Boot Screen on GOP Card with Next Loader... Kind of...

abdyfranco

macrumors regular
Original poster
Dec 4, 2017
125
108
Next Loader with Development UEFI Emulator (DUET)
Reading some comments in this forum, I found that some users with non-EFI graphics cards got video output when Mac Pro was in legacy mode.

I decided to try this on my Mac Pro, using a non-EFI Nvidia GT 710 card, which was kindly donated by @two-mac-jack, And then I booted my Windows installation on Legacy mode. Because my Windows installation is on UEFI mode, I got the "No bootable device -- insert boot disk and press any key", That means the VBIOS driver of the graphics card is working and I can get boot screen on legacy mode.

I compiled and built an ISO image of DUET, then burn it to CD, DUET has the ability to emulate a UEFI environment in Legacy systems.

Once the DUET was booted, the card was initialized in GOP mode and the DUET menu appeared at my monitor's native resolution. Then I proceeded to insert the USB drive on which I have installed Next Loader and then I started the loader.efi file from the DUET menu and bingo! Next Loader loaded in UEFI GOP mode on an non-EFI card. :D

Unfortunately the joy lasted little and is that DUET is not able to detect any boot drive in the Mac Pro, no matter if it is an internal hard drive, a disk or a USB drive. :(

I'm not sure if this is a step forward in the development of Next Loader, or a step back.

 
Last edited:

DearthnVader

macrumors 6502a
Dec 17, 2015
892
4,859
Red Springs, NC
Next Loader with Development UEFI Emulator (DUET)
Reading some comments in this forum, I found that some users with non-EFI graphics cards got video output when Mac Pro was in legacy mode.

I decided to try this on my Mac Pro, using a non-EFI Nvidia GT 710 card, which was kindly donated by @two-mac-jack, And then I booted my Windows installation on Legacy mode. Because my Windows installation is on UEFI mode, I got the "No bootable device -- insert boot disk and press any key", That means the VBIOS driver of the graphics card is working and I can get boot screen on legacy mode.

I compiled and built an ISO image of DUET, then burn it to CD, DUET has the ability to emulate a UEFI environment in Legacy systems.

Once the DUET was booted, the card was initialized in GOP mode and the DUET menu appeared at my monitor's native resolution. Then I proceeded to insert the USB drive on which I have installed Next Loader and then I started the loader.efi file from the DUET menu and bingo! Next Loader loaded in UEFI GOP mode on an non-EFI card. :D

Unfortunately the joy lasted little and is that DUET is not able to detect any boot drive in the Mac Pro, no matter if it is an internal hard drive, a disk or a USB drive. :(

I'm not sure if this is a step forward in the development of Next Loader, or a step back.

Could you upload this version of DUET?
 

Rastafabi

macrumors regular
Mar 12, 2013
244
93
Europe
This is just how Clover BIOS works. It's basically loading Clover EFI using Duet. For some further testing you could just install Clover in BIOS mode to an internal MBR disk and then replace the clover files with for instance the MacLoader or rEFInd ones.

Theoretically it should even be possible to create a refind MBR EFI USB disguised as macOS, which automatically start a legacy boot residing on itself which in turn starts MacLoader or a second ordinary instance of rEFInd in the EFI/REFIND directory.



PS: I use this do enable BOOTCAMP's restart to macOS feature which does not work on APFS. – refind.conf if configured to automatically chain load macOS.
 
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