I was trying to install drivers for my NEC USB 3.0 PCI card. ( propably http://sourceforge.net/projects/genericusbxhci/files/ or https://github.com/RehabMan/OS-X-Generic-USB3 )
I rebooted my mac into kext-dev-mode=1
then i typed: sudo kextcache -m /System/Library/Caches/com.apple.kext.caches/Startup/Extensions.mkext /System/Library/Extensions
GenericUSBXHCI .kext was enabled. Two other .kext too.
After restart - my usb 2.0 and usb 3.0 was working fine! Pendrvive was copying files very fast.
But unfortunetally magic mouse won't connect, so i restarted Mac Pro.
Now, booting is frozen. Sometimes at 1/3, sometimes at 1/2 I can't enter the Recovery Mode or Single user mode.
I was trying every possible ctrl+r, windows+r, alt+r, shift combinations on my logitech usb keyboard, but Yosemite just won't boot.
After freeze, computer reboots, and white screen of death appears. Over and over again.
I have Yosemite installation disk image on my pen drive and Mavericks installator on my external hdd, but i wasn't able to start it.
I don't event know if efi sees my keyboard.
Maybe keybindings are the problem, cause i normally use oldshool DIN-5 mechanical keyboard from 1980' But the shortcuts from this keyboard won't work too.
What can I do to enter command line or repair .kext's ?
I have no other mac/pc to connect the hard drive.
UPDATE: First success: Linux Mint booted and it's working fine. I can read my Mac SSD drive! So i assume that hardware is all right. Even magic mouse is working under linux.
I have discovered installer.faliurerequests file on Mac drive. It says: Operation fsck target CrashAtProgress 0
After rebooting from linux to Os X it was working like 10 minutes, artifacts appeared on the screen, and then crash again. Next time it was working only 2 minutes... and now i can't boot it again.