Installing Fedora 25 with macosx on SSD

[mcl]

I have 2012 Mac Pro with macosx on one hard drive and Fedora 25 on the second hard drive. Both OSes were
booted with rEFInd (thanks) installed from macosx. Recently, I installed Sonnet Tempo Pro card with two 1 TB
SSDs. I installed macosx earlier on one SSD and last night, I installed Fedora 25 on the second SSD. To my
suprise this monring, I found out that I cannot boot macosx anymore, even by pressing cmd + R keys. I installed
rEFInd rpm and ran refind-install, but still I cannot boot macosx.

[Roderick W. Smith]

Were you able to boot from these disks on the Sonnet card immediately after installation, but it's now failing? If so, I'm not sure what the problem is. If you were never able to boot via this card, chances are it lacks EFI firmware support; or maybe it's just slow to come up in the rEFInd menu. In the latter case, hitting Esc might bring up the entries, and if that works, setting the scan_delay option in refind.conf may get it working.

If the firmware doesn't support the card, then you won't be able to boot from disks attached to it. You should still be able to boot from a disk attached to the motherboard, though. If necessary, you could use a small disk to hold the ESP, a Linux /boot partition, and an OS X Recovery HD partition. That would probably be enough to get everything else booting.

You might also check with the board's manufacturer; they might have updated firmware for it that's more compatible with Apple's EFI.

[mcl]

I was able to boot macosx installed on SSD, earlier but on after installing Fedora on its SSD.
I suspect, that grub from Fedora took care of booting. I can only boot Fedora, which installed on one of the SSDs. I created macosx sierra installation USB,
and I will see whether I can do something about it.

I can boot macosx installed on SSD, but it is not very straighforward. The grub menu displays
in addtion to Fedora installations, two installations of Mac OSX on sdb1 drive (one 32 bit and another 64 bit) and two installation on sdd1 drive (one 32 bit and another 64 bit). If I click on any of Mac OSX entries I get three error messages saying somethin about missing commands. I can provide details later,
after I write them down. After pressing c key, I get a command line, abd after entering exit, macosx boots from SSD.