24" iMac Screen Freezes since 10.6.3 update - pls help!

STEP-BY-STEP GUIDE TO APPLY THE ATI KEXT FIX FOR 7,1iMacs 8,1iMacs & “VINTAGE” MACS THAT SILL HAVE FREEZES WITH THE ATI GRAPHIC KEXTS FROM 10.6.2 RUNNING ON OSX v10.9.5 MAVERICKS

I want to thank all those involved certainly KrysztofTurek for finding the original 10.6.2 kext fix. Other honorable mentions Freandc, aieronimo&TK111. I want to thank Freandcfor writing most of this. I have changed some of the wording to assist with the 7,1iMac some 8,1iMacs and other “Vintage” Macs. who still experience freezes in Mavericks. Follow this procedure to get the KrysztofTurekKext Fix solution to work on older “Vintage” Macs running OS X 10.9.5

Subsequently additional updates to OS X may require the following procedure to be repeated or a portion thereof.

Usually just removing new AMD kext installed with update

After Updating to Mavericks 10.9.5

1.Download Cindori Kext Drop here:

https://s3.amazonaws.com/cindori/KextDrop.dmg

2.Download the 10.6..2 ATI kexts here:

• http://blog.krzysztof-turek.com/wp-content/uploads/2012/04/10_6_2atikext.zip
• Unzip to a non-system location, i.e. your desktop or home folder.

3.Use Apple Menu->About This Mac and click the “More Info” button to determine which version of the ATI Radeon Card is installed.

• I have only had direct experience with the ATI 2400 in a iMac7,1.
• I believe Freandc has direct experience with the ATI 2600 in a iMac8,1 (Freandc if I'm wrong correct me)
• Both the ATI2400 & ATI2600 were available in iMac 7,1 & iMac 8,1 among other Macs

4.I recommend logging in as root user so all changes will be systemwide.

• To learn how to login as root user go here:
• http://support.apple.com/kb/PH14281
• CAUTION!!! Any changes made as root user not mentioned here may damage machine.
• Logout and login in as root user.

5.Those who are experimenting this fix with other cards pay close attention as you may still have other kext that are needed to operate your graphics card.

• Mavericks has renamed the ATI kexts to AMD kexts .
• REMOVE ALL the AMD kexts to a safe backup location NOT JUST COPY from here:
• /System/Library/Extensions
• Kexts will load alphabetically and the AMD kexts will load before the ATI kexts if not REMOVED.
• If you have the affected ATI 2400 & ATI 2600 graphics card there is still one ATI kext (ATIRadeonX2000) that loads.
• There are known problems related to it please leave the ATIRadeonX2000 kext installed.

  LION USERS REMOVE all ATI kexts from /System/Library/Extensions folder except for the ATIRadeonX2000 kext.

6.Run Cindori Kext Drop downloaded in STEP 1 and drag the kexts downloaded in STEP 2 into the primary text area.

• The kexts you want are:
  • ATIFramebuffer.kext
  • ATISupport.kext
  • ATIxxxxController.kext -->(where xxxx refers to the type of card you have)
• Click install and enter your password where indicated.

7.The 7,1 iMac, some 8,1 iMacs & other Vintage Macs that are capable booting the kernel in 64-bit, but whose kernel boots in 32-bit by default when v10.6(snow leopard) was/is the OSX. I implore you to test my theory in step 8 which may help those early iMac who have the 10.6.2 kexts installed in Mavericks and are still experiencing the freezes.

• SKIP TO STEP 9 Only if your Mac boots the kernel in 64-bit by default while running OSX v10.6
• If you're unsure which kernel your Mac boots while running v10.6 go here:

  http://support.apple.com/kb/ht3770

• If your Mac is not on the list then it boots the kernel by default in 32-bit while running v10.6
• To see why the kexts will or will not load dependent on the kernel go here:

  http://support.apple.com/kb/ht4287

8.Mavericks already boots the kernel in 64-bit and the 10.6.2 kexts released by Krysztof Turek are supposed to run in a 64-bit environment but I believe that these older Macs fail to load all or a portion of the 10.6.2 kexts in Mavericks.

The solution that has worked for me is to tell the EFI to boot the kernel in 64-bit mode by running the terminal command:

sudo systemsetup -setkernelbootarchitecture x86_64

• Hit enter and close terminal
• I realize in Mavericks the kernel already boots in 64-bit by default but the terminal command given modifies: /Library/Preferences/SystemConfiguration/com.apple.Boot.plist with the following kernel flag:

  <string>x86_64</string>

  • It and will take effect every time you start up from this disk.
  • If you start up from a different disk, the default setting on that disk will take effect.
• To remove the kernel flag simply navigate to /Library/Preferences/SystemConfiguration/com.apple.Boot.plist and delete the x86_64 between the string markers.
• I know there are other ways to tell the EFI to boot 64-bit while running OSX v10.6(such as holding down “6” and “4” key while booting but this is required every time you boot up the machine and thus not very convenient).

  I don’t know if the are other ways that still have same outcome.

