Build and flash the MPTCP kernel

This section will guide you through build and deployment process of the MPTCP kernel.

Start with cloning the Linux kernel and ARM cross compilation toolchain from Github:

git clone https://github.com/gdetal/mptcp_nexus5.git
git clone https://github.com/yinquan529/platform-prebuilts-gcc-linux-x86-arm-arm-eabi-4.7.git

Now you are ready to build the kernel. First, set some environment variables and make the default config. Then you are ready to go:

cd mptcp_nexus5
export ARCH=arm SUBARCH=arm CROSS_COMPILE=../platform-prebuilts-gcc-linux-x86-arm-arm-eabi-4.7/bin/arm-eabi-
make hammerhead_defconfig
make -j8

Note: If you are using are more recent version of perl, you may encounter the following error:

Can't use 'defined(@array)' (Maybe you should just omit the defined()?) at kernel/timeconst.pl line 373.

If this happens, you have remove the if-statement in line 373 in the file kernel/timeconst.pl.

This will take a while, just be patient.

After the compilation is done, you have to make a bootable image:

abootimg -x <PATH_TO_ANDROID_FACTORY_IMG>/boot.img
sed -i 1d bootimg.cfg
abootimg --create mptcp_boot.img -f bootimg.cfg -k arch/arm/boot/zImage-dtb -r initrd.img

The final step, boot the created image:

adb reboot bootloader
sudo fastboot boot -c "console=ttyHSL0,115200,n8 androidboot.hardware=hammerhead user_debug=31 maxcpus=2 msm_watchdog_v2.enable=1" mptcp_boot.img

That’s it. You have build and deployed a MPTCP kernel for Android. Please note, that the change is only in-memory. After rebooting, the stock kernel will be used again and you have to reboot the MPTCP kernel. If you want to flash the kernel permanently, use the follwing command: fastboot flash boot mptcp_boot.img.

Proceed with the next step of the instructions.