[Openmcl-devel] OpenMCL for x86 OS X

David Steuber david at david-steuber.com
Fri May 11 14:23:14 PDT 2007

On May 11, 2007, at 4:41 PM, Gary Byers wrote:

> There's almost certainly an easier way to tell, but one way of
> determining whether or not a Mac CPU is 64-bit-capable is:
> shell> sysctl hw.optional.x86_64
> If that returns the key "hw.optional.x86_64" with the value "1",
> then the OS believes that the machine it's running on can run in
> 64-bit ("x86_64") mode.

Thanks for the added confusion :-)  Do we blame Intel or Apple?

david at Jupiter.local:~
$ sysctl hw.optional.x86_64
hw.optional.x86_64: 1

I guess that confirms it.

> As funky as that test might be, it might be more reliable than trying
> to guess from the brand name, which might be something like  
> "Centrino II
> Pair Couplet" before long.

Please no.  Although there is already the ability to turn off one of  
the cores (I think, I didn't try to do that).

I guess this is all part of keeping the consumers on their toes.  Are  
the dual core CPUs in Dells and the like all 64 bit capable as well,  
or is Apple opting for an optional extra so that Leopard is just that  
much cooler when it comes out?

Will OpenMCL be ready for that?  I didn't upgrade to Tiger until I  
got new hardware.  My G4 was my newest machine.  I bought that in  
March, 2003.  I expect to keep this MBP for a while and am already  
very curious about at least two features that Leopard is reported to  
have: system wide GC and a versioned file system (the ad I saw showed  
going back in time to recover deleted files and even deleted address  
book entries).  I have no idea what that will do to the disk  
consumption, but I don't think it will be good.

When I fired up OpenMCL 1.1 (the latest snapshot from FTP), I think  
my whole system slowed down.  Maybe it did, maybe it didn't.  Is  
there a known issue when running a 64 bit app?  I'm wondering if the  
Intel CPU goes through expensive mode changes or something.

Other than that, I'm looking forward to the possibility of abusing a  
machine with only 2GB of RAM like no one has abused a machine  
before.  I wonder if I have enough disk space to back all the  
possible heap space <eg>.

Thanks again, Gary.

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