Re: [hatari-devel] TOS v4 / TT-RAM issue with floppy images

[Nicolas Pomarède <npomarede@xxxxxxxxxxxx>]

Le 26/11/2017 à 23:52, Eero Tamminen a écrit :
> Hi,
>
> When running TOS tester, I came across strange problem with TOS v4.
>
> This works:
> hatari --tos tos404.img  --machine falcon --memsize 4 --addr24 off 
> --ttram 0 bootdesk.st.gz
>
> But if I change the TT-RAM amount to something else than zero,
> TOS claims that the floppy is damaged.
>
> This issue happens only with TOS v4 (not EmuTOS), and only
> when enabling both TT-RAM and floppy at the same time.
>
> With all the other configuration combinations the disk works
> fine. --fastfdc or --fast-boot options don't change anything.
>
> Disk image is one from Hatari repository:
> https://hg.tuxfamily.org/mercurialroot/hatari/hatari/file/tip/tests/tosboot/ 
>
>
> TOS error message comes when TOS autostarts the program, or
> user tries to manually run it.
>
> TOS v4 or Hatari issue?

Hi

could be a problem when TOS tries to read disk sectors into TT RAM, but 
FDC DMA counter would be limited to 24 bit and don't allow writing to TT 
RAM (IIRC the FDC DMA mask is forced to 32 bit by emulation in that 
case, but that's an enhancement to a real Falcon). I will have a look, 
maybe the mask is not correct in that case.

Wasn't there some kind of cookie that needed to be created so FDC would 
first tranfer data using DMA to normal memory, then cpu would copy these 
data to TT RAM ?

Nicolas