Comments on: PAE vs 64 bit – What manufacturers don’t want you to know

By: Ben

Ben — Mon, 31 Oct 2011 15:24:15 +0000

I just bought a cheap all-in-one pc. It has Windows 7 32 bits installed. CPU is AMD E-350 1.6GHz. It came with 2GB of memory and added another 4GB, so a total of 6GB memory. I enabled PAE using bcdedit command as described. The bcdedit /enum shows the setting after the system was rebooted. Total memory always shows 6GB. Usable memory reported has dropped a little bit since enabling PAE to 2.61GB. First, will PAE work with this AMD CPU? Second, how can I find out whther PAE is doing its magic and is using all 6GB memory?

Thanks!

By: Pacoup

Pacoup — Fri, 20 Aug 2010 23:20:58 +0000

wow, thanks lol. Never noticed.

So, did you meant 10.6 runs its Kernel in 64 bit? Because all the 10.6 computers I have run in 64 bit, no matter what the processor (all Intel processors on Macs are 64 bit capable), just the Kernel isn’t running in 64 bit yet, which is eventually going to get changed by Apple… one day.

And while Apple hardware has no problem running 64 bit Windows, you have to be careful as older machines are not supported in 64 bit on BootCamp, despite being capable of doing so. It doesn’t prevent you from doing it, it’s just that Apple doesn’t have proper drivers for it, so getting the webcam to run is a bit harder than just putting a CD in.

In Activity Monitor, you have to display all processes, not just user processes, in order to determine if you’re running 64 bit in the Kernel as well. Some Apple apps, notably iTunes, as well as a couple of services, aren’t fully 64 bit yet. I believe this is the case on Windows as well, except Windows 64 bit has always been Kernel 64 bit, hence the major pain in driver upgrades a while ago, which is not so much of a problem these days though as hardware manufacturers have pretty much moved on.

By: Aaron

Aaron — Tue, 17 Aug 2010 15:35:58 +0000

Mac OS X 10.6.x runs in 64-bit mode on Core2Duo or later processors. On older CoreDuo processors (like my first-gen MacBook Pro) runs in 32-bit mode.

To verify you’re running in 64-bit mode, go to Applications > Utilities > Activity Monitor. It will display all your running processes and whether they’re 64-bit, 32-bit, or PowerPC emulated (upgrade your software already!).

Apple hardware has no problems running Windows in 64-bit mode (via Bootcamp or virtualization) and Linux in 64-bit mode (not just PAE).

-Aaron-

PS: Your slash on step 12 of your XP instructions is the wrong direction.

By: Yuhong Bao

Yuhong Bao — Sun, 03 Jan 2010 01:21:27 +0000

“In a few years, systems will already be exceeding 64 GiB of memory”
Actually, PAE support as much physical address space as long mode does.
On Windows’s licensing limits, here is an article by Geoff Chappell:
http://geoffchappell.com/viewer.htm?doc=notes/windows/license/memory.htm

By: Ted

Ted — Sat, 26 Sep 2009 00:44:33 +0000

@ gawdfadda

But yea DEP also uses 36bit and its a kernel hog too isnt it?
and that’s enabled by default, but PAE ins’t so what up with that then..

By: Pacoup

Pacoup — Thu, 24 Sep 2009 01:26:09 +0000

Well, I have to admit it was just for the sake of the title -_-… I don’t really think PAE is really a solution either. If anything it’s just a temporary gimmick.

Still, it’s part of this world, as Apple still is running Snow Leopard in 32 bit on the kernel level as of 10.6.1 you know. Anyway, most of the time I haven’t actually been able to make it work well and I’d just recommend to anyone to simply get 64 bit and get over with 32 bit and Windows XP now that Windows 7 is coming out.

By: gawdfadda

gawdfadda — Wed, 23 Sep 2009 21:45:45 +0000

I find this hard to swallow as anyone who understands the memory management model will realize that PAE also hobbles your system in a 32-bit world. It cuts your Free Page Table entries down to about 10% and the pools drop to half of what they originally were set. This in turn, causes performance issue at the kernel level. Microsoft did not necessarily try to hide this. They simply do not want this level of information going out to those who would implement without a good understanding. As far as Apple goes, Mac is a home user system at this point, or for graphics, and really cannot be discussed in this venue as it does not, nor will it ever, apply. Apple can stick to blowing up Ipods, lolol.

By: Pacoup

Pacoup — Wed, 09 Sep 2009 22:56:02 +0000

I’ll have to do research on this, thanks.
(For perplexed readers, he’s talking about the Intel Core 1, not the Core 2, which are all 64 bit capable)

Other note I’ll have to check on, actual OS X, even Snow Leopard (until an update comes out for that) still run their kernel in 32 bit mode. Wondering how Apple managed to make things 64 bit without breaking anything? The answer: they never did.

By: Chris

Chris — Fri, 04 Sep 2009 04:41:22 +0000

Note that first gen Intel Macs use 32 bit Core Duo processors

By: Pacoup

Pacoup — Mon, 06 Jul 2009 15:04:41 +0000

Here you go, I added the information which states that you don’t have to do anything for that in OS X. As long as your hardware supports it, your Mac OS X supports it.