[B2-devel] Safe way to patch VIA base address ?

[<gb...@di...>]

Hi,

It was brought to my attention that MacMinix wouldn't run under UNIX
builds of Basilisk II in Direct Addressing mode. The problem is that
MacMinix tries to read the VIA Interrupt Flag Register located at
(VIABase + 0x1a00). But in direct addressing, this is just out of any
valid memory region.

The Windows port doesn't suffer from that problem because it simply
skips the instruction that caused the illegal memory access.

A solution may be to set up VIA to be right in the ScratchMem region.
But where could that be achieved ?

Note: MacMinix really does access to VIA by itself. i.e. It doesn't seem
to be caused by a MacOS support routine. Therefore, a runtime patch like
those in rsrc_patches.cpp is not possible.

Alternative 1: skip the instruction that caused the access to an invalid
memory region. I am a bit worried because this is too specific to the
system.

Alternative 2: just don't support MacMinix! ;-) Anyway, I am sure the
VIA registers issue will not be the sole problem with MacMinix. I am in
favor of that solution...