Re: [B2-devel] B2-JIT from UAE-JIT "Ipswitch Town" approaching

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

Hi,

> > PS: Christian, could you please rerun your tests for "Julia's Dream" ?
> 
> This seems to work fine now, but I get lots of random crashes with the
> emulator. The average runtime is about 30 seconds before it crashes
> (usually "do_handle_screen_fault: unhandled address", but also "Illegal
> instruction"). This is on a PIII with Debian 2.2 and gcc 2.95.2.

Yes, I also noticed that for small translation cache sizes. e.g. 256 KB
or 512 KB. With a much higher cache, say 8 MB, things are more stable
and also much faster.

As for the cause to the problem, I am pretty sure it is related to the
way I handle spcflags and the condition/process to get out of compiled
code once a real ("hard") translation cache flush occured. I had
experimented a few other approaches but with no avail :-/

It's probably not related to spcflags after all. You know, I find pretty
hard to debug B2 because I can't use gdb. Indeed, whenever I set up a
breakpoint, gdb would not stop and finally makes B2 to exit with a (-1)
return value. Therefore, I am currently condamned to read and re-read
the source code and experiment a few things with runtime disassemblers
and some other techniques I am not proud of...

> > PPS: I removed compiler.{cpp,h} in my sources. Do you still want those
> > for future normal B2 releases (CVS) ?
> 
> Anything that is unneeded can go.

Actually, the JIT compiler normally does 68020 up to 68040. the original
compiler was to support 68000 only. Is it worth "supporting" that CPU ?
How many people do really emulate a Classic Mac ? ;-)

> > B2-JIT only does 68040 though it should also work for 68020 and 68030
> > cpus, but actually doesn't...
> 
> Caching issues?

Yes, probably. I already had that problem in the past and fixed that in
a previous release. The problem is that I don't remember how since I was
fixing other bugs I thought unrelated to that problem. i.e. some day, I
wanted to try in 68030 mode again and it automagically worked... But
there is definitively a cache problem since the JIT compiler would also
get disabled forever once the Desktop shows up.