Bianbu 4.0.7 UEFI on Milkv Jupiter 2: GRUB and HDMI Display Issues

Running a stock OS is fine until you want two of them. This week a community member (apcameron, Oct 10) installed Bianbu-LXQt-UEFI-K3 v4.0.7 on a Milkv Jupiter 2 with an explicit goal: multiboot between Bianbu and Gentoo via GRUB. Installation succeeded, but two annoyances appeared:

GRUB frequently fails to display on the HDMI monitor at boot
Sometimes there is no display at all after the system boots, forcing SSH access

The Setup Details That Matter

The board was powered and fed HDMI through a VENTION 6-in-1 USB-C dock (model THJ). On K3-class boards this is the first suspect: HDMI over a USB-C dock adds a DisplayPort-Alt-Mode hop and shares the USB-C power negotiation, and both GRUB and early boot are the most fragile windows for display init.

A Practical Checklist for This Class of Problem

Test HDMI directly on the board connector first. If the issue disappears, the dock DP alt-mode or power delivery negotiation is interfering - power the board separately and use the dock only for peripherals.
Try a different cable/monitor. Early GRUB output is often a plain framebuffer mode; monitors with slow EDID handling or docks that renegotiate on power events can miss it.
Keep SSH as your recovery path - which this reporter already did. Serial console (if exposed on your carrier board) is even better for UEFI/GRUB debugging.
For multiboot: make sure each distro UEFI entries point at its own ESP and kernel set; Bianbu 4.x UEFI images and their update-grub behavior have had known DTB-related pitfalls in earlier versions (see the v4.0.6 DTB-loss issue fixed after community reports).

If you are evaluating K3 boards for a Linux gateway + edge-AI build, this thread is also a good reminder of where the platform sits: the K3 (8x X100 + 60 TOPS AI cores, RVA23) now boots mainstream distros including Gentoo via UEFI, and the rough edges are at the firmware/display boundary rather than the core architecture.

Our related reading: the earlier community guides on enabling GRUB boot on Milkv Jupiter 2 (Bianbu 4.x) and running Gentoo on the K3 Pico-ITX.

Source: Bianbu-LXQt-UEFI-K3 on Milkv Jupiter 2 - Grub/HDMI issues (SpacemiT forum #1694)