Android 8.0 and higher mandate a minimum kernel version and kernel
configuration that is verified by the Vendor Test Suite (VTS) and over-the-air
(OTA) updates. Android device kernels must enable kernel .config
support and the option to read the kernel configuration at runtime through
procfs.
Kernel .config support
All device kernels must enable the entirety of android-base.cfg, which must include the following kernel-config options (or their kernel-version equivalent):
CONFIG_IKCONFIG=y CONFIG_IKCONFIG_PROC=y
Kernel version
For Android 9, the minimum Long Term Support (LTS) kernel version requirements are 4.4.107, 4.9.84, and 4.14.42.
- All system-on-chips (SoCs) productized in 2018 must launch with kernel 4.9.84 or newer.
- All other SoCs launching Android devices running Android 9 must use kernel 4.4.107 or higher.
- Device kernels based on 4.14 must include the 4.14.42 or higher LTS release.
- Regardless of launch date, all SoCs with device launches on Android 8.0 and higher remain subject to the kernel changes required to enable Treble.
- Older Android devices upgrading to Android 8.0 or higher can continue to use their original base kernel version.
For details on LTS kernels, see Long-term stable kernels and Android Common Kernels
Devicetree support
If the platform doesn't support Advanced Configuration and Power Interface (ACPI),
devicetree support in the kernel must be enabled and bootloaders must pass the
hardware description in the form of a devicetree to the kernel. The devicetree
must also be available for Android to read and be able to pass vendor- and
ODM-specific parameters to Android. CONFIG_OF is mandatory, along
with all other device- and subsystem-specific CONFIG_OF_* kernel
config options.
DebugFS
The implementation of the vendor interface shouldn't rely on
debugfs. It may be enabled, but VTS testing may be done with
debugfs unmounted.