I don't know about BootChamp, but you installed Windows 10 in Uefi mode, that means the disk windows is on is GUID. Apple's StartUp Disk expects a MBR disk to boot Windows, it's not finding the first stage bootloader in the disks MBR, that's why it won't work. The only solution if you want to be able to boot Windows 10 with Apple's StartUp disk, is you must find a way you install Windows in Legacy Bios mode.
I'm not sure Windows 10 is supported on a 5,1, for Bootcamp, so you may need to hack the Bootcamp.app to make a Windows 10 USB key that you can use to install Windows in Legacy Bios mode.
Really Windows 10 runs better in Uefi mode, tho the 5,1 has a custom EFI that is not fully UEFI compliant.
What I would do is create a Shell Script that "Blesses" the Windows Boot Manager EFI file, it should be on the hidden EFI partition of the disk you installed Windows to. All you would have to do, in the macOS, if you wanted to boot Windows is run the Shell script.
As to booting the macOS from Windows, when the MacOS is installed on APSF, you just need to update the Windows drivers for the ones from a newer Mac that Supports Windows 10. Used to be you could edit Bootcamp's info.plist, aand just add your Mac to the section of a mac that supported Windows 10, and bootcamp would download the later drivers and Startup disk utility for Windows, that should support APFS disks. I think Apple changed the bootcamp info.plist so it's not as easy to edit.
I'm on the road, so I don't have any mac's with me, but when I get home I'll see if I can figure out how to edit bootcamp's info.plist to "Support" your mac.
I'll check and see if I can help you with the correct syntax for a shell script to Bless Windows boot manager.
[doublepost=1510049681][/doublepost]You may need to Disable CSR, and run this command in a Terminal session:
Code:
systemsetup -liststartupdisks
See what it returns.
To disable CSR you'll have to boot from you macOS Recovery partition, there are some instructions for doing it blind, for people with PC Graphics card roms.
Do a search of the forums and you should be able to find it.
[doublepost=1510052161][/doublepost]
I think this command is what is needed, but you'll need to run:
To find the proper EFI partition, assuming you installed Windows on it's own disk, and it is formatted GUID, replace disk0s1 with the disk that diskutil list says has a "Microsoft Basic Data" partition type. You don't want to bless that partition, that should just tell you what disk. So, for example if you see a "Microsoft Basic Data" partition on disk2sX then you want to bless /dev/disk2s1, as "s1" should always be the EFI partition, it just means the first partition of disk2.
Like I say, you must use crsutil --disable from your macOS recovery partition first, because in El Cap and later the NVRAM is protected, and can't be written to, even by the root user, unless you disable it.
