top of
> the screen, I can see how each plane is drawn separately.
>
> I'm trying to find the reason for this bug since a couple of days, but
> so far, I failed (I suspected something wrong with the CPU or blitter
> cycles, but I did not see anything unusual so far). Do you have by any
> chance an idea what could be wrong here?

Hi

I already had this slow motion bug, but was unable to reproduce it so far :(
I have a few leads though, since this happens only in CE mode, I 
sometimes saw some traces where global cycle count is not aligned on 4n 
cycles anymore, but 4n+2, while other parts still expect 4n, which gave 
bad result ; this seems to be triggered at interrupt / exception time, 
maybe when previous instruction takes 4n+2 cycles.

I can't say for sure if it's related, but I think I can reproduce it 
more often ; so maybe once I fixed this the slowness will disappear 
(maybe going from ST to Falcon increase the problem, but when just 
starting in ST mode I see it very less often than 1 out of 3 times)

I don't think it's blitter-related, because I saw it sometimes in STF mode.

Nicolas