Boot in 64-bit mode

I have the latest MBA and trying to boot into 64-bit mode by holding down 6 and 4 keys, setting nvram boot-args and also editing /Library/Preferences/SystemConfiguration/com.apple.Boot.plist. None seems to work. ioreg -l -p IODeviceTree | grep firmware-abi shows EFI64. Anybody else having this issue ?

Hi,
the older MBAs should not be possible to boot into 64bit mode as far as I have read, newer ones should be (see for example: http://lowendmac.com/musings/09mm/64-bit-snow-leopard.html ), though. When googling I find many negative reports... so maybe it doesn't.
Then, there are no real gains in performance if the kernel runs 64bit. 64bit apps are running on your Air anyways.
volker

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Do not upgrade to an IvyBridge processor if you need to boot into 32-bit mode with Lion

I recently upgraded to a MBP running the Ivybridge processor and tried to boot into 32-bit mode. Although it did boot after a short period (3-5 mins) it totally crashed a locked up. This was precursored by a graphics error and then the mouse cursor could be moved but nothing else could be done and it was only solved by a hard shut down (holding down the power button). Previously I had been running a MBP with the Sandybridge architecture and this booted fine into 32-bit mode and worked without a problem.
I spent a lot of time on the phone with Apple care who said they'd not had any reports of this issue and we went right though my system until they said there was nothing else they could do and I should try a re-install of Lion. I did this onto another hard-drive, booted into it and managed to get the machine to crash again... leading me to understand that it's nothing to do with my setup.
Thinking it might be an issue with my firmware on the mac today I visited an Apple store and tried booting 5 MacBook Pro's and a MacBook Air - all running IvyBridge - into 32-bit mode and managed to cause the same crash on all of them. If the machine is just booted an left with finder it didn't seem to want to crash but when I opened programs, mainly mac mail, it didn't take too much longer for the crash to occur.
If there are any Apple engineer reading this could you try and reproduce the issue and look at fixing this please as a lot of people still use 32-bit and if I'd known that the IvyBridge processors weren't going to work in 32-bit mode I would have stayed with the Sandybridge MBPs.
Many Thanks,
Adam Peters,

That is a pain then. Pretty much all of the OS included applications (finder, Mail, iTunes, Safari,...) are all fully 64-bit programs now (since Lion) so I can see where launching them when booted into 32-bit mode could cause stability issues.
If you boot into 32-bit mode and just run the Tascam software without launching anything else, will it work?
Was it alright in 10.6? And if so, how about keeping 10.6 in a virtual machine or on a separate disc or partition?

Booting in 64-bit mode.

Correct me if i am wrong:
As I understand it, when Snow Leopard is installed, it boots in 32-bit mode.
To boot in 64-bit mode, hold down 6 and 4 on startup.
I did this. Is there any way to tell I am running in 32 or 64-bit mode?
Also, once I have now booted in 64-bit, what mode will it boot up in when I restart? back to 32, or stays in 64?

Have a look here.
http://support.apple.com/kb/HT3773?viewlocale=en_US
Also, check you Activity Monitor, all your apps that can run in 64 bit -mode are already running that way. If you want to change an app, just "Get Info" (command-i) on it and you can select 32-bit mode in the check box.
-mj

Holding 3 and 2 will not boot in 32 bit mode

Hello. I need to boot in 32 bit mode to run Cisco VPN Client on my Macbook Air (version 10.7.4). This worked earlier this week but I've now tried for 3 days probably 20 plus time and cannot get it to take. Is there another way to boot in 32 bit mode?
Can anyone assit?
uname -v
Darwin Kernel Version 11.4.2: Wed May 30 20:13:51 PDT 2012; root:xnu-1699.31.2~1/RELEASE_X86_64
Thanks.

I have the identical problem:
brand new Macbook Air (Summer 2012)
Mac OS 10.7.4
Kernel patch 11.4.2
it will not boot in 32bit modus - not with holding down 3+2 during startup and neither after
sudo systemsetup -setkernelbootarchitecture i386
What´s wrong???

