Re: 64-bit Mac OS X kernel
Re: 64-bit Mac OS X kernel
- Subject: Re: 64-bit Mac OS X kernel
- From: Bill Northcott <email@hidden>
- Date: Fri, 21 Aug 2009 16:06:26 +1000
On 21/08/2009, at 2:48 AM, Mo McRoberts wrote:
The PowerMac G5 shouldn't have being advertised as 64-bit if the
kernel
wasn't...
hey, even Carbon or Cocoa isn't 64bit (I don't care which API).
There are plenty of 64-bit Cocoa apps on 10.5. 64-bit libSystem-only
apps can run on Tiger, as far as memory serves. The PowerMac G5 is a
64-bit machine. It doesn't stop being a 64-bit machine if you decide
to only run 32-bit apps.
Similarly, a 64-bit _kernel_ is mostly irrelevant for the vast
majority of people. All it means in practice is that your kexts will
break.
As I understand it, the kernel in Darwin/OS X is not tightly linked to
userland code. Only kernel extensions (kexts) have to match the
architecture of the kernel. So a 32 bit Intel kernel can support 64
bit Intel code and 32 bit ppc code via Rosetta.
This has been true since 10.4 Tiger which could support 64 bit UNIX
type tools as long as they only needed a limited range of libraries.
10.5 Leopard introduced 64 bit into all libraries including the GUI.
(Cocoa on Leopard is 64 bit, Carbon is deprecated and was only ever
intended to provide temporary (9 years) support in OS X for old OS 9
apps.)
I have no NDA information on 10.6 but I think Apple has been quite
clear that it will have a 64 bit kernel and therefore require 64 bit
kernel extensions, All Apple's current hardware is 64bit. The 64 bit
kernel was not introduced earlier to avoid Vista style driver issues.
Bill Northcott
PS All this of course demonstrates the inherent silliness of people
arguing about whether some system is 32 bit or 64 bit!Attachment:
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