Multiple EFI bootloaders? Windows won't let OS X boot? [SOLVED]

[destrekor]

So while I'm attempting to correct the fact that my Windows UEFI boot manager is on the wrong disk (side note below), I am also attempting to diagnose why I cannot even normally boot into another OS through it's bootloader. I have OS X installed and I can boot into it using a USB bootloader and selecting the [UEFI] USB option. But I cannot select any other OS X bootloader option. FWIW - this machine does not have Secure Boot. It is a P8Z68 Deluxe, there is no Secure Boot option anywhere in the firmware. Windows, checking under MSINFO32, also says "Secure Boot State: Unsupported". I am still going to try and play around with things and continue my research, but I am curious if anyone can provide some input that puts me on the right course, or can provide an outright solution. I want to get all of this corrected prior to upgrading to Windows 10. Since I just did a clean install of Windows 8.1 (it had been years since I had a clean install), the OS itself is very clean and lean, but I have still invested enough time to dissuade me from performing another clean install if it is not absolutely necessary, and I am not convinced it is. Windows 10 is exceptionally close to Windows 8.1 in the kernel, with WDDM 2.0 being the biggest change. If I can I'll have WDDM 2.0-compatible GPU drivers installed prior to doing an upgrade. Regardless, from reports it seems upgrading from the 8.x series has been exceptionally smooth for almost everyone, with Windows 7 proving tricky. There is enough of a gap in the kernel to turn drivers and older hardware into a frustratingly variable experience - which is not at all unprecedented for Windows releases when the kernel is significantly different. Side Note: I didn't unplug them all the non-Windows disks, so the installer decided to overwrite an EFI partition that already existed, which was a whole-disk backup of an OS X install... I don't need that bootloader I guess, it's gone now lol. I could re-create it if I cared

 

[vailr]

My advice would be: upgrade the motherboard to one with full UEFI support, such as Z97 or Z170 chipset board. Use a separate HD/SSD for each operating system, instead of using the bootloader method. Use the boot drive selector key option, which is F11 for MSI boards or F12 for Gigabyte boards.
Also note: the video card must also include UEFI support, which can be determined using the free "GPU-Z" program.

 

[destrekor]

My advice would be: upgrade the motherboard to one with full UEFI support, such as Z97 or Z170 chipset board. Use a separate HD/SSD for each operating system, instead of using the bootloader method. Use the boot drive selector key option, which is F11 for MSI boards or F12 for Gigabyte boards.
Also note: the video card must also include UEFI support, which can be determined using the free "GPU-Z" program.

Well... as for new motherboard - that's a whole new bag, and involves money. I'll be doing a Skylake or Kaby Lake upgrade whenever I am ready but I have other financial priorities.

I don't think it's an issue of UEFI support. I could be wrong, but considering I can load up EFI bootloaders, I would think this is a non-issue.

As for separate HDDs, well... that's exactly what I am doing. You have confused me, boot loaders or boot managers are needed regardless of how you have an OS installed. Drives have to have boot records to point to the OS.
I have boot loaders for each individual OS on individual drives.

edit: also my GPU does support UEFI.

 

[destrekor]

Well... this is solved. I suspect when I installed Windows UEFI, somehow it decided to overwrite the UEFI boot entries stored in UEFI. So I could try all I wanted to boot from the target "Mac" volume, but it didn't find a boot file. USB UEFI will always work, but other UEFI entries are dependent upon having a pointer stored in NVRAM. I had found some suggestions to add entries using BCFG from within a UEFI shell. So I made use of the EFI Shell within Clover, and after poking around to determine what I was working with already and what disk I needed to know, I ran the following command: Shell: bcfg boot add 6 fs2:\EFI\CLOVER\CLOVERX64.efi "Clover" That added a permanent entry within NVRAM, pointing to the Clover EFI partition and boot file. From there I can boot into Mac like I always had. I might play around with Clover and see if I would prefer it to serve as the gateway and select Windows or Mac from there, or if I might rather just let the system auto-boot into Windows by leaving the Windows Boot Manager NVRAM entry as the default boot entry, and do F8 when I want to get into Mac. (or vice-versa to save time if I want to default to Mac) I'll also have to play around to see if I can get Clover to fast-boot, to a degree, and just auto-select whichever OS had just been used, that way I don't have to worry about auto-reboots ending up in another OS. So this problem is resolved. I think I found my way out for my other issue, moving the Windows Boot Manager to the SSD. But for now, I am a very happy camper! The little wins sure do make you feel good.