dd'ing an "install --fde" image for valve-jupiter/steam deck to emmc will lead to the boot screen not finding the boot partition

Describe your issue

dd'ing an "install --fde" image for valve-jupiter/steam deck to the internal emmc will lead to the boot screen not finding the boot partition. This happens despite when putting the same image on an usb stick instead, the Steam Deck boots from it just fine with the FDE unlock working without any issues.

There doesn't seem to be any obvious issues with the partition ids, as can be seen from these photos that show the boot config as found on the EMMC after the dd completed:

What's the expected behaviour?

The boot partition is found.

What's the current behaviour?

Before unl0kr even allows entering any password, there's a "Waiting for partition..." followed by an "ERROR: Boot partition not found". It's not possible to progress from there. This is only when running the image from the EMMC with no other disk attached, when instead booting from the usb stick it works fine.

How to reproduce your issue?

1. Create a valve-jupiter imag with --fde and dd it to some usb stick, then also dd it to the steam deck's EMMC.

2. Boot from the EMMC with no disk attached. This is what you'll see:

3. Then attach the usb stick with the same image while the Steam Deck is shut off, use "volume down" + "power button" to get into the boot menu, and boot the same image from the usb stick. There shouldn't be an error and FDE unlock will work, and you should be booting into a working system instead. (So the image isn't inherently unbootable.)

What device are you using?

Steam Deck emmc (no SSD, no SD card attached)

On what postmarketOS version did you encounter the issue?

• edge (master branch)

• v24.06

• v23.12 (supported until 2024-07-16)

• I confirm that the issue still is present after running sudo apk upgrade -a

On what environment did you encounter the issue?

Environments

• GNOME Shell on Mobile
• Phosh
• Plasma Mobile
• Sxmo (Wayland/Sway) Please post the output of sxmo_version.sh
• Other: KDE desktop

How did you get postmarketOS image?

• from https://images.postmarketos.org
• I built it using pmbootstrap
• It was preinstalled on my device

What's the build date of the image? (in yyyy-mm-dd format)

today

Additional information