Mac OSX 10.6.7 don't boot in 64-bit mode

Every time I try to boot in 64-bit mode, it freezes in boot screen with the "NO ENTRY" symbol on it. When booting in 32-bit modes, it goes OK.
But I have 8GB RAM, so 32-bit + 8GBRAM = Kernel Panic.
Any ideas of how to solve it?
Best,
Marcilio

You have some 32-bit driver (that you didn't have before it sounds like).
Wherever you got the idea that OS X and some 4GB limit, each application or thread might have 4GB address space, but OS X has supported 32 and even 48GB RAM on appropriate hardware.
If this was a RAM issue, you could remove your (3rd party) RAM and still boot in 64-bit kernel mode.
As to whether your system is benefiting from 64-bit kernel mode I'd take a look at
http://www.macperformanceguide.com
To be 64-bit kernel mode everything must be "64-bit" and that means drivers, plug-ins and other items.

Can I boot into 32 bit mode on a 64 bit. If so how will this affect my 8gb ram usage?

It's basically all in the title. I was just wondering what differences there would be if I booted in 32 bit mode on my early 2011 macbook pro.

when you press the power button
hold down keys 6 and 4 (together)
till you see the apple logo and the spinning wheel.
that will enable 64-Kernel and extensions.
but honestly i think wouldnt benefit you at all.
unless your a developer and want that enable to test out your own applications/kexts.
Good Luck!

I am not having luck getting Lion to boot in 32 bit mode, what should I do?

I run Watchguard mobile VPN to connect to my work network, but the only way it runs is in 32 bit mode, I am not having luck getting Lion to boot in 32 bit mode, what should I do?

kisuke3 wrote:
Lion runs in 64bit mode. I don't think you can force it to run to 32bit mode.
You can try but quite frankly I've not seen anyone done this before
Restart your machine while pressing 3 and 2 to force it to run in 32bit mode(this was a practice in Snow Leopard)
if you ask me, my recommendation is to get Watchguard update its software to 64bit. this is the REAL solid solution for your problem. Apple does not adjust to 3rd party softwares, its the other way around.
I meant "Lion runs in 64bit mode"

My ebook reader no longer works now I have upgraded to Lion. I have reset the PRAM and tried booting in 32-bit mode, all with no joy.

My ebook reader no longer works now I have upgraded to Lion. I have reset the PRAM and tried booting in 32-bit mode, all with no joy. Come on Apple, it worked fine with Snow Leopard.
I see a lot of other people are having trouble with ebook readers, cameras, and other USB devices too.....

antonfromnelson wrote:
...Come on Apple, it worked fine with Snow Leopard...
Sorry, you're not talking to Apple here only other users like yourself.
Someone might be able to help if you post which e-book reader you are using?
Regards,
Colin R.

FYI - Snow Leopard boots in 32 bit mode by default

This seems to surprise a lot of folks, so ...
This page gives a bit more info, and has an app that could be useful.
http://www.ahatfullofsky.comuv.com/English/Programs/SMS/SMS.html
NOTE: I DO NOT recommend installing this app, as I haven't checked it out and have no idea whether it contains malware. So, perform due diligence before installing it. Always err on the side of paranoia.
But the info presented on the page is pretty useful as to which Macs have which features.
And here are a few other articles:
http://news.cnet.com/8301-13579_3-10320314-37.html?tag=mncol
http://arstechnica.com/apple/news/2009/08/latest-snow-leopard-build-limits-most- macs-to-32-bit-mode.ars
keep googling, as there are a LOT more - and eventually we'll have a good idea of which drivers work and whether things go faster or slower.

I'm more concerned that it might send serial numbers to the mothership - but, most of these apps are indeed entirely innocent. I've just been involved in the security world too long to have much trust.
Here are a few more interesting articles on 64/32
http://www.macfixit.com/article.php?story=20090826074252596
http://www.macfixit.com/article.php?story=20090828112540695

Mac Pro having issues with widgets after booting in 64-bit mode

I tried the temp 64-bit boot (holding down 6 and 4 on startup), Mac Pro boots fine. I've noticed a difference in how my system runs n 64-bit. Much peppier. But the one thing I've noticed is that widgets are coming up strange. More specifically, The Weather Network, Conversion, and Translate widgets. The letters and numbers are coming up as outlined boxes. The drop down menus still work, the names just don't come up. ie. In the Conversion widget, the drop down menu name is boxes, but when you click on it, you can see the names of the selections. But as soon as you choose one, the letters turn to boxes.
I've restarted my computer to boot back in 32-bit, and don't see the same issues. Is anyone aware of this, what's causing it, and if there is a fix? Thanks.

