Re: [B2-devel] New UAE JIT Compiler

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

Hi!

On Tue, Sep 05, 2000 at 01:08:01PM +0200, Gwenole Beauchesne wrote:
> MacOS seems to try to write to ROM then read back for some testing
> purposes, right ?

There are two places I know of where the MacOS writes to the ROM:
 1. The resource manager does it when using ROM resources. But it doesn't
    seem to do any harm when the writes are allowed to take place.
 2. The longword at address 0 is set to point into the ROM (probably to
    make broken programs that write to a dereferenced NULL pointer not
    destroy any RAM contents). Unfortunately, some versions of MacOS itself
    are also "broken" in that sense and that is the main reason for the
    "ScratchMem" handling on the Amiga (otherwise, MacOS would crash on
    boot). This approach seems to be safe.

> Yes, Bernie's compiler does that but I was just wondering about
> self-modifying code and other ways to detect it and avoid complete
> checksuming of basic blocks.

MacOS will flush the cache in all instances where self-modifying code is
used (or code is loaded) when the CPU is a 68040.

> > > Should I make it the default one when an i386 cpu is detected ?
> > 
> > If it's an improvement, then yes.
> 
> Is "it works (enable scrollbars)" a right answer ? ;-)

It is. :-)

Bye,
Christian

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