MP 1,1-5,1 Boot picker for non-MacEFI Vega 56

[imrazor]

I'm trying to figure out how to enable a multi-boot setup on my MacPro5,1 with a graphical boot screen and a PC Vega 56. (Heck I'll take a text based boot screen if it's dead simple to set up. Will GRUB even work on a Mac? Can you install and use GRUB without Linux?) Here's the catch: I do not want to use EFI shims like OpenCore, Chimera or Clover. I used to use Hackintoshes and it was a world of pain for me. I want to stay far, far away from any kind of EFI hackery.

So is there an easy way to do this? Or does it require diving into the EFI partition and mucking around with config files?

Current configuration:

MacPro5,1
Single Xeon X5680
OWC 512GB SSD w/ Mojave
WD easystore 240GB SSD with MBR install of Windows
Seagate 5TB data drive
WD 2TB drive with VMware ESXi 7.0u3

I can get all this to play nice if I use my flashed Sapphire Radeon HD 7950. However when I try to use the Vega I cannot select ESXi at all - not even blindly. I'd like the Vega for the better performance, and to at least try to get GPU passthrough working. The Sapphire was a complete bust with macOS.

 

[sfalatko]

I'm trying to figure out how to enable a multi-boot setup on my MacPro5,1 with a graphical boot screen and a PC Vega 56. (Heck I'll take a text based boot screen if it's dead simple to set up. Will GRUB even work on a Mac? Can you install and use GRUB without Linux?) Here's the catch: I do not want to use EFI shims like OpenCore, Chimera or Clover. I used to use Hackintoshes and it was a world of pain for me. I want to stay far, far away from any kind of EFI hackery.

So is there an easy way to do this? Or does it require diving into the EFI partition and mucking around with config files?

Current configuration:

MacPro5,1
Single Xeon X5680
OWC 512GB SSD w/ Mojave
WD easystore 240GB SSD with MBR install of Windows
Seagate 5TB data drive
WD 2TB drive with VMware ESXi 7.0u3

I can get all this to play nice if I use my flashed Sapphire Radeon HD 7950. However when I try to use the Vega I cannot select ESXi at all - not even blindly. I'd like the Vega for the better performance, and to at least try to get GPU passthrough working. The Sapphire was a complete bust with macOS.

You need to look at OpenCore. If you haven't done it already read through the first post in this thread - OpenCore on the Mac Pro. If you don't want to tackle setting it up your self look at the options in the "additional resources" section of that first post.

One suggestion would be to get a bootable USB stick and setup OpenCore on that. You can test it out and see if it works the way you want without messing up your current install.

One complication for you is your legacy (MBR) install of Windows. OpenCore can only boot a UEFI install of Windows. My solution has been to use OpenCore from a USB Stick to boot BigSur and use the normal Apple boot process to boot Mojave and my legacy install of Windows 10.

Regards.

 

[KeesMacPro]

I'm trying to figure out how to enable a multi-boot setup on my MacPro5,1 with a graphical boot screen and a PC Vega 56. (Heck I'll take a text based boot screen if it's dead simple to set up. Will GRUB even work on a Mac? Can you install and use GRUB without Linux?) Here's the catch: I do not want to use EFI shims like OpenCore, Chimera or Clover. I used to use Hackintoshes and it was a world of pain for me. I want to stay far, far away from any kind of EFI hackery.

So is there an easy way to do this? Or does it require diving into the EFI partition and mucking around with config files?

Current configuration:

MacPro5,1
Single Xeon X5680
OWC 512GB SSD w/ Mojave
WD easystore 240GB SSD with MBR install of Windows
Seagate 5TB data drive
WD 2TB drive with VMware ESXi 7.0u3

I can get all this to play nice if I use my flashed Sapphire Radeon HD 7950. However when I try to use the Vega I cannot select ESXi at all - not even blindly. I'd like the Vega for the better performance, and to at least try to get GPU passthrough working. The Sapphire was a complete bust with macOS.

Refindplus will provide a bootscreen and is meant for multiple OS setup , including a legacy Windows install.

MyBootMgr: RefindPlus|OpenCore

This is a guide to using OpenCore and RefindPlus, to multiboot Classic MacPros (3,1 to 5,1) as well as equivalent Xserve (2,1 and 3,1). It involves booting Mac OS from one or more OpenCore instances chain-loaded from RefindPlus and booting other OS types directly from RefindPlus. The guide is...

forums.macrumors.com

If you live in Europe , another option could be to have your Vega flashed by MVC Europe in Poland.

 

[imrazor]

I tried installing MyBootMgr and it really didn't like my APFS Mojave boot disk. For some reason the tool insists on using an ancient HFS+ disk for a boot volume. So I'm not sure how to proceed with that.

Another issue is both the solutions mentioned above involve OpenCore. As I've said, I'd like to avoid that for historical reasons (Hackintosh hell) and I am also not sure if the EFI hacks involved will interact with ESXi safely.

The MBR Windows install isn't a lost cause. See here:

MBR2GPT

Use MBR2GPT.EXE to convert a disk from the Master Boot Record (MBR) to the GUID Partition Table (GPT) partition style without modifying or deleting data on the disk.

docs.microsoft.com

I have used this tool successfully on Wintel PCs before, but am a little unsure how well it will work on a Mac Pro.

Unfortunately I am not in Europe, so having my Vega flashed is not an option.