  • If other ways produce the same outcome work then they may be useful to YOSEMITE USERS who use the same Boot.plist with the kernel flag below which allows unsigned kext to be used.
    • <string>kext-dev-mode=1</string>
      • YOSEMITE USERS please see Question C at end of tutorial.

9.Reboot and Login in as REGULAR USERand DISABLE!!!! ROOT USER

To confirm changes have taken place:

ALL USERS

• Go to "Apple Menu"-->Click "About This Mac"-->Click "More info"-->Click”system Report"
  • On the left hand panes list of components select-->Software-->Extension
  • Locate the ATI kexts you should see all three kexts and their loaded status should say yes.
  • And the version number for the three that were installed should be 1.6.6
• In addition to the three kexts you have installed some users may see:

  ATIRadeonX2000 kext has loaded with a different version number

  • I believe this ATI kext is still updated by Apple and I would leave it along.
  • To this date there is no issue with the ATIRadeonX2000 kext running on the system.

EFI 32-bit USERSwho had to follow STEP 8 to boot the EFI in 64-bit kernel permanently.

• Go to:

  /Library/Preferences/SystemConfiguration/com.apple.Boot.plist

  • To confirm the change has taken place the plist should appear as:
    • <string>x86_64</string>
• If the solution has worked for you please post with your Mac model, Graphics Card model & OSX Version you tested on

QUESTIONS I STILL HAVE FOR ANY OF YOU OUT THERE

Please reply to this post with your:

Answer to questions A,B or C, your Mac model, Graphics Card model & OSX Version

A.Can any other iMac, MacBook, Mac Mini or MacBook Air users confirm that the theory has worked for you?

B.Has someone found this theory to work with Graphics Card Freezes other than the ATI 2400 or 2600 cards.

C.YOSEMITE USERSDoes the Terminal command code which allows the loading of unsigned kexts in Yosemite work in conjunction with the kernel flag implemented in my theory?

• If so what does that Boot.plist looks like if they work in conjunction and how to implement them.
• Or does the Kernal flag: <string>kext-dev-mode=1</string> do the same thing as the theory in step 8?

D.Does anyone know what bearing the ATIRadeonX2000 kext has on ATI 2400 & 2600 cards?

If so. Do other ATI kext still load on other machines? i.e.other affected Graphics Card Freezes theory may helped prevent freezes.

Swmaster

Does adding the kext-dev-mode=1 between the string markers allow OSX v.10.9.5(mavericks) or other OSX that will normally only load 64-bit kext to use 32-bit kext?

As this may answer my Question C. in the tutorial above.

swmaster:

I haven't had time to try your method. Busy at the moment.

But I would like to know if you experience the same as Teardropcarnival (post above). He uses the 2007 imac:

" After applying the "kext-dev-mode=1" fix and rebooting, the lag seemed to be resolved. However, I ultimately ended up losing my 2nd display via the midi-DVI connection as well as finding several small display issues such as: no program names showing up when you hover over the icons in the dock, choppy text and icons in stacks in the dock, and some other less than desirable side effects."

Tazthed:

Did you see my tutorial about the 7,1 iMacs and other "Vintage" Macs and their EFI and the 10.6.2 kexts running in a 64-bit environment.

Yes I saw your very long tutorial... did I miss something?

Do you think that the 10.6.2 kexts do not load properly in Yosemite even after flaging the Boot.plist with "kext-dev-mode=1" which allows the use of unsigned kext in Yosemite. Because some older macs (7,1 my direct experience) the EFI boots the kernel in 32-bit by default when the running OSX is v10.6? They do not load properly in Mavericks on the 7,1. because the 7,1 booted the kernel in 32-bit when the OSX was v10.6 which is close to 10.6.2 kext the the last known working kext for the ATI 2400 or 2600 Graphics cards. If has worked for Mavericks it may for Yosemite.

I have the 8.1 imac from 2008 and I wonder if the side effects also appear when loading the kext in Yosemite on iMac 8.1. Because if it doesn't have the side effects then maybe it has something to do with (like you wrote) the 7.1 iMac booting in 32 bit?

I just checked my 8.1 iMac and it boots in 64 bit by default. The problem is that I am working on a project at the moment and don't have time to backup and try Yosemite. When I take a break I come here to read about this freezing problem 🙂

I Believe the Xserve is the only Mac prior to 2009 the booted the kernel in 64-bit by default in v10.6. All other Macs are capable of booting OSX v10.6 when told to do so (given they have a 64-bit processor). Some still boot in 64-bit by default but only OSX v10.6 Server. And other Macs like the Mac Book and Mac Pro got a patch to boot 64-bit by default with OSX v10.6. I don't believe that the 8,1 defaults to 64-bit. Did your 8,1 experience freezes in mavericks?

You are right - iMac 8.1 does not use 64 bit kernel by default, but it supports the 64-bit kernel.

When I check what kernel my iMac uses in the Terminal I can see that it uses 64 bit.

Yes, my iMac 8.1 had freezes in Mavericks. Then I applied the original kext files from 10.6.2 (and removed the AMD kexts) -> no more freezes. I did not need to tell my EFI to boot in 64 bit.

