# Kernel Toolchains 
## AOSP (GCC & Clang ) and Snapdragon Clang
--------
How to compile android kernel? Detailed Instructions [**Here**](https://forum.xda-developers.com/t/reference-how-to-compile-an-android-kernel.3627297/).  
Install latest version of Make from [**Here**](https://ftp.gnu.org/gnu/make).  
Instructions here are only for Linux OS machines, don't get messed in Windows unless you know how to use properly.
--------
Getting Started
==================================================
--------
### How to use these toolchains for compiling android Kernels ?
--------
0. Clone this toolchain repo in tools folder
```bash
$ git clone --depth=1 https://github.com/pkm774/android-kernel-tools tools
```
1. Install required packages, for Debian distros :
```bash
$ sudo apt-get update && sudo apt-get upgrade -y
$ sudo apt-get install gcc-aarch64-linux-gnu -y
```
-> Now compile using AOSP clang or Snapdragon clang.

## For using AOSP clang:
2. Set path for the toolchains.

```bash
$	PATH="tools/gcc/linux-x86/aarch64/aarch64-linux-android-4.9/bin:$PATH"
$	PATH="tools/gcc/linux-x86/arm/arm-linux-androideabi-4.9/bin:$PATH"
$	PATH="tools/clang/host/linux-x86/clang-r428724/bin:$PATH"
$	export LD_LIBRARY_PATH="tools/clang/host/linux-x86/clang-r428724/lib64:$LD_LIBRARY_PATH"
```
3. Export required flags

```bash
$	export ARCH=arm64
$	export SUBARCH=ARM64
$	export CLANG_TRIPLE=aarch64-linux-gnu-
$	export CROSS_COMPILE=aarch64-linux-android-
$	export CROSS_COMPILE_ARM32=arm-linux-androideabi-
```
>> ARCH & SUBARCH according to your device.

4. Use these command for compiling with **AOSP clang**.

```bash
$ make \
	O=out \
	clean \
	mrproper \
	CC=clang \
	AR=llvm-ar \
	NM=llvm-nm \
	OBJCOPY=llvm-objcopy \
	OBJDUMP=llvm-objdump \
	READELF=llvm-readelf \
	OBJSIZE=llvm-size \
	STRIP=llvm-strip \
	HOSTCC=clang \
	HOSTCXX=clang++ \
	${DEVICE}_defconfig
  
$ make \
	O=out \
	CC=clang \
	AR=llvm-ar \
	NM=llvm-nm \
	OBJCOPY=llvm-objcopy \
	OBJDUMP=llvm-objdump \
	READELF=llvm-readelf \
	OBJSIZE=llvm-size \
	STRIP=llvm-strip \
	HOSTCC=clang \
	HOSTCXX=clang++ \
	-j$(nproc --all)
```
>> {DEVICE}_defconfig is the kernel config file used to compile kernel. Kernel binaries will be produced in **out** directory.
## For using Snapdragon clang:

2. Set path for the toolchain.

```bash
$	PATH="$TOP/tools/sdclang/linux-x86_64/bin:$PATH"
```
3. Export required flags.

```bash
$	export ARCH=arm64
$	export SUBARCH=ARM64
$	export CROSS_COMPILE=aarch64-linux-gnu-
$	export CROSS_COMPILE_ARM32=arm-linux-gnueabi-
```
>> ARCH & SUBARCH according to your device.

4. Use these command for compiling with **Snapdragon clang**.

```bash
$ make \
	O=out \
	clean \
	mrproper \    
	CC=clang \
	${DEVICE}_defconfig
    
$ make \
	O=out \    
	CC=clang \
	-j$(nproc --all)
```
>> {DEVICE}_defconfig is the kernel config file used to compile kernel. Kernel binaries will be produced in **out** directory.
--------
#### # It will be easy to compile kernel with a bash script. Make a bash script in kernel folder and set toolchain path according to your folders.  
AOSP clang is taken from : [**Android Open Source Project**](https://source.android.com).  
Snapdragon clang is taken from : [**developer.qualcomm.com**](https://developer.qualcomm.com/forums/software/snapdragon-llvm-compiler-android).  
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