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4475 Views 17 Replies Latest reply: Oct 30, 2009 8:07 AM by tsaw
Currently Being ModeratedSep 11, 2009 5:17 PM (in response to Jeffry Herwig)I'm in the same boat as you my friend. Mine is a 20" mid 07 iMac, dual intel 64bit processor, and yes I checked in the terminal to verify that it is EFI64 capable. My model is an iMac 7,1. I just confirmed that you need an iMac 8,1 and newer to boot into 64bit mode. I really don't know what the difference between the 7,1 and 8,1 are. Anyone know anything about this? I can only hope that a firmware upgrade will fix this. I've upgraded to 10.6.1 today, and would really like to try out 64bit mode.iMAC, Mac OS X (10.6), Aluminum 2.4 Ghz Intel
Currently Being ModeratedSep 11, 2009 8:28 PM (in response to eROCK1)Man, I have like the exact same model mac as you. No luck here, either.Mac OS X (10.6)
Currently Being ModeratedSep 12, 2009 2:08 AM (in response to Jeffry Herwig)I had exactly the same problem with my iMac 9.1 untill i found this http://seiryu.home.comcast.net/~seiryu/sixtyfourswitcher.html
it's freeware and with me it works perfect, you canchoose how to start (32 or 64 bit) in system preferencesImac 9.1, Mac OS X (10.6)
Currently Being ModeratedSep 12, 2009 9:45 PM (in response to wimf)But unfortunately most of us here have iMac 7,1's.
Currently Being ModeratedSep 14, 2009 9:05 AM (in response to Jeffry Herwig)I have the exact same issue with my imac 7.1.
Not able to get 64 bit to boot.Mac Mini, Mac OS X (10.5)
Currently Being ModeratedSep 14, 2009 12:06 PM (in response to wimf)How is that any different than editing the boot.plist yourself? You don't need an application to edit a single line of text in a specific text file for you.Mac Pro, 8 Core, 32 GB RAM, nVidia Ge 8800 GT, 2 TB storage, 30'' Cinema Display, Mac OS X (10.6), 24'' iMac, 13'' Aluminum Macbook 2.0 GHz, 3G iPhone
Currently Being ModeratedSep 15, 2009 10:41 AM (in response to Jeffry Herwig)I just got off the phone with Apple about this. According to Apple, the only hardware that they are "officially supporting" for 64 bit bootup is the XServe servers, and the Mac Pro desktops. So no iMacs or laptops. Now, that doesn't mean it won't work...just means Apple doesn't support it. So what I've found in my investigation, is that iMac 7,1 will not work, but iMac 8,1 and newer will boot into 64 bit mode.
I asked Apple if a future firmware release will fix this for older dualcore intel iMacs, and they could not answer that. All I got was a "maybe".
So guys with the iMac 7,1 like myself, all I can tell you is to keep your eyes and ears opened for Mac news about this. Keep reading the forums too. I would love to extend the life of my iMac (which really isn't even that old)and make full use of the 4 gigs of RAM I've installed by booting into 64 bit mode, but I'll have to wait for now. Apple really should not have misled the world about Snow Leopard and the HW that they support in regards to 64 bit boot mode. Boo Apple.iMAC, Mac OS X (10.6.1), Aluminum 2.4 Ghz Intel
Currently Being ModeratedSep 15, 2009 10:52 AM (in response to eROCK1)You can still run 64 bit applications and make use of the 4 GB of RAM you have in your iMac.
True the kernel itself is 32 bit (which means it is slightly slower than 64 bit one - system calls are slower but you most likely do not spend lots of your time in the kernel code), but on the other hand do you really need your kernel to use more than 4 GB of your 4 GB of RAM :D?
On the other hand great majority of apps are 64 bit in Snow Leopard and your iMac (same as mine) will run them just fine.Mac Pro, 8 Core, 32 GB RAM, nVidia Ge 8800 GT, 2 TB storage, 30'' Cinema Display, Mac OS X (10.6.1), 24'' iMac, 13'' Aluminum Macbook 2.0 GHz, 3G iPhone
Currently Being ModeratedSep 15, 2009 11:23 AM (in response to MarioGrgic)It still isn't cool of Apple to advertise that if you have a Mac with an intel processor, you will be able to boot into 64 bit mode. Very misleading.
