Unfortunately, early firmware versions on MSM8916 (used together with
Android 4.4) are not capable of booting aarch64 kernels. MSM8916 was
Qualcomm's first 64-bit capable CPU, and back when it was introduced
Android did not even support aarch64 yet. So the aarch64 capable
hardware was usually used together with armv7 binaries.
To make things worse, this firmware is also signed (usually per-device),
making it (currently) impossible to update it without help from the manufacturer.
This means that we are currently unable to run mainline on devices
that never received an update to Android 5.0
(e.g. the Samsung Galaxy S4 Mini Value Edition).
One way to circumvent this limitation is to build mainline for armv7.
This works surprisingly well with some additional fixes.
Devices with this firmware limitation are still unable to use aarch64
binaries, but at least we can run mainline on them!
