Re: [hatari-devel] Emulation of the TT second MFP

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Hello everybody,

bringing up this old issue again.

I have had a look into it and it appears that the ASV Unix crash dump is misleading here. Using the Hatari debugger,
I tried to find out what happens here.

Indeed it appears to indicate the MFP involved in the crash, but actually, this seems to be a subsequent fault
(as it shows the registers from the crashdump writeout itself that is not only written to the screen but to the
serial port as well).

The root cause of the crash appears to be indeed this:

>> WARN : Write to unimplemented RTC/NVRAM interrupt enable bits 0x40

ASV seems to be using the TT RTC's timer interrupt as kind of watchdog and crashes if this does not trigger as expected.
Not sure if this is the only issue that prevents ASV from booting, but at least I would really like to give it a try.

Question is: what would it take to properly implement this interrupt? Can somebody provide pointers on where to look
best for a sample implementation of an interrupt trigger in Hatari's source code that could be used as a template?

I already peeked into the source tree but admitted, I'm a bit lost on where to start. Hints appreciated.

Thank you!

Am Montag, den 06.05.2019, 18:18 +0200 schrieb Nicolas Pomarède:
Le 06/05/2019 à 18:02, Uwe Seimet a écrit :

Interesting news. I just checked the behavior of ASV, which appears to get a
bit further in the boot process now. There is an exception, though, please
see the attached screenshot.


hard to tell what went wrong with this screenshot (and I don't know ASV 
that much) ; strange thing is that A0=FFFFFA13 in that dump, which would 
mean it was an access to main MFP whose behaviour was not modified 
(hopefully). But it's not sure the faulty access was made on this 
address, one would need to see the corresponding asm code.


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