pci pause: SDXC
I upgraded roughly 40 iMacs to Yosemite late last year. About 15% of them are having boot problems. Viewing the boot process in Verbose mode shows the process stalling with a 'pci pause: SDXC'. I have trawled the web and found very little info about this, I'm kind of surprised that it's not happening to others on a larger scale as I don't think I have anything unique going on with our Macs here. All the iMacs vary in age so it's not machine type specific [core 2 duo up to i7], some were upgraded from Lion, some from ML, some from Mav. Common 3rd party software is limited to MS Office 2011, Acrobat Reader, Firefox, Chrome, Symantec Endpoint and VLC player - not exactly dangerous stuff.
Posts on the web point to an fsck error specifically around kext. One helpful post suggested dumping the Startup folder from the System/Library/Caches folder. That does work, but just the once, as whatever error is causing the problem gets written again after startup and you are back to square one if you reboot. In some instances re-installing the system software works, but the problem has re-emerged in those instances too, so also back to square one.
I'm going to erase the HD on one iMac, do a fresh install and start installing site specific 3rd party software one by one, re-starting on each occasion to see if this problem occurs after a particular piece of software gets installed.
If anyone out there [hello Apple] has any info on this issue, I'd be glad to hear about it.
iMac, OS X Yosemite (10.10.1), 2.7 Ghz i5, 16GB Ram