nick@flirble.org said:
> > Don't forget you also need to fix up pointer-to-function calling,
> > which uses the sequence 
> > 	mov	lr, pc
> > 	ldr	pc, [reg, ...]
> > For this it is important not to split the two instructions, so you
> > will need to align, do a padding nop and then emit the sequence.

> I had forgotten this. I had a thought - improved messy version is:

> 	add	lr, pc, #4
> 	.align 3
> 	ldr	pc, [...]
> 	.align 3

> which will become either

> 	add	lr, pc, #4	; return to .there
> 	andeq	r0, r0, r0
> 	ldr	pc, [...] .there

> or
> 	add	lr, pc, #4	; return to .there
> 	ldr	pc, [...]
> 	andeq	r0, r0, r0 .there


A neat idea.  This will work fine when running in 32-bit mode, but, 
unfortunately, won't work in 26-bit mode because the add will clobber the 
PSR information in the link register.


> Hopefully from the DEC document I can figure out how to make the MMU
> work, I'll do my best to do that, as
> a) this is getting really messy.

Yep.  Too many corner cases.

> b) I'd like to be able to reliably run anyone else's (legal) binaries
>    without needing to recompile to get the bodges in.

Yep.  Though for this, there is always the option of binary patching...

We await your conclusions with baited breath...

R.