HI Eric,
Some widgets and browser plugins as well such as Flash aren't supported in 64-bit. Some widgets were originally written for PowerPC platforms.
Flash Player support on 64-bit operating systems
Carolyn
Message was edited by: Carolyn Samit

What is the Terminal command to determine whether booted in 32 or 64 bit mode?

I understand some newer computers are using the 64 bit kernel by default: http://support.apple.com/kb/HT3770
How do I determine via the command line whether I'm booted in 32 bit mode or 64 bit mode?

To make your Mac always start up 64 bit the only thing necessary is to alter one line of a configuration file. You can do that by opening the Terminal and entering:
sudo defaults write /Library/Preferences/SystemConfiguration/com.apple.Boot 'Kernel Flags' 'arch=x86_64'
To return to 32 bit mode, you would repeat the command but enter an empty string, which would just be the single quotes (where arch=x86_64 is) with nothing in between.
sudo defaults write /Library/Preferences/SystemConfiguration/com.apple.Boot 'Kernel Flags' ''

Trying to boot iMac in 64 bit mode, but not successful

Hello:
I am trying to boot my iMac in 64 bit mode. I have done some research and I am getting conflicting answers. Most of what I am finding says:
1. Must have an Intel Core 2 Duo: I do
2. My efi must be 64: It is
3. Must have Snow Leopard installed: I am running 10.6.2
I am running what is described as an iMac 7.1, which in theory would not be allowed to run in 64 bit mode. Also, starting up while holding the 6 and 4 keys does not force my machine to start up in 64 bit.
Any ideas/explanations as to what might be going on?
Thanks in advance.
Message was edited by: Coqui-

I don't know exactly what model imac 7.1 is but I suggest you check here on how to identify your imac
http://support.apple.com/kb/HT1758
according to this
http://support.apple.com/kb/HT3770
you need imac early 2008 or later to be able to boot into 64-bit mode. but as WBW already mentioned there is no reason to actually do it unless you have loads of RAM and some RAM hungry 64-bit apps optimized to use loads of RAM.

MacPro3,1 won't boot into Snow Leopard 64-bit mode

I'm baffled by this. All the compatibility lists I've found online state the MacPro3,1 (early 2008) models are 64-bit compatible.
I have a 3,1 mac pro, single 4-core Xeon, 8GB RAM at work, and it boots into 64-bit mode just fine.
I have the exact same machine at home, except just 4GB RAM, and it will not boot into 64-bit mode.
I have not found any documentation on this, but my only hunch at this point is that not only does 64-bit mode enable more than 4GB of addressable RAM, but could it be that it requires more than 4GB?

OK, I got it. added "arch=x86_64" to com.apple.boot.plist and it is now booting into 64-bit mode. Its just strange that holding down 6 and 4 during boot didn't work on this machine, when it worked fine at the office.
Hope this helps somebody.

Unable to boot snow leopard on 32 bit mode

I'm using Macbook pro with Mac Os X 10.6.2. And it has no problem to boot under 64 bit mode, but fails under the 32 bit mode. Is there any suggestion? Thanks.

Since most 3rd party drivers are not ready for a 64bit kernel, it is possible that when booting the 64bit kernel, a 3rd party driver, that is not compatible with 32 bit Snow Leopard, is not being loaded.

How to boot solaris 10 on SunFireV20z in 32-bit mode.

Hi,
I have installed solaris 10 on SunFire V20z (AMD).
By default it is booting in 64-bit mode. How do I boot it in 32-bit mode.
# uname -a
SunOS bangpcisol4 5.10 Generic i86pc i386 i86pc
# isainfo -kv
64-bit amd64 kernel modules
Please suggest.
Thanks & Regards,
-GnanaShekar-

How do I automate this?Run the following command with root privileges: /usr/sbin/eeprom boot-file="kernel/unix"To switch back to 64 bits, run eeprom again: /usr/sbin/eeprom boot-file="kernel/amd64/unix "Please read the man page of "eeprom" for more information.

Boot in 64-bit mode

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