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[GUIDE] Kernel Build Guide

This is a basic kernel build guide, to help those that keep coming into IRC asking for help.
If you follow this, you should have a working kernel that will work with ext4 or RFS.
NOTE::I wrote this at 1am, when Im kinda falling asleep, so there might be errors. Please let me know, and Ill fix it up
What you need:
A Linux system, with about 2gb free (This is written for 32bit systems, 64bit will need a compatible toolchain)
Development libraries
The kernel source
An ARM toolchain
An initramfs from an existing kernel
Downloads
EB13 source - search for D700 under mobile phone
Code Sourcery 2009q3 ARM toolchain
Daemon's Ext4/RFS Initramfs
Steps:
Set up the build environment
The first thing you need to do is set up the build environment.
For Ubuntu or other Debian-based system, you need the build-essential package and libncurses.
You can install this by running this command:
Code:
sudo apt-get install build-essential libncurses5-dev
If your not running Ubuntu/Debian, the packages are gcc, g++, libc-dev, and make.
Next, your going to need a directory for all your kernel build. You can't have spaces in any folder name. Im going to use /home/tortel/build/ for the rest of this guide.
Now you need to extract the kernel source to your directory. In the Samsung source file, its SPH-D700_kernel.tar
Next, extract the ARM toolchain into your build directory.
Last, extract your initramfs into the directory.
After this, your build directory should contain 4 things:
Code:
arm-2009q3/
eb13init/
Kernel/
build.sh
For this guide, Im not going to use the build.sh. If you want to, you'll need to configure that yourself.
Configure your kernel
Now the fun begins.
You need to edit the Kernel/Makefile file, and change line 184 to match where your toolchain is. My line 184:
Code:
CROSS_COMPILE ?= /home/tortel/build/arm2009q3/bin/arm-none-linux-gnueabi-
Now you need to configure the kernel.
The kernel configuration file is called .config, which is hidden by default (Ctrl+H shows hidden files in GNOME). You need to set lines 81-91, so it uses your initramfs. My lines:
Code:
CONFIG_BLK_DEV_INITRD=y
CONFIG_INITRAMFS_SOURCE="/home/tortel/kernel/eb13init/"
CONFIG_INITRAMFS_ROOT_UID=0
CONFIG_INITRAMFS_ROOT_GID=0
CONFIG_RD_GZIP=y
CONFIG_RD_BZIP2=y
CONFIG_RD_LZMA=y
# CONFIG_INITRAMFS_COMPRESSION_NONE is not set
CONFIG_INITRAMFS_COMPRESSION_GZIP=y
# CONFIG_INITRAMFS_COMPRESSION_BZIP2 is not set
# CONFIG_INITRAMFS_COMPRESSION_LZMA is not set
This will build your initramfs into the kernel image.
Now, your set to build.
Build the kernel
This is the easy part. Open a terminal, cd to build/Kernel and run make.
The commands:
Code:
cd build/Kernel/
make
If you have more than one core, you should add -j {1+ # of CPU cores} to make so it finishes faster. It only takes about 5min on my 2ghz C2D laptop.
Make it flashable!
Congrats, its built!
The file you want is Kernel/arch/arm/boot/zImage in your kernel source directory. After make finishes, run:
Code:
cp arch/arm/boot/zImage ..
This copies your kernel image file into your main build directory. Now, you need to put it into a flashable zip. To make it easy, here. Just throw the zImage into the root of that zip, put it on your SD card, and flash it.

Might want later
Advanced config stuff to come

Might want this too

Thank you for this, I'm glad too see this and others who have contributed great guides like this.
sent from "The Other Woman"

I was one of those people who kept bothering lol. I learned how to compile a kernal in two day though, now im on my way making a OC/UV Voodoo color kernal (coming soon) :]
Thanks alot

globalninja said:
I was one of those people who kept bothering lol. I learned how to compile a kernal in two day though, now im on my way making a OC/UV Voodoo color kernal (coming soon) :]
Thanks alot
Click to expand...
Click to collapse
what should I look into for making the changes necessary for an overclocking kernel?

Thanks for this helpful thread, and I had a question previously, that someone pm'ed me for. OP, please remove this reply if you feel inclined to. I had a question about the initramfs because my computer was having problems loading the page for the link.

