Setup

Requirements

The following packages are needed on your build system (where extendrom will run):

• git
• curl
• python v3
• python v3 requests module (e.g: sudo python3 -m pip install requests)

Setup

create .repo/local_manifest/extendrom.xml and add:

<?xml version="1.0" encoding="UTF-8"?>
  <manifest>

     <!-- extendrom -->
     <remote name="sfX" fetch="https://github.com/sfX-Android/" />
     <project path="vendor/extendrom" name="android_vendor_extendrom" remote="sfX" revision="main" />

</manifest>

Now sync this repo with e.g: repo sync -j4 vendor/extendrom (this will happen automatically during a normal repo sync as well as long as you keep it in your local manifests).

activate and configure

add the following in your device/<vendor>/<model>/device.mk (or any other existing device mk file):

# Enable extendrom
$(call inherit-product, vendor/extendrom/config/common.mk)

add the following section to your device/<vendor>/<model>/vendorsetup.sh:

################## extendrom section ##################
# when using "EXTENDROM_PACKAGES" ensure you use quotes

export ENABLE_EXTENDROM=true

export <add-any-EXTENDROM-flag>=<EXTENDROM-flag-value>
# e.g.:
#export EXTENDROM_PACKAGES="F-Droid AuroraStore"

$PWD/vendor/extendrom/er.sh

Adding NEW(!) public GPG keys for verifying signatures

extendrom comes with a list of gpg keys which get auto-imported but sometimes you might need to extend that list.

extendrom will then verify signatures (if available) fully automatically for regular F-Droid packages. There is no need to do anything if you do not plan to use other repos for downloading packages.

If you plan to add non-standard repositories though:

You need to know the key id first which you can usually find beneath the package you want to add.
Another option is to find it by searching: gpg --keyserver pgp.mit.edu --search-keys f-droid.org
Of course there are other keyservers if pgp.mit.edu fails for you.

Once you got the id just add it to the variable GPG_KEYS in vendor/extendrom/er.sh (separate by a space from the others).

More information and the current F-Droid fingerprint can be verified here

building / changes in behavior

whenever you change something in device/<vendor>/<model>/vendorsetup.sh you HAVE TO apply these changes first.

The regular build process should always be like:

source build/envsetup.sh
lunch lineage_j5y17lte-user
mka otapackage
# (or mka eos when buildin /e/)

Note:
brunch or breakfast will work as well ofc