#RabbitHole: @okias@floss.social is doing a lot work to mainstream #sdm845 patches to the #linux kernel. During a meeting of Phosh.mobi e.V. members I learned that there seem to be not many testers for #Shift6mq #axolotl. I still had a broken Axolotl sitting on my desk…

• repaired the phone that originally had been bought as part of a #ShiftPhone8 deal
  • cleaning inside (residue from water contact)
  • new display (two lines of broken pixels)
  • new usb-c pcb (didn't charge, data broke during testing)
• learned about edl to recover if phone wouldn't boot to fastboot anymore (yes, really had that situation later )
• learned about the difference of fastboot and fastbootd mode
• learned about u-boot and the boot chain on the phone
• learned about dynamic partitions used in Android and how to use them from #linux
• learned about pmbootstrap
  • to build my own device images (mixture of existing axolotl and sdm845 to be compatible to the phone and the usage with u-boot and dynamic partitions)
  • changed pmbootstrap to build small (92M) boot image for boot_a/b partition
• tried to get more space for out of the phone for boot & root than provided by boot_a/b and system_a/b
  • resized userdata of Android
  • created two additional partitions for postmarketOS
• learned how to recover from kernel not booting without re-flashing
  • u-boot usb mass storage mode exports the mass storage of the phone over usb-c
  • phone connected to an aarch64 system (#Librem5 running #Mobian)
  • mounting encrypted partition, boot and what-else is needed
  • installing kernel packages via apk while in chroot on Librem5
• learned how to compile a kernel using ./envkernel.sh and pmbootstrap

Now I'm quite sure I can recover from any failure I will encounter while testing sdm845 kernels and I have the following setup on my Shift6mq:

• ShiftOS-L with small userdata partition in slot_b
  • applications for demoing the phone installed
  • work profile to contain closed source applications
• postmarketOS edge installed on partitions behind userdata
  • u-boot on rescue_a
  • 1GB pmOS_boot
  • 60GB pmOS_root
  • applications for demoing
  • multi-user: my testing user, demo user
  • everything except cameras work
• dual-boot possible on-the-go: enter fastboot (by holding vol-up at start), change slot, reboot

I put my notes on the postmarketOS wiki.

I started two merge requests:

• support audio configuration when started through u-boot in alsa
• add support for booting using u-boot and dynamic partitions to axolotl

I'll carry the phone at #clt2026 - Chemnitzer Linux Tage 2026 - on saturday 28th this month. I'll mostly be around the "Linux on Mobile" booth.

On my testing #Librem5 running #Mobian I had obviously installed a workaround to get echo cancellation for calls by using #pulseaudio for audio. I had forgotten about it and after some update or hardware tinkering sound just didn't work anymore.

I found out that I knew not much about sound and while trying to understand how it is supposed to work I wrote some of my findings on the Librem5 community wiki.

I'd be thankful for corrections and additions to be able to move the page soon out of the work in progress section.

@etam@im-in.space @craftyguy@freeradical.zone

That really looks interesting!

In PureOS/Debian it will be available in Crimson/Bookworm. I didn't find it in Byzantium/Bookworm.

It might already be an option for #Mobian and #PostmarketOS.