[OpenBIOS] Even more findings to report about booting Mac OS 9

Segher Boessenkool segher at kernel.crashing.org
Sun Apr 17 03:52:55 CEST 2016

On Sat, Apr 16, 2016 at 09:40:04PM -0400, Tarl Neustaedter wrote:
> On 2016-Apr-16 21:14 , Segher Boessenkool wrote:
> >> > One possible solution; take the boot-script code, and rather than
> >> > interpret it directly, try compiling it.
> > That does not work.  The OS9 bootscript contains many definitions as well.
> > Not just colon definitions.
> I thought the other definitions should work inside a colon definition.
> Unfortunately, I no longer have access to an openboot to test against (I
> retired late last year).

A trivial example is

1000 constant pagesz
pagesz 1- constant pagesz-1

If you put that inside a colon def, the second pagesz will error when
the colon def is compiled (the word hasn't been defined yet).

> > In summary, the two things you need:
> >
> > -- Parse the bootscript line by line.
> > -- Have a separate interpretation mode R stack.
> >
> The separate R stack is probably the harder issue.

It isn't hard to implement /an sich/.  Both Apple OF and OFW (and thus,
openboot) already have it.  It will however uncover shortcomings in
your text interpreter :-/


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