Building a Mobian Image for the Pixel 3a

Prerequisites

Cloning the repositories

Kernel: https://salsa.debian.org/erebion/sdm-670-linux

Mobian Recipes does not have the changes merged, as the kernel is not yet part of Mobian: https://salsa.debian.org/Mobian-team/mobian-recipes/-/merge_requests/113

Take my temporary fork of Mobian Recipes instead, for now: https://salsa.debian.org/erebion/mobian-recipes/-/tree/erebion/sargo-build?ref_type=heads

Make sure you check out my branch sargo-build which includes a couple of workarounds for changes which are not yet in the repos, but will be soon.

The fork will be maintained until there are official Mobian images for the Pixel 3a.

Compiling the Kernel

First cd to the kernel repo.

Then:

gbp pq import # import the patches to a patch-queue branch with the patches applied
DEB_HOST_ARCH=arm64 dpkg-buildpackage -a arm64 -us -uc -rfakeroot -b -Pcross,nocheck

Building the Image

Apparently you need to have android-sdk-libsparse-utils and, cryptsetup for encrypted images, installed, not sure what else might be required
First cd to the Mobian repo
Copy the kernel deb to devices/qcom/packages, so that it gets installed onta the image we are about to build.
Add your SSH authorized keys file to overlays/ssh/authorized_keys, important so you can log in later
Make sure the internet connection is stable, as the build fails if it cannot download all packages successfully.

Now build the image:

./build.sh -t qcom -s -u mobian -c -R myverysecretlukspassphrase | tee mobian-build.log # -s for SSH, which we need later

Do not use myverysecretlukspassphrase as your passphrase and replace it, obviously. :D

(If you replace mobian with your own username, you will have to use that one for SSH later, of course)

Wait. It takes a while.

Note: Your SSH Host Keys seemingly get generated while building the image, please don't give your image to anyone else. To Do: Verify whether those keys really end up in the image.

Flash to device:

fastboot --set-active --slot a
fastboot flash boot_a mobian-qcom-phosh-20240614.boot-sargo.img
fastboot flash userdata mobian-qcom-phosh-20240614.rootfs.img 
fastboot oem uart enable # currently does not seem to boot without, probably because the kernel config enables SSH for debugging right now
fastboot erase dtbo

Boot up the device. Connect it via USB.

Temporary manual changes

The steps are documented in README.md in this repo.

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