Re: [B2-devel] New UAE JIT Compiler

[Christian B. <cb...@st...>]

Hi!

On Sun, Sep 03, 2000 at 01:26:06PM +0200, Gwenole Beauchesne wrote:
> (a) In order to mmap() correctly the address space in VideoInit(), I
> would like to know what is the current ROMBaseMac. This is currently not
> possible since VideoInit() is executed before Init680x0().

I think the complete part in uae_cpu/basilisk_glue.cpp, lines 59..82
(#if REAL_ADDRESSING .. #endif) could be moved into main.cpp/InitAll(),
after the call to CheckROM() has been made.

> (b) In order to get a chance to mmap() the address space as
> above-mentioned, MacRAM would not get allocated before VideoInit() is
> executed.

This is harder. I placed VideoInit() at the latest possible point in the
initialization order because it may switch to a screen mode where it's
no longer possible to put up dialog boxes for error messages from modules
that are initialized earlier.

> (d) Due to the different frame layout that could be used, I implemented
> video handling on SIGSEGV (see below). Drawback: DGA mode will be slower
> since a temp frame buffer will have to be used too.

But the whole point of DGA mode is to avoid a temporary frame buffer...

> i.e. the hack is:
> void Screen_fault_handler(int, struct sigcontext scs)
> {
>     uint32 faultive_address = scs.cr2;

I'm using a similar method to access the CPU registers in the native
NetBSD/m68k version. Unfortunately, NetBSD doesn't seem to support siginfo_t.

> TC flush will occur when:
> - Code is created and executed from Execute68k(), Execute68kTrap()
> - FlushCodeCache() is called
> - A-Traps: FlushCodeCacheRange, FlushInstructionCache
> - BlockMove()

Why is this not simply done every time a MOVEC *,CACR or CPUSH is executed
to clear the emulated 680x0's caches?

> 4. I don't want to break the CVS tree ;-)
> I don't really have a "port" so I don't know what I can change in fact.

If you are convinced that it will still work on non-x86 machines and other
operating systems (including NetBSD/m68k, where it runs without CPU emulation),
you can check it in.

> Actually, I never used CVS

There's a nice tutorial at
http://www-classic.be.com/aboutbe/benewsletter/volume_III/Issue40.html#Insight

> Should I make it the default one when an i386 cpu is detected ?

If it's an improvement, then yes.

Bye,
Christian

-- 
  / Coding on PowerPC and proud of it
\/ http://www.uni-mainz.de/~bauec002/