Replicant » Upstreaming patches

h1. Mainline

h2. Benefits of using mainline Linux

Currently, Replicant uses device specific Hardware Abstraction Layers, because device manufacturers implemented non-standard kernel interfaces. However, Android works with mainline kernels and supports plug-n-play hardware nowadays, so it makes sense to have generic Hardware Abstraction Layers for the standard interfaces of the Linux kernel (ALSA, V4L2, etc).

Benefits:

* It would allow supporting external WiFi dongles such as the ones supported by the ath9k_htc driver and free firmwares without the need for a specific application or configuration.

* It would make devices last longer by alleviating the device specific maintenance burden: If LineageOS stops supporting a Replicant supported device, Replicant would need to maintain it by its own. This would require a lot of work, unless the device is already supported the mainline Linux kernel and generic hardware abstractions layers. This would enable Replicant to support devices that are not currently supported by LineageOS.

* It would enable the support for devices that are or will be added to mainline Linux.

h2. Requirements

* Adding a generic WiFi HAL for external dongles only requires a device that is supported by Replicant, and that can provide enough power for the dongle.

* For the other standard interfaces (like ASLA, etc) a device running a mainline Linux Kenrel with as few patches as possible is required.

h2. Devices

It is best to use a device that requires the least amount of work to be functional under Replicant.

More precisely we want to minimize:

* The work needed to have the device usable with mainline Linux.

* The work porting or writing Android hardware abstractions layers.

To achieve that we can choose a device that:

* requires no or very minimal work to be fully supported by Linux.

* have less hardware features (so we don't need to support them in Linux and in the HALs).

* is easy to buy, so the work can be shared among multiple people.

It is also a good idea to keep one image per device, as trying to make a single image that

would work on all ARM device supported by mainline Linux is complicated: Even ARM GNU/Linux

distributions still have some issues with that.

h3. Smartphones and tablets with a free software bootloader and work in progress mainline Linux support

h3. Replicant supported Samsung Exynos devices

h3. Allwinner devices

h2. See also

* [[Google Summer of Code 2018]]