# LetuxOS Kernel Project #
This is a Subproject of the [GTA04][] and [Openmoko Beagle Hybrid][] activities.

[GTA04]: ../gta04-main
[Openmoko Beagle Hybrid]: ../ombeagle

It provides fully functional Linux kernels for the [Openmoko Beagle Hybrid][1] and the [GTA04][] as well as for devices which are currently being developed (e.g. Neo900, Pyra-Handheld).

[1]: ../ombeagle

# Versions

NOTEs:

* ARM (armel + armhf) supports OMAP3/4/5, iMX.6 and RasPi
* ARM-LPAE (armel + armhf) version is useful for OMAP5 only!
* ARM64 (arm64) is for PinePhone (and future 64 bit ARM devices)
* MIPS (mipsel) is for JZ4730 (Mipsbook/Alpha 400) and JZ4780 (CI20)
* RISCV64 (riscv64) is intended for StarFive JH7110 based boards

Please refer to about the status of support for each feature/device.

Update versions table

Variant	Sources	Changes	Date	Binaries	description
rc (latest/alpha):	7.0-rc3	changes	2026-03-09	arm arm64 x86 L400(mips) arm+lpae mips replicant-arm mips riscv	For alpha test: develop and test new features
stable (beta):	6.19.3	changes	2026-02-26	arm arm64 x86 L400(mips) arm+lpae mips replicant-arm riscv	multi-platform, mature enough for daily use supports OpenPandora, GTA04, Letux Cortex 8, BeagleBoard, BeagleBone, PocketBeagle, PandaBoard, OMAP5EVM, Pyra, Udoo neo, RasPi 3B+, CI20, PinePhone, Kobo/Tolino, SAMA5, LX16
longterm (beta):	6.18.16	changes	2026-03-10	arm arm64 x86 L400(mips) arm+lpae mips replicant-arm riscv	multi-platform, mature enough for daily use supports OpenPandora, GTA04, Letux Cortex 8, BeagleBoard, BeagleBone, PocketBeagle, PandaBoard, OMAP5EVM, Pyra, Udoo neo, RasPi 3B+, CI20, PinePhone, Kobo/Tolino, SAMA5, LX16
longterm (beta):	6.12.76	changes	2026-03-10	arm arm64 x86 L400(mips) arm+lpae mips replicant-arm	multi-platform, mature enough for daily use supports OpenPandora, GTA04, Letux Cortex 8, BeagleBoard, BeagleBone, PocketBeagle, PandaBoard, OMAP5EVM, Pyra, Udoo neo, RasPi 3B+, CI20, PinePhone, Kobo/Tolino, SAMA5, LX16
longterm master:	6.6.129	changes	2026-03-10	arm arm64 x86 L400(mips) arm+lpae mips replicant-arm	multi-platform, mature enough for daily use supports OpenPandora, GTA04, Letux Cortex 8, BeagleBoard, BeagleBone, PocketBeagle, PandaBoard, OMAP5EVM, Pyra, Udoo neo, RasPi 3B+, CI20, PinePhone, Kobo/Tolino, SAMA5, LX16
longterm (beta):	6.1.166	changes	2026-03-11	arm arm64 x86 L400(mips) arm+lpae mips replicant-arm	multi-platform, mature enough for daily use supports OpenPandora, GTA04, Letux Cortex 8, BeagleBoard, BeagleBone, PocketBeagle, PandaBoard, OMAP5EVM, Pyra, Udoo neo, RasPi 3B+, CI20, PinePhone, Kobo/Tolino, SAMA5
longterm (beta):	5.15.202	changes	2026-03-11	arm arm64 x86 L400(mips) arm+lpae mips replicant-arm	multi-platform, mature enough for daily use supports OpenPandora, GTA04, Letux Cortex 8, BeagleBoard, BeagleBone, PocketBeagle, PandaBoard, OMAP5EVM, Pyra, Udoo neo, RasPi 3B+, CI20, PinePhone, Kobo/Tolino
longterm (beta):	5.10.252	changes	2026-03-11	arm arm64 x86 L400(mips) arm+lpae mips replicant-arm	multi-platform, mature enough for daily use supports OpenPandora, GTA04, Letux Cortex 8, BeagleBoard, BeagleBone, PocketBeagle, PandaBoard, OMAP5EVM, Pyra, Udoo neo, RasPi 3B+, CI20, PinePhone, Kobo/Tolino
rolling (stable):	rolling-stable	changes	2026-03-12	arm arm64 CI20(mips) x86 L400(mips) arm+lpae LX16(mips) LX20(mips) mips replicant-arm replicant-replicant-arm riscv	multi-platform, mature enough for daily use supports OpenPandora, GTA04, Letux Cortex 8, BeagleBoard, BeagleBone, PocketBeagle, PandaBoard, OMAP5EVM, Pyra, Udoo neo, RasPi 3B+, CI20, PinePhone, Kobo/Tolino, SAMA5, LX16
rolling (lts):	rolling-lts	changes	2026-03-12	arm arm64 CI20(mips) x86 L400(mips) arm+lpae LX16(mips) mips replicant-arm replicant-replicant-arm	multi-platform, mature enough for daily use supports OpenPandora, GTA04, Letux Cortex 8, BeagleBoard, BeagleBone, PocketBeagle, PandaBoard, OMAP5EVM, Pyra, Udoo neo, RasPi 3B+, CI20, PinePhone, Kobo/Tolino, SAMA5, LX16
android:	4.9.4-replicant 4.10.5-replicant 4.17.3-replicant 4.19-replicant 4.14-replicant			GTA04	includes patches so that we can build kernels for Replicant (GTA04 and source code only)
longerm [EOL]:	3.12.37			GTA04	GTA04 (except A5) feature complete (incl. camera), but lacks some power management
longerm [EOL]:	3.12-replicant			GTA04	GTA04 (except A5) kernel modified/configured differently to better support Replicant
longerm [EOL]:	3.7-neil-plus			GTA04	GTA04 (except A5): good power management, lacks some features (e.g. camera)
longerm [EOL]:	2.6.30-rc4			jz4730	Letux 400 and other Mini-Books

# The Mainline-Plus Kernel concept (tracking linus/master = mainline)

See the [branches][master] which are based on the mainline [linus/master][linus] kernel.

