[B2-devel] SheepShaver updates

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

Hi,

I have just committed changes from my old local tree to CVS:
- For better MacOS 8.6 support, you may have to turn on fake 
SCSIGlobals in rom_patches.cpp. I reckon this is a workaround.
- There is now a new PowerPC emulator checked in. This is from a toy 
experiment from a few months ago. With the emulator SheepShaver crashes 
just before MacOS 8.6 loads up extensions. I don't know yet whether 
it's due to a bug in the core or the glue to SheepShaver. If someone is 
willing to proofread the core, he is welcome. ;-) Last time I read it, 
I spotted out only 1 or 2 bugs and the test Linux/ppc programs I have 
handy still work fine. So, it could just be a pb in the SheepShaver 
glue code.

The ppc emulator is not sophisticated yet and features only a basic 
predecode phase. This is to evolve but I first wanted to fully boot 
into MacOS. Slow down factor is still around 25 vs. native code on 
average, as measured on my PB G4 @ 400 MHz.

Concerning cache invalidation, this is simply not handled yet. The plan 
is to mark pages read-only on icbi instructions, then write to those 
will actually clear caches (predecode cache, native code cache). Due to 
the way cache invalidation works on ppc  (icbi/isync/etc.), this is the 
best idea I came up with. Feel free to suggest others.

Note: this will compile on x86 but won't work until little endian fixes 
are checked in too. ;-)

Bye,
Gwenole.