Hey guys, kindof a noob to this.
How can I get an initramfs for DI18? Ideally, I could just use the one in the stock ROM unmodified, but I have no idea how to obtain it.
I figured it out! Used the scripts here to extract it from zImage:
http://forum.xda-developers.com/showthread.php?t=901152

[GUIDE] How to Build and Package a Kernel [D2]

This thread aims to be a comprehensive guide to building and packaging kernels for US Variant Samsung Galaxy SIIIs
In my opinion, a kernel is a great way to get into building things for your device and its pretty easy to do too.
Intro
What is a kernel?
http://en.wikipedia.org/wiki/Kernel_(computing)
This guide is for US SGSIII's (d2att,d2cri,d2mtr,d2spr,d2tmo,d2usc,d2vzw,others?)
It may be possible to adapt this to other devices, but I am not responsible for anything that happens should you try to do this.
This guide assumes you have a general knowledge of the Linux operating system. If you've never used it, you might consider playing around
with it for awhile before attempting this guide.
Click to expand...
Click to collapse
Prerequisites
On all devices you must be rooted, on Verizon SGS3 (d2vzw) you must also have the unlocked (VRALE6) bootloader installed.
This is not the thread for figuring out how to do this. You can use the forum's search function to figure out how to do this on your device.
You'll need a computer or a virtual machine running ubuntu. You may be able to figure out how to get this working on other distributions,
but since ubuntu is generally the most accepted distribution to use for building android things, I'll stick to using that here.
At the time of this writing, I'm using ubuntu 12.10, 64-bit.
You'll need to install some packages on your ubuntu machine:
Code:
sudo apt-get install build-essential git zip unzip
On 64-bit you'll also need some multilib and 32-bit compatibility packages:
Code:
sudo apt-get install gcc-multilib g++-multilib lib32z1-dev
Click to expand...
Click to collapse
Setting up the Build Environment
Next, you'll need a toolchain which is used to actually build the kernel. You may download one of these:
GCC 4.4.3: Download || Mirror
GCC 4.6: Download || Mirror
GCC 4.7: Download || Mirror
If you aren't sure, go for 4.4.3 or 4.6.
4.7 requires some code changes to work. The original kernel developer may or may not have made these changes.
Here is what I needed to do in order for 4.7 to build, boot and have wifi work:
https://github.com/invisiblek/linux-msm-d2/commit/f8d7199d37cfbfa1bcb6b4bcae3fc15ae71fbdea
https://github.com/invisiblek/linux-msm-d2/commit/ea58076501e5874db7b934c215c4dae81ddfd0a6
The toolchains are also available in the android NDK.
*** There are many toolchains out there, some of you may know of the Linaro toolchain which is aimed to optimize your binary even further ***
*** If you choose to use a different toolchain, that is fine. Keep in mind that you may run into issues depending on the toolchain you use ***
You can check what your currently running kernel was built with by issuing these commands:
Code:
adb root
adb shell cat /proc/version
It should return something like:
Linux version 3.4.0-cyanogenmod-gc4f332c-00230-g93fb4aa-dirty ([email protected]) (gcc version 4.7 (GCC) ) #134 SMP PREEMPT Thu Feb 28 00:22:41 CST 2013
Click to expand...
Click to collapse
This shows my particular kernel here was built with GCC 4.7
You can use wget to download one of the links from above, in this instance we'll download version 4.4.3 from the first link:
Code:
wget http://invisiblek.org/arm-eabi-4.4.3.tar.bz2
Extract this to somewhere you will remember, probably your home directory.
Code:
mkdir arm-eabi-4.4.3
tar -xf arm-eabi-4.4.3.tar.bz2 -C arm-eabi-4.4.3/
Click to expand...
Click to collapse
Obtaining Source
Find someone's source to use as a base. This can be a source archive from Samsung, a kernel tree from CyanogenMod, or any other developer around that makes kernels for your device.
TIMEOUT
This is a good spot to stop and take note that the Linux kernel is licensed under the GNU General Public License (GPL): http://www.gnu.org/licenses/gpl-2.0.html
What does this mean you ask? It means that if you plan to share your kernel with the community (if it's good, please do so!) then you MUST share your
source code as well. I am not liable for what you choose to do once you start building kernels, but know this: if you share your kernel and do not
provide source code for it, you will get warnings from XDA for a determined amount of time, after that you may have your threads closed, deleted and
possibly your user account terminated. This is extremely important!
Also, you may run into more problems than just XDA. There are organizations out there that do take action if you consistently refuse to comply with the GPL.
I recommend you read this: http://www.gnu.org/licenses/gpl-2.0.html so that you are familiar with what legalities you are getting yourself into.
The main thing to remember is to share your source code if you decide to share your built kernel.
Click to expand...
Click to collapse
In this instance, we will use CyanogenMod's kernel source for the US Galaxy S3's. You may browse the source code here:
https://github.com/CyanogenMod/android_kernel_samsung_d2
You'll notice that the branch there is cm-10.1
This is the default branch of this repository on github. This means that if you intend to build this branch, you'll need to use it on CM version 10.1. Most
likely it will not function on another version.
To obtain the source code:
Code:
git clone https://github.com/CyanogenMod/android_kernel_samsung_d2
This will take a little while, be patient.
When done, you'll have a directory called android_kernel_samsung_d2, cd into this directory.
Code:
cd android_kernel_samsung_d2
Next, you'll need to set up a couple environment variables. These tell the system two things:
1. What CPU architecture to build for, in this case arm
2. Where to find the toolchain we downloaded earlier, so that the system can cross compile for arm
Code:
export ARCH=arm
export CROSS_COMPILE=~/arm-eabi-4.4.3/bin/arm-eabi-
