Ubuntu/Kubuntu boots only once, then hangs with blinking cursor (MacBook Pro 2019, T2)

[blaugrau90]

Description

Hi,

I'm trying to set up a dual boot (macOS + Ubuntu/Kubuntu) on a MacBook Pro 2019 with the T2 chip using this project.

The installation of Ubuntu/Kubuntu completes successfully, and the system boots normally exactly once — immediately after installation.

However, after the first reboot, Ubuntu/Kubuntu no longer boots. It briefly shows the distribution logo, then gets stuck on a black screen with a blinking cursor indefinitely.

Hardware

• Device: MacBook Pro 2019 (T2 chip)
• macOS: macOS Tahoe
• Secure Boot: Disabled

Linux Versions Tested

• Ubuntu 24.04
• Ubuntu 25.10
• Kubuntu (same behavior)

Installation Details

• Installation completed without errors
• No disk encryption
• Manual partitioning (“Something else”)
• Bootloader installed on the main disk (selected EFI and mounted it to /boot/efi)
• No additional t2linux kernel packages were installed
• Tested both Apple boot picker and rEFInd (same result)

Boot Behavior

1. Installation completes successfully

2. First boot works normally

3. After reboot:

   • Ubuntu entry still appears in boot picker
   • Distribution logo appears
   • Then black screen with blinking cursor indefinitely
   • No GRUB menu visible (Shift/ESC has no effect)

Questions

• Is this a known issue with T2 Macs?
• Could this be related to missing t2linux kernel packages or firmware?
• Is there a recommended installation procedure to ensure Ubuntu/Kubuntu boots reliably on macOS Tahoe?

Any guidance would be greatly appreciated.

Thank you.

[AdityaGarg8]

I am seeing this issue for the first time. Are you using the official ISO from Ubuntu or the one from this repo?

[blaugrau90]

I used the ISOs from the repo. I haven’t tried the official iso yet.

[AdityaGarg8]

Could you check if the issue is with official ISOs as well?

[blaugrau90]

Ubuntu/Kubuntu on MacBook Pro T2 with dual GPUs hangs after first boot – requires hybrid graphics configuration

Hi,

I ran into a problem installing Kubuntu on a MacBook Pro 2019 with a T2 chip and dual GPUs (integrated + AMD discrete GPU) using this project.

The installation completes successfully with the t2linux kernel (6.18.5‑1‑t2‑questing) and the system boots fine at first. However, after rebooting without kernel parameters, the system hangs with only a blinking cursor and does not boot further.

I initially resolved this by blacklisting the AMD GPU driver (modprobe.blacklist=amdgpu), which allowed a stable boot using the integrated GPU. But this prevented use of the AMD card.

Later I found the relevant documentation on the t2linux Wiki under Hybrid Graphics, which explains that Linux on Macs with hybrid graphics requires a configuration change to select the iGPU by default and avoid boot failures caused by the dGPU initialization. Specifically:

You can enable the iGPU at boot by creating a file /etc/modprobe.d/apple-gmux.conf with:

options apple-gmux force_igd=y

This forces the integrated GPU and allows the discrete AMD GPU to remain inactive initially, preventing the hang. ([wiki.t2linux.org][1])

This solves the blinking cursor boot hang without requiring kernel boot parameters and allows the system to boot reliably.

Recommendation

It would be very helpful to include a note in the installation guide for this repo that on Macs with two GPUs, such as many T2 MacBook Pro models with AMD dGPUs, this additional configuration is required for stable boot. A reference to the hybrid graphics page on the t2linux Wiki would also be useful:

https://wiki.t2linux.org/guides/hybrid-graphics/ ([wiki.t2linux.org][1])

Thank you!

[lemmyg]

Did you try adding the Dynamic Power Management level rule ?
https://wiki.t2linux.org/guides/hybrid-graphics/