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

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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?


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.


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