You'll need to set these variables on each new session. You can modify your Makefile in the root of your kernel tree in order to have these set permanently.
Click to expand...
Click to collapse
Building
At this point you can make any changes to the source code that you want. If this is your first time, I recommend not making any changes and make sure you have a
sane build environment before adding any complications.
When you build a kernel, you need to choose a defconfig. This is a specialized configuration file, specifically tailored for your device.
CyanogenMod names their defconfigs for their devices like so: cyanogen_<device>_defconfig and they are located in arch/arm/configs/
Code:
ls arch/arm/configs/cyanogen*
In this example, we will build for d2vzw.
Set up your tree to build for the d2vzw:
Code:
make cyanogen_d2vzw_defconfig
(do this in your kernel's root directory, in this example it was android_kernel_samsung_d2/ )
Now you are ready to build:
First, determine how many cpu's your computer has. You'll use this number to determine how many jobs the compiler command will use. The more jobs you can use, the more
cpu threads the compile will take advantage of, thus you'll get faster builds. If you don't know, just assume you'll use the number 2. We'll use 2 as an example here.
Code:
make -j2
Where 2 is the number of CPU cores your build system has.
And now we wait...until it's done compiling...
You'll know it successfully compiled when you have this line when it stops:
Kernel: arch/arm/boot/zImage is ready
Click to expand...
Click to collapse
PROTIP:
If it stops somewhere other than "zImage is ready" then you had build errors. Try running the 'make' command with no options after it. This will run the compile on a single thread
and will cause it to stop compiling as soon as it hits an error. When you run it on multiple threads, it definitely goes much faster, but if an error occurs, the console doesn't stop
until it finishes all of its threads. Causing you to have to scroll up and search around for an error
Click to expand...
Click to collapse
Now, assuming the build completed successfully, you have two things you are concerned with: A zImage (the kernel binary itself) and your kernel modules, which get built based
on what was configured in your defconfig.
You'll find your zImage at: arch/arm/boot/zImage
Code:
ls arch/arm/boot/zImage
The modules are scattered all over the place, depending on where the source existed that they were compiled from. We can easily search for them using this command:
Code:
find . -name "*.ko"
If both of the previous commands completed, you are now ready to package your kernel up for testing.
Move up a directory before continuing.
Code:
cd ..
Click to expand...
Click to collapse
Packaging
You may know of an awesome developer by the name of koush.
Well, once upon a time, koush created a rather simple zip, called AnyKernel, that would flash a kernel on a device, regardless of what ramdisk the kernel has on it.
I've taken his zip and modified it for d2 devices and to work with the newer recoveries out there.
This has a script in it that will dump your current boot.img (kernel+ramdisk), unpack it, replace the kernel, repack it and flash it.
It'll also copy any modules to the proper directory (/system/lib/modules) and set permissions appropriately.
You can get a zip here: Download || Mirror
(You can get it here as well: https://github.com/invisiblek/AnyKernel )
(Everyone is invited to use this zip, it'll probably make your life easier to not have to worry about the ramdisk. Enjoy!)
IMPORTANT
This AnyKernel package is for US variations of the Galaxy S3.
NOT the international (I9300) or any other device.
There are checks in the updater-script that will ensure you are running a d2 device before it does anything.
If you were to remove these checks, and not modify the partition that it flashes to later, you could end up with a brick.
If you intend to adapt this package for another device (please, do this! its a very handy script!), make sure you know it well, or ask someone to help you determine your device's
partition scheme before using it.
The risk here is due to the fact that the script doesn't know your device's partition scheme. It is configured specifically for the d2 devices. Flashing it on something else, who's boot
partition is somewhere else, might cause a bad flash to the bootloader partition (bad bad news if this happens).
Just be careful if you want to use this on another device. You won't run into problems if you use this on a d2 device.
EDIT: I made modifications that should make this less likely, but please, if you intend to use this on a different device (which is completely fine!) make sure you configure
the scripts to flash to the proper partitions.
Click to expand...
Click to collapse
Download and extract one of the above, we'll again use the first link for this example:
Code:
wget http://invisiblek.org/AnyKernel_samsung-d2.zip
unzip AnyKernel_samsung-d2.zip -d AnyKernel/
Now we'll copy our newly compiled zImage (still referring to the same kernel directory we used above, your repo might be called something different)
Code:
cp android_kernel_samsung_d2/arch/arm/boot/zImage AnyKernel/kernel/
cp `find android_kernel_samsung_d2 -name "*.ko"` AnyKernel/modules/
Finally we are ready to zip this up and test out flashing it.
Code:
cd AnyKernel
zip ../MyAwesomeKernel.zip -r *
cd ..
You'll now have a file named MyAwesomeKernel.zip which you should be able to flash via custom recovery (TWRP or CWM)
Click to expand...
Click to collapse
Extra Credit/Protips
Learn to use git. It's very powerful and great way to store your code.
Learn to use adb. It's an invaluable tool for any android developer.
Touchwiz and AOSP-based kernels are different. This means you cannot take CyanogenMod's source, build a kernel and expect it to work on a Touchwiz-based ROM.
Build a ROM next: http://wiki.cyanogenmod.org/w/Build_for_d2vzw
Crackflash your own stuff!
ALWAYS NANDROID!
Click to expand...
Click to collapse
Source code for all of my projects can be found here: http://github.com/invisiblek