Basically there is a "stable" master branch and rolling release candidate branches and feature development ("work in progress") branches. Feature branches are patch set sitting on top of "letux-base".
The "latest" branch is a copy of the latest "stable master" branch.

Every time Linus publishes a new release candidate (typically once per week on average), we update the letux-base branch and rebase all our new features. For example, the "letux-base" can currently be v4.19-rc2. One week later, we will have v4.19-rc3.

Then we merge all feature branches on top of letux-base and this creates e.g. letux-4.19-rc3. Note, that there is no linear history from letux-4.19-rc2 to letux-4.19-rc3 because there are rebases involved.

We also maintain long-term and stable kernels as defined by . Every now and then, we merge in the latest stable release from kernel.org and sometimes backport important changes from the rolling release candidates.

## supported devices (through different device tree files)

* BeagleBoard C, BeagleBoard XM
* BeagleBoard (C/XM) with [Openmoko Beagle Hybrid][] expansion board
* [GTA04A3, GTA04A4, GTA04A5][GTA04] (Letux 2804)
* GTA04b2 (Letux 3704)
* GTA04b3 (Letux 7004)
* planned: GTA04b7 (Neo900)
* PandaBoard ES
* OMAP5432EVM
* OMAP5432EVM + Pyra development boards
* BeagleBone
* PocketBeagle
* Letux Cortex 8 (similar to PocketBeagle)
* Letux Cortex 15 (Pyra CPU-Board stand-alone)
* Pyra-Handheld
* Letux Cortex 15 EVAL (Evaluation Board for Letux Cortex 15)
* Pyra Phone (planned)
* Udoo Neo
* CI20 creator
* Alpha 400 (only partially working)
* RaspBerry Pi 3B+
* RaspBerry Pi Zero
* PinePhone
* Odroid M1
* SAMA5D2 Explained
* Letux X16
* Letux X20
* PocketBeagleY-AI
* PocketBeagle 2
* Pine64 Star64

Please note that U-Boot is responsible for loading the correct device tree file.

For a list of features supported on each device, please see .

## Philosophy
* follows the latest kernel releases and includes security patches
* based on the latest (release candidates)
* add the latest Linux features
* have a rolling letux-base
* aim at full support of the hardware by drivers that are not (yet) in mainline ("plus")
* provide drivers for as many hardware features as possible in a clean way
* can be used in daily life
* our patches are pushed to go upstream so that the 'plus' part gets smaller and smaller step by step
* have older long-term kernels (maybe missing some features)

## Features / Maturity
### GTA04 devices

The branches tracking linus/master currently don't support well (please refer to [issues][Issues]):

* WiFi power management
* Torch/Flash
* Camera
* IrDA
* DSP
* 3D Accelerator (PVR/SGX)

### BeagleBoards
it works on the BeagleBoard XM with OpenMoko-BeagleHybrid display expander and on a BeagleBoard C w/o.

### PandaBoard
it appears that everything works (incl. audio)

### OMAP5432EVM/Pyra/PyraPhone
not working: AESS based audio, 3D Accelerator (PVR/SGX)

## Contributions
Please download, test and patch the kernel tree. Please submit patches against the latest version (e.g. 4.5-rc2) and mail them to the letux-kernel mailing list. Thank you!

If you have problems with git, please refer to [[Contribute]].

## Reporting Issues
Please report all kernel issues through the "Issues" tab on this project.

## Mailing List
There is a public mailing list dedicated to the Letux-Kernel:

# Donations

We actively work on the kernel and upstreaming patches, but this needs some funding for the developers. If you want to donate, you are welcome!

# Installation
Building the kernel:

git clone http://git.goldelico.com/letux-kernel.git
cd letux-kernel
git checkout latest
make ARCH=arm CROSS_COMPILE=arm-none-linux-gnueabi- letux_defconfig uImage LOADADDR=0x80008000 dtbs INSTALL_MOD_PATH=/tmp/kernel-modules-$$ modules modules_install
cp arch/arm/boot/uImage modules arch/arm/boot/dts/omap*.dtb /mount/sdcard/boot/

You can also use git://git.goldelico.com/letux-kernel.git but this is a little less reliable on weak connections.

There is also letux_lpae_defconfig which enables LPAE and disables OMAP3+4 support.

Please refer to the [GTA04 Rootfs][rootfs] for installation instructions of a complete distribution (bootloader, kernel, rootfs, LXDE GUI).

[rootfs]: ../gta04-rootfs

# Controlling Hardware Features from User Space

You want to control the hardware features from user space. How this is done can be seen in the [Documentation][] and [[Devices-Overview]] .

[Documentation]: doc

[master]: http://git.goldelico.com/?p=letux-kernel.git;a=heads
[linus]: https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/log/