apple moving to x86

John Baldwin jhb at
Fri Jun 10 16:41:26 GMT 2005

On Jun 9, 2005, at 7:21 PM, Stephen Hurd wrote:

> John Baldwin wrote:
>> On Jun 8, 2005, at 10:30 PM, Stephen Hurd wrote:
>>>> As there is FreeBSD port to the PowerPC and its peripherals, this 
>>>> machine will make a very interesting target for FreeBSD: combine 
>>>> the x86 code base with the PowerPC drivers and get a real hot 
>>>> machine.
>>> The *really* hot machine is going to be the OSX ABI supported under 
>>> FreeBSD and running Aqua.  I betcha this happens FAST.
>> I doubt it would be fast at all if it even happens.  Unlike Linux, 
>> svr4, and ibcs2, OS X is not just a POSIXish UNIX kernel.  It also 
>> includes mach so there would have to be a lot of emulation to support 
>> that.  OS X also tends to define its interface not at the kernel 
>> syscall level but at the library API level (from what I have heard), 
>> which means that it might require having custom versions of the base 
>> system frameworks ala Wine which would be an enormous amount of work.
> But the ABI support is about emulating the kernel ABI, not about 
> emulating the kernel.  Since the *nix userland is mostly FreeBSD 
> afaik, the ABI must be pretty darn close already.  If the interface is 
> via libraries, that makes it MORE likely not less to happen fast... 
> unless I misunderstand something.  ABI emulation doesn't replace the 
> libraries.  You'd still need a copy of OSX to run OSX binaries that 
> used the shared libs (Just like all the other ABI emulations).

Two things.  First, OS X's kernel ABI includes things like Mach IPC, 
etc. that would require a good bit of code to emulate.  Secondly, since 
OS X's ABI is at the library level, they are freer to change the kernel 
ABI within a 10.x "branch" making it harder to get an ABI that will 
work with all versions of Panther or Tiger for example.

John Baldwin <jhb at>  <><
"Power Users Use the Power to Serve"  =

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