FAQ
Q: How do I update my source tree to the latest that is available from where I downloaded it?
A: This can be handy if, for instance, you are building a CyanogenMod kernel and they added some patches, after you downloaded the source, that you want to include in your next build. You'll want to cd to your kernel tree and issue a git pull:
Code:
cd android_kernel_samsung_d2
git pull
You may then continue with the building instructions.
This may, however, have other problems if you've made changes to files. You might run into conflicts. I won't cover fixing any of this here, its not in the scope of this thread.
Q: I'm using X as a kernel base, but Y has a patch that I really like. How do I get it in my kernel easily?
A: I'll let you check Google for this answer, but I'll give you a hint use: git cherry-pick

Nice tutorial bro! Always good to learn something new everyday

Really is a good thread，thanks

This guide would have made things too easy for me.
Too easy, indeed. haha
Great job, invisiblek! AnyKernel is the beez neez.

Ok so this is a noob question but I gotta ask anyway lol. Ok so I cloned the kernel source, I made my edits, now how do I push all this to my github?
I already have a github account, I already made a new repo for the kernel. Here's a link to my github if you need it...
https://github.com/ghicks12/d2vzw_kernel.git

spc_hicks09 said:
Ok so this is a noob question but I gotta ask anyway lol. Ok so I cloned the kernel source, I made my edits, now how do I push all this to my github?
I already have a github account, I already made a new repo for the kernel. Here's a link to my github if you need it...
https://github.com/ghicks12/d2vzw_kernel.git
Click to expand...
Click to collapse
git remote add origin git_location_you_created_on_github.git
git push -u origin somebranch
The -u is for first time run only, you can just git push afterwards.
Sent from my SCH-I535

GideonX said:
git remote add origin git_location_you_created_on_github.git
git push -u origin somebranch
The -u is for first time run only, you can just git push afterwards.
Sent from my SCH-I535
Click to expand...
Click to collapse
Thanks! When I run
Code:
git remote add origin https://github.com/ghicks12/d2vzw_kernel.git
I get this back:
Code:
fatal: remote origin already exists.
I'm editing a CM based kernel, not sure if that matters or not?

