lk2nd
lk2nd is a bootloader for Qualcomm MSM devices, based on the CodeAurora Little Kernel fork. It provides an Android Fastboot interface on devices where the stock bootloader does not provide Fastboot (e.g. Samsung).
lk2nd does not replace the stock bootloader. It is packaged into an Android boot image and then loaded by the stock bootloader as a "secondary" bootloader. The real Android boot image is placed into the boot partition with 1 MB offset, and then loaded by lk2nd.
Supported SoCs
- MSM8952 (MSM8940)
- MSM8953 (SDM450,SDM625,SDM626)
- SDM632
Supported devices
- Motorola Moto G4 Play (harpia)
- Samsung Galaxy A3 (2015) - SM-A300FU
- Samsung Galaxy A5 (2015) - SM-A500FU
- Samsung Galaxy J5 (2016) - SM-J510FN
- Samsung Galaxy S4 Mini Value Edition - GT-I9195I
- Samsung Galaxy Tab A 8.0 LTE (2015) - SM-T357W
- Samsung Galaxy Tab A 9.7 WiFi (2015) - SM-T550
- Wileyfox Swift
- Samsung Galaxy A6+ (2018) - SM-A605FN
- Xiaomi Redmi 4X - santoni
- Xiaomi Redmi Note 4X Snapdragon - mido
- Xiaomi Redmi Note 5 / 5 Plus Snapdragon - vince
- Meizu M6 Note - m1721
- Motorola Moto G7 Power - ocean
- Xiaomi Mi A2 Lite - daisy
- Xiaomi Mi A1 - tissot
- XIaomi Mi A2 Lite - daisy
Installation
- Download
lk2nd.img
(as of now there's no build available so you'll need to build it yourself.) - Flash
lk2nd.img
using the stock flashing procedure:
- Fastboot:
fastboot flash boot lk2nd.img
- Samsung:
heimdall flash --BOOT lk2nd.img
Usage
lk2nd provides the standard Android fastboot protocol for flashing/booting Android boot images.
Press Volume Down
while booting to enter Fastboot mode.
Press Volume Up
while booting to boot into Recovery mode.
Note: If your stock bootloader uses the same key combinations, you need to wait a bit before pressing the volume keys. Usually, waiting until the screen turns on and/or the device vibrates should be enough to make the stock bootloader ignore the keys.
fastboot flash lk2nd lk2nd.img
can be used to update lk2nd directory from its
fastboot interface.
Note: fastboot flash boot boot.img
will flash the actual boot image with 1 MB offset
into the boot partition. This is done to avoid replacing lk2nd (since it is also booted from
the boot partition).
Other fastboot commands work normally.
Building
$ make TOOLCHAIN_PREFIX=arm-none-eabi- <SoC>-secondary
Requirements:
- ARM (32 bit) GCC tool chain
- Arch Linux:
arm-none-eabi-gcc
- Arch Linux:
- Device Tree Compiler
- Arch Linux:
dtc
- Arch Linux:
Replace TOOLCHAIN_PREFIX
with the path to your tool chain.
lk2nd.img
is built and placed into build-<SoC>-secondary/lk2nd.img
.
Porting
To other devices with supported Socs
- Add a simple device tree to
dts/
. You just needmodel
and theqcom,msm-id
/qcom,board-id
from downstream.
To other SoCs
- Cherry-pick changes
- Make some changes
- Add secondary project config
(TODO: Document this properly)
Contact
Ping minecrell
/Mis012
/uknown
/gavodavo
on #postmarketos-mainline
.