lk2nd

lk2nd is a bootloader for Qualcomm MSM devices (at the moment only MSM8916 and MSM8939), 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).

On MSM8916 it is also used for some quirks for mainline devices, e.g. to set a proper WiFi/BT MAC address in the device tree.

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 512 KiB offset, and then loaded by lk2nd.

Supported SoCs

msm8916-secondary: APQ8016, MSM8216, MSM8916, MSM8929, MSM8939
msm8974-secondary: MSM8974
msm8226-secondary: APQ8026, MSM8226, MSM8926

See Chipsets page on the EFIDroid wiki for an exact mapping of LK targets to SoCs.

Supported devices

msm8916-secondary

Alcatel OneTouch Idol 3 (4.7) - 6039*
Alcatel OneTouch Idol 3 (5.5) - 6045*
Asus Zenfone 2 Laser (720p) - Z00L
Asus Zenfone 2 Laser (1080p) - Z00T
Asus Zenfone Max ZC550KL (2016) - Z010D
BQ Aquaris M5 - piccolo (use lk2nd-msm8916-appended-dtb.img)
BQ Aquaris X5 - paella, picmt
DragonBoard 410c - apq8016-sbc
HTC One M8s - m8qlul (quirky - see comment in dts/msm8916/msm8939-htc-m8qlul.dts)
Huawei Ascend G7 - G7-L01
Huawei Honor 5X - kiwi
Huawei Y635 - Y635-L01 (quirky - see comment in dts/msm8916/msm8916-huawei-y635-l01.dts)
Lenovo A6000
Lenovo A6010
Lenovo PHAB Plus - PB1-770M, PB1-770N
LG K10 (m216) - K420
LG Leon LTE (c50) - H340, H342, H343, H345, MS345, etc
LYF Wind 1 - ls5010
Marshall London
Motorola Moto E (2015) - surnia
Motorola Moto G (2015) - osprey
Motorola Moto G4 Play - harpia
Samsung Galaxy A3 (2015) - SM-A300F, SM-A300FU
Samsung Galaxy A5 (2015) - SM-A500F, SM-A500FU, SM-A500YZ
Samsung Galaxy Core Max - SM-G5108Q (quirky - see comment in dts/msm8916/msm8916-samsung-r08.dts)
Samsung Galaxy Core Prime LTE - SM-G360F
Samsung Galaxy Grand Prime - SM-G530W
Samsung Galaxy J3 (2016) - SM-J3109
Samsung Galaxy J3 Pro - SM-J3110, SM-J3119
Samsung Galaxy J5 (2015) - SM-J5008, SM-J500F, SM-J500FN, SM-J500H
Samsung Galaxy J5 (2016) - SM-J5108, SM-J510F, SM-J510FN
Samsung Galaxy J7 (2015) - SM-J7008, SM-J700P
Samsung Galaxy On7 (2015) - SM-G6000
Samsung Galaxy S4 Mini Value Edition - GT-I9195I
Samsung Galaxy Tab 4 10.1 (2015) - SM-T533
Samsung Galaxy Tab A 8.0 LTE (2015) - SM-T355Y, SM-T357W
Samsung Galaxy Tab A 9.7 WiFi (2015) - SM-T550
Vodafone Smart prime 6
Wileyfox Swift - crackling
Xiaomi Mi 4i - ferrari
Xiaomi Redmi 2 - wt86047, wt88047

msm8974-secondary

LG G3 - D855
Samsung Galaxy S5 - SM-G900F

msm8226-secondary

LG G Watch R - lenok

Installation

Download lk2nd.img (available in Releases)
Flash lk2nd.img using the stock flashing procedure:

Fastboot: fastboot flash boot lk2nd.img
Samsung: heimdall flash --BOOT lk2nd.img

If you get fastboot: error: Couldn't parse partition size '0x' try one of the following workarounds:

fastboot flash:raw boot lk2nd.img
fastboot boot lk2nd.img, then fastboot flash lk2nd 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 directly from its fastboot interface.

Note: fastboot flash boot boot.img will flash the actual boot image with 512 KiB 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.

Troubleshooting

If the device shows up via fastboot you can get a log file from lk2nd using fastboot oem lk_log && fastboot get_staged <output-file>, where <output-file> is either some text file to write to (e.g. output.txt) or /dev/stdout to write the log to standard output.

Building

Check Supported SoCs for the make target you should use below. (It depends on the SoC of your device.)

$ make TOOLCHAIN_PREFIX=arm-none-eabi- msmXXXX-secondary

Requirements:

ARM (32 bit) GCC tool chain
- Arch Linux: arm-none-eabi-gcc
Device Tree Compiler
- Arch Linux: dtc

Replace TOOLCHAIN_PREFIX with the path to your tool chain. lk2nd.img is built and placed into build-msm8916-secondary/lk2nd.img.

Porting

To other MSM8916/8974 devices

Add a simple device tree to dts/. You just need model and the qcom,msm-id/qcom,board-id from downstream.

To other SoCs

Qualcomm maintains separate branches for various groups of SoCs. The branches can be seen on the Chipsets page on the EFIDroid wiki. This version of lk2nd is based on the LA.BR branch for MSM8916. There is a fork for MSM8953 based on the LA.UM branch.

The bootloader will work best when you use the correct branch for your device. Older platforms are usually kept around by Qualcomm but barely tested and may not work, or not even compile.

However, if make files for your SoC are present in this version or the MSM8953 fork you can try to enable it and see if it works well enough for you. Otherwise you would need to go through the Git history and pick the relevant commits to another branch from https://source.codeaurora.org/quic/la/kernel/lk/.

To enable support for a SoC that is already present in this repository:

Create a new project/<target>-secondary.mk which looks like the others.
Try to compile it and fix all the compile errors.
Try to run it and hope that it works.

Good luck!

Contact

Ping minecrell/Mis012 on #postmarketos-mainline.

fynngodau/lk2nd