That just means you added the remote already. Just issue the push command then.
Sent from my SCH-I535

Why is this happening? I don't know what i did wrong
[email protected]:~/cm$ make VARIANT_DEFCONFIG=cyanogen_d2att_defconfig
scripts/kconfig/conf --silentoldconfig Kconfig
drivers/media/video/msm/Kconfig:123:warning: choice value used outside its choice group
drivers/media/video/msm/Kconfig:128:warning: choice value used outside its choice group
***
*** Configuration file ".config" not found!
***
*** Please run some configurator (e.g. "make oldconfig" or
*** "make menuconfig" or "make xconfig").
***
make[2]: *** [silentoldconfig] Error 1
make[1]: *** [silentoldconfig] Error 2
make: *** No rule to make target `include/config/auto.conf', needed by `include/config/kernel.release'. Stop.
[email protected]:~/cm$

Hey. I'm having some problems with some GIT terminology and procedures. I'm a .NET developer and I use TFS and SVN on a daily basis. Forgive me if this is complete off basis from what you'd do with GIT.
What I want to do is merge one branch into another branch. In other words I want to take the latest kernel source from my favorite dev and merge in the latest from cyanogen's 4.3 d2 branch. Is this a rebase thing? It doesn't seem like cherrypicking to me.

I have successfully compiled kernel and made modules.I inserted zImage and modules inside any kernel updater,flashed via TWRP.When reboot stuck in odin and it says could not do normal boot.

