Re: [hatari-devel] VBL warnings from Hatari on MegaSTE 8->16Mhz change

[Eero Tamminen <oak@xxxxxxxxxxxxxx>]

Hi,

On 3.6.2025 23.31, Nicolas Pomarède wrote:
> Le 26/05/2025 à 13:29, Eero Tamminen a écrit :
> > I mailed the CPX.
>
> the issue was in fact general to any machine, not just MegaSTE, as soon 
> as CPU speed was changed on the fly (without a subsequent reset). The 
> cycle counter related to the current VBL was then offset by 64/68 cycles 
> during the current VBL.
>
> This was harmless but it's fixed anyway with a somewhat smaller/cleaner 
> code than before

Thanks!

I tested switching (MegaSTE) CPU speed both by using GENERAL.CPX (in 
desktop), and with debugger "setopt --cpuclock <x>" command (during 
STDOOM demo playback), and both worked fine.

=> will add autostart support also to CPU clock option.


	- Eero

> Nicolas
>
>
> > On 23.5.2025 14.30, Nicolas Pomarède wrote:
> > > Le 22/05/2025 à 23:08, Eero Tamminen a écrit :
> > > > Hi Nicolas,
> > > >
> > > > It tried running latest Hatari git with (EmuTOS v1.3 +) MegaSTE 
> > > > emulation.
> > > >
> > > > I think (Emu)TOS sets CPU to 8Mhz initially, but when "general.cpx" 
> > > > configuration changes MegaSTE to 16Mhz, or 16Mhz+cache during, I see 
> > > > lots of warnings like this:
> > > > cyc since vbl old 177270 != new 177338
> > > > cyc since vbl old 177364 != new 177432
> > > >
> > > > They stop only when EmuTOS desktop is reached.
> > > >
> > > > Few more of those warnings come if I change at runtime from 8Mhz to 
> > > > 16Mhz in the CPX.
> > >
> > > Hi
> > >
> > > these warnings are from the change to remove CYCLES_COUNTER_VIDEO, to 
> > > ensure the new counter method work as before.
> > >
> > > They are harmless when you have only 1 ou 2 of them after changing 
> > > some settings, but I will have a look to try to fix these (it could 
> > > be more problematic for demos using precise cycle synchronisation)
> > >
> > > Could you send "general.cpx" or give a link to it, in order to have 
> > > the same context as you ?
> > >
> > > Note for emutos : would be great to have directly an option to change 
> > > MegaSTE 8/16 Mhz or cache from the emutos desktop :)
> > >
> > > Nicolas