Re: Removing SunOS/68k compatibility before 8.0

[Swift Griggs <swiftgriggs%gmail.com@localhost>]

On Thu, 28 Dec 2017, Frank Wille wrote:
> 1. Are there any important reasons for keeping SunOS compatibility?

I'm the type of guy who might actually have a use for something like that 
and.... I don't.

> 2. Who knows what exactly has to change for extending the virtual 
> address space?

Since the VAS is independent of the PAS, shouldn't simply increasing the 
size of the page table that tracks the virtual memory increase it's upper 
limit? I'm guessing for some reason it's not that easy. However, I can't 
think of any reason why the 68k would limit you doing that at a ISA or 
architectural level. Obviously a 32-bit register would be a limit, but 
again, that's the same as the physical address space that you can't get 
beyond anyway. We both understand that the tricks used for PAE won't apply 
to VAS.

Is there some specific malloc() issue related to the 68k ISA ? The issue 
you mention about SunOS not being able use the MSB of a pointer, I'm 
assuming you are *not* meaning one of the eight 68k address register 
A0-A7, right? I know one can't do un-aligned memory access on the 68k, but 
I am ignorant of why it would prevent extending the VAS.

> 3. Can it be done for Amiga only or would all m68k ports be affected?


> There are users who are willing to test such a modification (e.g. by 
> compiling pkgsrc, which currently fails because of low memory in some 
> areas).

If I can ever get my A3000 hardware working, I'd love to help. However, I 
don't have any 68k Sun hosts, unfortunately. I do have a few 68k Macs, 
though. One is running 7.1 right now, IIRC (a Quadra 660AV).

> Thanks in advance!

Thanks for working on these improvements. Sorry if I wasted some of your 
time, it's just that I've been working on learning 68k ASM all year and 
studying the 68k in my spare time, so I'm curious and excited about this 
topic.

Thanks,
  Swift