[GUIDE] [BIN] Compile busybox on Linux

About Busybox: busybox.net/about.html
More on Busybox: busybox.net
This is just for anyone who wants to try, and especially those without access to a PC.
:
: --------------- BUILD STEPS --------------
:
Things we'll need besides your phone:
- "Android Terminal Emulator" app
- "Complete Linux Installer" app , I also recommend trying "linux deploy" for more advanced usage
- internet/wifi
- latest "busybox" source
1) We need to get Ubuntu or Debian booted for a sufficient build environment (kali linux works well too). I've used them all on Android but I like the better stocked terminal in the Ubuntu images. I used the app "Complete Linux Installer" which is free and works beautifully, very simple and easy. In the app you want to follow the short instructions to download an Ubuntu image, rename it to ubuntu.img, and place it in a folder named ubuntu in /sdcard. Then hit menu in the app and click the terminal screen icon that says "Launch". An Ubuntu terminal will now open in Android Terminal Emulator. Super quick and easy.
2) Let's download some crucial build environment tools.
Code:
apt-get install -y gcc build-essential libncurses5-dev libpam0g-dev libsepol1-dev libselinux1-dev
--EDIT-(30AUG2014)--
For Selinux compatibility and loginutils, we need to also download a few extra packages. Already included in the code above.
3) Now the cool thing about this chroot Ubuntu environment is that we still have access to the sdcard to transfer files between Android environment and the chroot jail. Extract your downloaded busybox source to your Ubuntu home with something like:
Code:
cd
tar -xf /sdcard/Download/busybox*bz2
cd busybox*
4) Now we can build busybox statically. The first thing we do is generate a Makefile by running "make" with a "defconfig" (default configuration file) Usually you will run "./configure" with other programs, but busybox compiles more like a kernel, so it uses a config which has a huge checklist of options.
(After successfully compiling busybox, we can go back and customize the .config; this entails that for each "CONFIG ..." line we see, we can uncomment it and mark it "y" or "n" to configure some option... This can be more easily done from a terminal busybox menu interface with "make menuconfig". You just need to crank font down to 7 or use telnet/ssh)
Skip "make defconfig" if you use a customized ".config" file such as one I've attached.
Code:
make defconfig
If all goes well, we now have a Makefile and are ready to compile:
Code:
make clean && make LDFLAGS=-static
Let "make" crank out the binary for a couple minutes. The extra variable we set after make is to compile statically. When compiling is complete we'll have a few different busybox binaries at the root of the source directory. We use the one named "busybox" since we're not debugging.
5) Now let's copy it to /system/usr/bin to install for test usage.
Code:
cp ./busybox /android/data/media/0
(Open a new terminal tab to get into Android Environment)
mount -o remount,rw /system
mkdir -p /system/usr/bin
cp -f /sdcard/busybox /system/usr/bin
chmod 0555 /system/usr/bin/busybox
/system/usr/bin/busybox --install -s /system/usr/bin
mount -o remount,ro /system
PATH+=:/system/usr/bin
.. and done. Run some scripts and enjoy your static busybox!
:
: Extra steps for SELinux-enabled busybox
:
Here are the extra steps you need to take to compile busybox with SELinux features. Sorry it took so long to get this added to this first post.
First we need to download the source for libselinux and libsepol and compile it. (This is for use with the standard glibc toolchain.)
Code:
cd
apt-get source libselinux libsepol
cd libselinux*
make
cd
cd libsepol*
make
Now that we have those libraries compiled, we can proceed to the busybox compilation.
Code:
cd
cd busybox*
make clean && make LDFLAGS='-static -L ../libselinux*/src -L ../libsepol*/src' CFLAGS='-Os -I ../libselinux*/include -I ../libsepol*/include'
That's pretty much it. It initially seems more complicated than it actually is, but all we're really doing is including the libraries for libselinux and libsepol into the busybox compilation.
edit:
**Commands to run if you have compile errors:
Code:
apt-get build-dep busybox
apt-get install -y build-essential
apt-get -f update
dpkg --configure -a
:
: --------------- DOWNLOADS --------------
:
***** Attached are flash installers for busybox (v1.23.1 stable, non-SELinux, 374 applets included!, ~1.1MB size) or busybox (v1.23.1 stable, SELinux, 386 applets included!, ~1.6MB size) *****
Since it's up-to-date it has some nice extras most people haven't seen like a "-I" option for xargs! Yes, that is correct, busybox xargs has its testicles back.
Code:
e.g.
$ echo Hello | xargs -I{} echo {} world!
> Hello world!
: ---------- UPDATES ----------
-------------------EDIT-2-(30AUG2014)----------------------
Got a Selinux-enabled busybox attached now. This means Selinux flags are integrated into applets like ls, id, ps, etc, and there are now 12 extra Selinux applets to give a total of 386 applets, ~1.6MB in size. The previous one is more portable, but this one can completely replace toolbox and gives you Selinux control for Android 4.4+. Plus it's pure maxed-out awesomeness.
***I've also attached the .config files for each busybox I've compiled, so anybody can remake them (from their phone!) as I've posted. You just need to download and extract the .config file to the root of your busybox source directory and type "make".***
-------------------EDIT-3----------------------
YashdSaraf has made some very useful flash zips to install either the non-selinux- or selinux-enabled busybox 1.23.1 via recovery. Installation replaces the stock busybox in /system/xbin. I've attached the zips he made to the end of this OP.
(**Note: Thought I'd mention that there will be a handful of applets that don't work in "Android" environment such as su(don't worry this isn't linked with the installer) Part of this is because of the way Android's default file structure is an amputated modified version of linux. With almost all of them, slight modifications to environment and file structure can be made to get them to work. This is just normal behaviour of busybox in android. The su and init applets shouldn't be used in Android though. I keep them compiled into the binary anyway for completeness of the build and because they work and are needed for a root.gz initrd or some chroot environments. It also doesn't hurt keeping them compiled in. You just have to remember not to link them when installing busybox.
-------------------EDIT-4-(06SEPT2014)----------------------
:
: How to compile against(using) uclibc for a smaller binary!!
:
Download the attached arm-linux-uclibcgnueabi toolchain package that I pre-compiled. Extract to /data/media:
Code:
cd /data/media
zip='/sdcard/Download/2014-09-06__arm-buildroot-linux-uclibcgnueabi.tar.lz.zip'
unzip -op "$zip" | lzip -d | tar -xf -
Then let's open up the "Complete Linux Installer" or "Linux Deploy" terminal.
To use the toolchain with a busybox build, we just need to specify the parameter CROSS_COMPILE which is a prefix to the compiler tools. So if you extracted the toolchain to /data/media, you will use:
Code:
make clean && make LDFLAGS=-static CROSS_COMPILE=/android/data/media/arm-buildroot-linux-uclibcgnueabi/bin/arm-buildroot-linux-uclibcgnueabi-
When you're done you should have a busybox binary with 374 functions with size around 1.1MB. That's a 20% decrease in size from using the standard glibc toolchain!
**IMPORTANT Notes
- The toolchain can't be used with lollipop since it's not compiled with -fPIC. I'll fix this later. Busybox is fine since it's static, it's just the toolchain I uploaded.
- Selinux-enabled busybox .config errors out when building using the uclibc toolchain; I think this is a lack of support issue. In the "Complete Linux Installer" app you'll need to add the mount "/data/media" in options. This gives you access to it as "/android/data/media", very very useful for extra space needs.
Difference between SELinux and non-SELinux busybox
The SELinux (NSA security enhanced Linux) binary comes with the following extra utilities: chcon, getenforce, getsebool, load_policy, matchpathcon, restorecon, runcon, selinuxenabled, setenforce, setfiles, setsebool, and sestatus. There are also some selinux flags enabled for applets such as "ps" and "ls", e.g. "ps -Z" and "ls -Z" to show the context for processes or files. If you are using Android 4.3 or newer, then you probably want to use the SELinux-enabled busybox since Android 4.3 is when SELinux was introduced to Android. Using the SELinux busybox on older version of Android without SELinux file structure should probably work besides the SELinux applets, but I haven't tested this. The non-SELinux binary can be used on any version of Android. When it comes down to it, the system actually uses "/system/bin/toolbox" SELinux applets for SELinux operations, so unless you specifically want to use busybox's SELinux tools for personal use, the safest option is to go with the non-SELinux busybox. I use Android 4.3.1 and 5.x, so I use busybox's better featured SELinux tools.
Latest updates see post 2
Busybox 1.23.1 (2015-02-06) below