This page here talks about the future of computing with 64 bit mode etc,
but to code snow leopard to boot in 64 bit on some intel macs and not others, well, is just plain bad. Apple's way of forcing the little guy to buy newer hardware in a few years? Maybe.iMAC 7,1, Mac OS X (10.6.1), Aluminum 2.4 Ghz Dual Core Intel
Currently Being ModeratedSep 15, 2009 11:27 AM (in response to MarioGrgic)Actually, there is nothing inherently "faster" about a 64-bit kernel versus a 32-bit kernel. At least not when kernel RAM is not limited (which with anything less then 32GB it certainly would not be). System calls are NOT slower. In fact, with only 4GB of total RAM, a 32-bit kernel may be faster, since it has less overhead then a 64-bit kernel (64-bit loads 64-bit registry's and memory page space, regardless of whether it really needs them to manage the available resources).2.53GHz MacBook Pro unibody, 2.8GHz 8Core Mac Pro 10GB RAM, 1TB HD, Mac OS X (10.6)
Currently Being ModeratedSep 15, 2009 11:48 AM (in response to eROCK1)I dont see anywhere on that page where it says "if you have a Mac with an intel processor, you will be able to boot into 64 bit mode.". It says if you have a Mac you can run 64-bit applications. It also says "Snow Leopard takes the next big step by rewriting nearly all system applications in 64-bit code" Notice - nearly all, so there are some Snow Leopard applications that will remain 32-bit for now. On my iMac I have 49 processes running 64-bit and 10 processes running in 32-bit. Of the 10 running 32-bit, 8 are not apple applications.
warning my opinion: They don't run the kernel in 32-bit to force you to buy new hardware, they code the Snow Leopard kernel to run in 32-bit on some systems to protect the old systems and old applications from failure.
..bobiMac 24" 3.06 Ghz 4 Gb, Mac OS X (10.5.5)
Currently Being ModeratedSep 16, 2009 1:27 AM (in response to Jeffry Herwig)*IMac 7.1 is not yet capable to boot to 64 bit kernel,.*
*refer the description below*
If your Mac is on this list, you can force Snow Leopard to boot into 64bit mode by holding down the '6' and '4' keys during the boot process. You can also use the NVRAM or the com.apple.Boot.plist file to more permanently boot into 64bit mode. Holding the '3' and '2' keys will, obviously, boot Snow Leopard in 32bit mode.
Lets Just Hope Apple will relase a firmware upgrade to make IMac 7.1 capable to boot to 64 bit Kernel, Hope They Dont forget us
For any further clarification..
firstname.lastname@example.org only chatimac 20, Mac OS X (10.5.1)
Currently Being ModeratedSep 16, 2009 5:04 AM (in response to Michael Black)Actually, 64 bit kernel is inherently faster (the system calls are 250% faster according to Apple), and there is a good technical reason for that as well.
"while all other common 32 bit operating systems like Linux, Windows and the BSDs
split the address space into 2 GB for user and 2 GB for kernel (2/2) or 3 GB for user and 1 GB for kernel (3/1), the i386/x86_64 version of XNU uses a 4/4 split: While the kernel is running, the user's data is not mapped into its address space, and while user code is running, the kernel is not mapped. So user and kernel can each have 4 GB of address space with the disadvantage of being less efficient in copying of data between user and kernel. But this way, kernel mode can map more devices into its address space (like video cards with a lot of memory), and manage more RAM"
This limitation (slow mapping of user data into kernel address space) is completely gone with 64 bit kernel.
Now how much speed up will you see from 64 bit kernel? Well it depends on what kind of code you run and how many system calls (calls into the kernel it makes). Look at your activity monitor during your typical computer usage and see the red graph in the CPU monitor tab (the System CPU usage). If you spend a lot of time there, then 64 bit kernel will have good impact on your overall performance.Mac Pro, 8 Core, 32 GB RAM, nVidia Ge 8800 GT, 2 TB storage, 30'' Cinema Display, Mac OS X (10.6.1), 24'' iMac, 13'' Aluminum Macbook 2.0 GHz, 3G iPhone