bootstra.tos broken on 68040/68060 real hardware

Hi,

I have been playing with Debian/m68k for a few days on my Atari Falcon with CT60. Maybe you are aware of the fact that CT60 TOS (basically a patched TOS 4.04) also contains its own version of ataboot (based on ataboot 3.3 from 2004).

This built-in ataboot was able to boot 2.2.25 from Debian Sarge 3.1 just fine, with -T 0x8000000 even without -s (2.4.x, as you perhaps remember, is unable to boot without -s due to internal changes fixed much later).

However that ataboot doesn't contain the important update from late 2004 which allowed to use the staging area also outside ST RAM, drastically limiting how big the kernel+initrd can be. For 2.2.25 it was fine, for Debian 10 or 12 it was way too little.

So I switched to bootstra.tos/prg, unchanged since 2011 but in reality the same code base as m68kboot from linux-m68k. To my surprise, not only I couldn't get any new kernel booting (Debian 10, 12, some snapshot from 2023) but the 2.2.25 using the same bootargs wouldn't boot.

After some digging I have found the culprit: for all those years, the data cache hasn't been flushed! A simple fix: https://github.com/mikrosk/m68kboot/commit/c6408a2e37fe9d43ad964f09fefcbed9aad361bc made ataboot.ttp working again.

I guess one of the reasons why this bug went unnoticed is that Debian/m68k now lives mostly in Aranym which doesn't implement copy-back caching of the 68040.

Now to figure out how to make the installer read the ISO ... Debian 3.1's one just scanned Atari TOS C:, D:, ... drives, Debian 10's (and later) for some reason refuses to do the same.