Busybox compilation on Linux
reserved

Great Info here!
But I would be interested to know how well this method works on Samsung Stock devices running AOS 4.2 and above? Any experience?

Awesome info, this thread came up #1 while googling busybox 1.23
I made a flashable zip of the attached binary in the op to clean the old one(if any) and install the new busybox in xbin, just in case if anyone needs it. :good:

Is it work on xperia sp on 4.3 fw yes ?

YashdSaraf said:
Awesome info, this thread came up #1 while googling busybox 1.23
I made a flashable zip of the attached binary in the op to clean the old one(if any) and install the new busybox in xbin, just in case if anyone needs it. :good:
Click to expand...
Click to collapse
Thanx,worx fine with Carbon 4.4.4 on my LG.
GREETZ FROM TEAM-OPTIMA!!!

E:V:A said:
Great Info here!
But I would be interested to know how well this method works on Samsung Stock devices running AOS 4.2 and above? Any experience?
Click to expand...
Click to collapse
Thanks man. I've been compiling tons of stuff with Debian and Ubuntu chroot no problem on top of 4.3.1 Vanir and also 4.4.4 Carbon, both are my daily drivers. "Complete Linux Installer" is pretty fast compared to some other chroot apps like GNUroot (no offense to GNUroot, it works but is way too slow). It runs real-time compared to non-chroot. When compared to my dual-core 2007 Pentium M laptop, it's about 2-3 times as slow which isn't too bad for compiling something like mksh or even busybox which takes up to 5 mins I'd say.
In terms of binary size, compiling natively is better than cross-compiling it seems. I used gcc with no size optimizations here, so 1.37MB is pretty nice compared to some others around 2MB with full configs. With this method and klcc (gcc wrapper) I got mksh compiled to 192KB. I'm currently trying to build a uclibc toolchain on my laptop that will give me a mksh binary under 300KB..
YashdSaraf said:
Awesome info, this thread came up #1 while googling busybox 1.23
I made a flashable zip of the attached binary in the op to clean the old one(if any) and install the new busybox in xbin, just in case if anyone needs it. :good:
Click to expand...
Click to collapse
Cool thanks man! That is really useful, glad to hear from CALIBAN that it works. Could I add this to the OP with credit to you?
Hamidreza2010 said:
Is it work on xperia sp on 4.3 fw yes ?
Click to expand...
Click to collapse
Yes, xperia sp uses armv7 so you should be good to go.

7175 said:
Cool thanks man! That is really useful, glad to hear from CALIBAN that it works. Could I add this to the OP with credit to you?
Click to expand...
Click to collapse
Sure bro go ahead
Edit: Went ahead and made one for selinux enabled busybox :silly: , you can add this one in the op too.