Sorry there's a bad link in Step 7

7.The 7,1 iMac, some 8,1 iMacs & other Vintage Macs that are capable booting the kernel in 64-bit, but whose kernel boots in 32-bit by default when v10.6(snow leopard) was/is the OSX. I implore you to test my theory in step 8 which may help those early iMac who have the 10.6.2 kexts installed in Mavericks and are still experiencing the freezes.

• SKIP TO STEP 9 Only if your Mac boots the kernel in 64-bit by default while running OSX v10.6
• If you're unsure which kernel your Mac boots while running v10.6 go here:

  http://support.apple.com/kb/ht3770

• If your Mac is not on the list then it boots the kernel by default in 32-bit while running v10.6
• To see why the kexts will or will not load dependent on the kernel go here:

  http://support.apple.com/kb/ht4287 IT SHOULD BE: => Mac OS X: 64-bit kernel frequently asked questions <=

If a moderator would like to fix the link and delete this post that would benefit all!

A 64-bit Processor in a Mac on any version of OS X(except v10.8) EFI can boot a kernel in basically 3 different architectures: i386, 64 & x86-64.

Prior to 2009 OS X booted every Mac's EFI booted the kernel in i386, except the Xserve by default booted x86-64, and some MacBooks and MacPros after receiving a patch mid way through OS X v10.6(Snow Leopard) defaulted to x86-64.

• i386 is a 32-bit kernel.

  A 32-bit kernel can run both 32/64-bit apps, hardware,etc. but only 32-bit kext for apps, hardware,etc will load.

• 64 is, well, a 64-bit kernel.

  A 64-bit kernel can run both 32/64-bit apps, hardware,etc. as long as the 32-bit kext are either, replaced or, patched to a 64-bit kext.

  • If not replaced or, patched to 64bit the 32-bit kext for apps, hardware,etc. will fail to load.
• x86-64 is a Hybrid kernel

  A Hybrid kernel can run both 32/64-bit Apps as well as 32/64-bit kext.

• OS X v10.6(Show Leopard) EFI is capable of booting all 3 types but defaults to i386.
• OS X v10.7(Lion) EFI is capable of booting all 3 types but defaults to i386.
• OS X v10.8(Mountain Lion) EFI is only capable of booting 64.
• OS X v10.9(Mavericks) & v10.10(Yosemite) EFI's are capable of booting all 3 types but default to 64.

Now I know some users have gotten the 10.6.2 ATI kext to stop the freezes in different versions of OS X. The reason for this is the 10.6.2 ATI kexts floating around have been developed into a "hybrid' kext. But, kext can only be written 32-bit or 64-bit. What we know is those kext were originally written in Snow Leopard and then modified by someone in an attempt to be able to load them as 64-bit or "hybrid." Regardless the outcome the 3 kext may say their loaded to a 64-bit kernel but all or some of the coding within each(controller, framebuffer or support) kext may or may not all working properly (freezes, doesn't freeze & overheats then freezes). These kext may be working for some users right now but may not for future versions of OS X and beyond as this has been shown for some users cannot update beyond a certain version of OS X.That all said the way to get the v10.6.2 ATI kext to work is to tell the EFI to boot a x86-64 kernel as described in Step 8 of my tutorial 2 pages back in this tread. But if the kext are flawed then loading the originals in a x86-64(Hybrid kernel) if you can get them may be the best bet. Or better yet if kext from one of theMacBooks or MacPros that had the affected graphics card in them that received the patch mid way through OS X v10.6(Snow Leopard) where patched by apple for a 64-bit kernel.

Couldn't wait any longer - I just upgraded from Mavericks to Yosemite. I installed the original kext files from 10.6.2 and deleted the AMD kext files.

I added "kext-dev-mode=1" in the "/Library/Preferences/SystemConfiguration/com.apple.Boot.plist" (thanks to swmaster).

I rebooted -> No problems! Everything runs smoothly!

I also checked that the original kext files were installed correctly.

Computer model: iMac, 24 inch, from 2008.

Update on your Yosemite install?

It is still running fine. No freezing issues or any graphical issues. Seems like Yosemite is faster than Mavericks.

Just for your information my iMac 8.1 boots in x86_64.

I have a 20-inch mid-2007 iMac with an ATI Radeon HD 2400 XT graphics card. It is currently running Yosemite, with the ATI v1.6.6 kexts instead of the AMD v1.28.29 ones in the Extensions folder.

To get these to load, I used Terminal to run this command, recommended by in this forum, in Terminal:

sudo nvram boot-args=“kext-dev-mode=1”

About This Mac shows the architectures of the ATI kexts provided via this forum as “i386, xm86_64”. So I took no specific steps before restarting to boot into 64-bit mode.

My experience after updating to both Mavericks and Yosemite was similar to some other contributors to this thread. I had a bit of a fingers-crossed honeymoon period, but then random freezing and crashing started after about a fortnight. And once it had, the machine then became impossible to use for more than a few minutes.

I now seem to have got it back. No thanks to Apple, of course, but to all the diligent work by the expert troubleshooters in this forum.

The question is, if they can come up with a relatively simple solution, why can't the highly paid -- and increasingly smug -- geniuses at Cupertino?