Re: 64 bits support
Re: 64 bits support
- Subject: Re: 64 bits support
- From: "Justin C. Walker" <email@hidden>
- Date: Sun, 2 Nov 2003 09:16:35 -0800
On Sunday, November 2, 2003, at 07:30 AM, Scott Thompson wrote:
I'm not sure what this means; can you clarify? Note, in particular,
that Darwin does *not* have a microkernel architecture - it's a
monolithic kernel.
Darwin is based on the Mach Microkernel which shares and address space
with a BSD-like monolithic kernel.
I think you are referring to the "normal" use for mach 3.x, which is as
a microkernel. The Darwin kernel is not that kind of kernel. It is
more like mach 2.x in its "tight coupling" with the rest of the
BSD/IOKit kernel.
I don't know for sure that it's even possible to write a "server OS", a
la Mach 3.x, with the Darwin kernel.
It should be possible, to replace the Mach VM-descended memory
management processes with an alternative memory handler and that, in
theory, might allow you to allocate larger blocks of memory.
You could still replace the memory management subsystem, but it would
be pretty ugly :-}. It would not be a simple, surgical strike (if
there ever could be such a thing).
It should be possible... I didn't say it would be practical. :-)
Even if you rewrite the memory handling, I believe (and anyone is
welcome to correct me) but I believe you will still be limited to 56
bits.
The 56-bit thing is a physical capability for some latter-day G4's.
This just allows the system to support more physical memory, and has
no effect on what an individual process can directly access.
Unless, of course, you take control of the segment registers and VM
tables yourself by rewriting the memory subsystem.
That would be the "bank-switching" approach I mentioned. No matter
what else you do, you can't give a process more than 32 bits of address
space (at one time). The G5 will eventually change that limitation (I
assume).
Regards,
Justin
--
Justin C. Walker, Curmudgeon-At-Large *
Institute for General Semantics | "Weaseling out of things is
what
| separates us from the animals.
| Well, except the weasel."
| - Homer J Simpson
*--------------------------------------*-------------------------------*
_______________________________________________
xcode-users mailing list | email@hidden
Help/Unsubscribe/Archives: http://www.lists.apple.com/mailman/listinfo/xcode-users
Do not post admin requests to the list. They will be ignored.