Mac Mini 2018 + eGPU boot screen support in Catalina 10.15 Beta 5
Until Mojave the Mac Mini had no boot sector/boot screen support when the Display was attached to an eGPU.
I just installed Catalina beta 5 which updated the Mini's firmware during installation. Now my Mini 208 seems to have proper boot selector and boot screen support through eGPU (wich means a nice shiny high resolution Apple logo displayed on my 4K display during boot or the standard boot selector when pressing the Option key before boot). Not all roses yet, since usually instead of the login screen the OS boots to a blank white screen (I have to turn the eGPU on and off briefly to get the login screen), but the direction of the change is most welcome! I did not test this, but probably this change means proper FileVault login support as well!
I updated two of my headless Macs to Catalina Beta 5 last night. The 2013 Mac Pro was tested with newest builds of Purge-Wrangler. The 2018 Mac mini was not tested but I'm very excited to hear your update. Having the boot screen support through eGPU is a huge deal! Can you provide more information such as cable connection whether there's anything display connected to iGPU? Currently my boot screen is through USB-C port to an ASUS USB-C portable monitor. The eGPU connects to a different monitor through DisplayPort cable.
Hey, I tested the following scenario:
Both the HDMI and USB-C video output on the Mac Mini was fully disconnected, the sole connection was through the eGPU's DisplayPort output. The Apple logo appears within a second of system powering up and the Boot Selector is available and working if I hold the Option button pressed during power up (which indicates that the change regarding pre-boot eGPU support was made on a firmware level on the Mini).
My Mac Mini's Boot ROM version (I don't have a non-Catalina beta 5 machine to compare):
1037.0.39.151.1 (iBridge: 17.16.10521.5.4,0)
@steve4332 I can confirm macOS Catalina 10.15 Beta 5 [19A526h] brought eGPU boot screen support! This was tested on RX 480 and RX Vega 56. Boot Selector worked great for me with automate-eGPU EFI too.
As seen in the photo below, 2018 Mac mini connected to VisionTek mini eGFX + RX 480 which connected to HP Z27q via DisplayPort. I use @goalque's automate-eGPU EFI so that what visible on the external monitor. No display was directly connected to the Mac mini.
This is great news.
Boot Screen support through eGPU remains working in 10.15 Dev Beta 6 (19A536g). It even worked in 5K with dual DisplayPort cables on the HP Z27q. The other headless Mac I have is 2013 Mac Pro. There are some changes during boot (colored horizontal lines) but no support like the 2018 Mac mini.
How early is this boot screen feature? Does it work with Startup Manager (hold option at startup)? Does it work with Clover / rEFInd? Such support requires a change to EFI. Is it a firmware update? Or is it a file in the EFI partition? Is it T2 chip related?
First post said it was a firmware update. A comparison of the firmware before and after the update might be interesting.
@joevt Following Dev Beta 5 on July 31st is when @steve4332 noticed this new Boot Screen support on his 2018 Mac mini with monitor through eGPU only. I tested mine and it worked by holding OPTION at boot. I can access the Startup Manager natively as well as automate-eGPU EFI. I have not tried rEFInd recently but don't see why it wouldn't work.
Which macOS version are you running on your 2018 Mac mini? I will check later today and post Boot ROM version if it's different than 1037.0.39.151.1 (iBridge: 17.16.10521.5.4,0) from 10.15 [19A526h]. I believe this feature is GPU-independent because the two AMD cards tested all worked (RX 480, RX Vega 56). I don't know how to check whether the Apple T2 chip provides this support or the EFI partition.
From my observation using the 2018 Mac mini iGPU, the Apple logo would immediately shows up once Power button is pushed. Startup Manager would then appear if OPTION key is held down. This behavior is on Apple T2-chip Macs only. Through the eGPU-connected monitor since 10.15 [19A526h], I do not see the immediate Apple logo. The screen would go straight to Startup Manager when OPTION key is held down at boot.
Update: The firmware was updated in Dev Beta 6. Boot ROM Version is now 1037.0.52.0.0 (iBridge: 17.16.10531.5.4,0).
I haven't tried Catalina, so I still have the older firmware:
Model Name: Mac mini
Model Identifier: Macmini8,1
Processor Name: Intel Core i3
Processor Speed: 3.6 GHz
Number of Processors: 1
Total Number of Cores: 4
L2 Cache (per Core): 256 KB
L3 Cache: 6 MB
Memory: 8 GB
Boot ROM Version: 220.218.104.22.168 (iBridge: 16.16.6568.0.0,0)
Hardware UUID: BEC81057-F233-538F-AB61-BA2ACC00880D
Did they change the Boot ROM version numbering scheme because mine says 220 instead of 1037
eGPU boot screen is not working for me in my Core i7 mac mini 2018 + Razer Core X + Radeon VII, I updated to the final Catalina release. When i power on the egpu and mac my monitor recognizes that there is output coming from the eGPU but it doesn't show anything. Is this a common issue?