Hi Guys, I've had this AppleKextExcludeList issue happen on three separate systems now, all using different hardware that worked perfectly in Mavericks. Note, this hang on AppleKextExcludeList.kext does NOT occur on the same systems when booted through UEFI via Clover. It may perhaps be an issue with the Chimera 4.0.0 bootloader, I've been testing this for several days now. My three test systems all threw random memory allocation errors after reaching AppleKextExcludeList.kext in the boot process. The error happened without warning, at random.
Here's the workaround I found if using Chimera; its a bit of a nuisance but at least gets the system running.
1. Go to S/L/E and open AppleKextExcludeList.kext with 'show package contents'
2. Open Contents folder
3. If Info.Plist isn't visible, use ShowAllFiles app to unhide it
4. Open Info.Plist with TextWrangler app
5. Delete all entries between the <dict></dict> tags under the OSKextExcludeList key
6. Delete all entries between <dict></dict> tags under the OSKextSigExceptionHashList key
(There may be hundreds or even thousands of entries here to remove)
7. The result should look like this...
<key>OSKextExcludeList</key>
<dict>
</dict>
<key>OSKextSigExceptionHashList</key>
<dict>
</dict>
8. Exit TextWrangler and Save
9. Right Click on Info.Plist and 'Get Info'
10. Unlock the file with the little lock bottom right of the Get Info window
11. Under Sharing and Permissions change all Priveleges to 'Read Only'
12. Exit the Get Info window
13. Reset the file back to hidden with ShowAllFiles app (if necessary)
This willl have to be repeated each time permissions are repaired or Kext Utility is run. Its a rudimentary fix, I know, but at least got Yosemite booted again and prevents the system from writing to the AppleKextExcludeList.kext in S/L/E so the random boot failure is prevented.
This will likely be fixed fairly soon, but this procedure works for now.
Cheers!