I installed Window 8 RTM build 9200 on my 2012 MBP with native EFI booting, and had plenty of problems (including BSODs) when driver security verification (can’t remember the exact wording) was on. I disabled it and Windows seemed stable. I would still get a kernel security failure crash at times. The audio bus didn’t work either. It was unreliable. Windows wouldn’t boot every time I needed it. After some poking around, I found out that a faulty driver was causing Windows 8 to crash. Booting in safe mode alleviated my problems. However, Windows isn’t very functional in a permanent safe mode. With the next semester approaching, Windows needed to be reinstalled in a BIOS configuration.
The first problem was GPT (GUID Partition Table- it organizes the partitions on a disk). When installed for EFI, Windows 8 requires GPT. Since the Mac OS transitioned to X86, it has required GPT. Both function just fine side-by-side. It becomes an issue when you want to install Windows with EFI being in legacy mode. When a Mac boots Windows from the disc, the first (and normal) option is to act as if the Mac is a PC with a regular BIOS. It emulates a BIOS. In this setting, Windows requires that the disk use an MBR (Master Boot Record). In general, only one can be used at a time. Apple’s solution is to create a hybrid partition that makes it seem as if the disk is using MBR, but it is actually within a GPT disk. Boot Camp does this automatically. Boot Camp will only do it if you have a single HFS+ partition, though. I already had a partition. I just needed to convert it. I used gptsync to create a hybrid partition. Something messed up. Windows 8 reinstalled properly, but it converted the entire disk to use MBR. That rendered my entire Mac OS 10.8 installation and the recovery partition useless. Thankfully, I made a backup.
After an incident with my hard drive during an earlier semester, I created a backup partition, a recovery partition, a data transfer partition, and a boot partition on an external disk. Those were a lifesaver. All I had to do was boot into the recovery partition and restore my Time Machine archive. I was impressed. After it was done copying everything back to my reformatted hard drive, my MBP rebooted right back where I had left off. Only a few user passwords and preferences were missing. Now that I had a single HFS+ partition, the process was easy (as with most things if you do it the Apple way). Windows 8 is now happily running on my MBP 13″ Mid-2012.
At present, forcing Windows 8 to function with the Mac EFI is a struggle. It is unsupported and adds more headaches than any performance. I will note that the Windows 8 installation process is much easier than before. The post-installation screen even looks better than it ever has. Regardless, Windows 8 with bootX64.efi just doesn’t jive with my MBP yet.