Hey guys I was able to get an entire uClibc toolchain built the other day (using buildroot). I tested it and it makes some nice small binaries with about 20%+ smaller size than the standard glibc. Man that took hours to compile but was well worth it. It really put the stability of Android OS to the test as well. Kitkat absolutely couldn't finish compiling with multiple oom's and oops's, but Vanir 4.3.1 stuck it out real nice. Once I had the huge amount of required buildroot packages downloaded, I was able to compile in TWRP as well with good stability. (I have the "Complete Linux Installer" startup chroot script aliased in my mkshrc so I can pull up an ubuntu terminal without starting the app. )
So I got 3 new attachments to OP:
- arm-linux-uclibc toolchain for anyone who wants to compile stuff with it (host=arm AND target=arm)
- busybox (374 fcns, non-selinux) 1116KB
- lzip binary (in case you need it to unzip the toolchain, which is highly compressed from 64MB to 14MB with lzip's lzma)
**As I mentioned in the updated OP, I wasn't able to get selinux-enabled busybox compiled with uclibc. This may be something unsupported, or there may be a patch fix. I'll check it out. I'll try with musl libc and musl-gcc as well.

I have another approach, I try aboriginal cross compiler toolchain in archLinux it produced small binary, but I can't compile busybox for android. For Linux it work. Maybe need bionic lib?

ndrancs said:
I have another approach, I try aboriginal cross compiler toolchain in archLinux it produced small binary, but I can't compile busybox for android. For Linux it work. Maybe need bionic lib?
Click to expand...
Click to collapse
Sounds interesting. I honestly haven't given this a try yet, but I'm very interested in taking a look at it. At this point I'm pretty much addicted to making the smallest binaries I can and testing out different toolchains. I'll give it a good search on duckduckgo, and if you have any insightful links that would be great.
Edit: Alright cool I found the source for Aboriginal Linux at landley.net/aboriginal and am building on Android now. I'm also trying this on my x86_64 laptop so that I can compare the differences like I have with glibc, uclibc, musl, klibc binary builds in a native environment and a cross-compile environment.
I see from my laptop's build that a busybox was generated, but it was dynamic and has a libc.so.6 dependency. @ndrancs : this might be what you were talking about. Did you try compiling static? Also see if "make allnoconfig && make clean && make LDFLAGS=-static" works for compiling busybox with Aboriginal Linux.

7175 said:
Edit: Alright cool I found the source for Aboriginal Linux at landley.net/aboriginal and am building on Android now. I'm also trying this on my x86_64 laptop so that I can compare the differences like I have with glibc, uclibc, musl, klibc binary builds in a native environment and a cross-compile environment.
I see from my laptop's build that a busybox was generated, but it was dynamic and has a libc.so.6 dependency. @ndrancs : this might be what you were talking about. Did you try compiling static? Also see if "make allnoconfig && make clean && make LDFLAGS=-static" works for compiling busybox with Aboriginal Linux.
Click to expand...
Click to collapse
I preferred to use uclibc I think it easy to setup and produced small binary.. Aboriginal cross-compiler use uclibc as default. Btw I don't use cmd : LDFLAGS=-static instead I set it in .config.. Maybe I try this later..

ndrancs said:
I preferred to use uclibc mk it easy to setup and produced small binary.. Aboriginal cross-compiler use uclibc as default. Btw I don't use cmd : LDFLAGS=-static instead I set it in .config.. Maybe I try this later..
Click to expand...
Click to collapse
Ok yeah I like how aboriginal set up with uclibc, and it has scripts for each build stage, so you can stop at the toolchain. I'll be interested to see their future releases with the musl libc as well.
Also for anyone interested, I figured out how to run dynamic binaries in android:
- make the directories "/lib" and "/lib/arm-linux-gnueabihf"
Code:
mkdir -p /lib/arm-linux-gnueabihf
- copy the linker "ld-linux-armhf.so.3" to "/lib"
- find a specific binary's dependencies: e.g. for dynamic mksh do:
Code:
strings mksh | grep \\.so
- copy the listed libs to "/lib/arm-linux-gnueabihf": e.g. for mksh that would be libc.so.6. The libs/linker you copy over will come from the mounted ubuntu/debian/... image you have mounted like with "Complete Linux Installer".
- adjust your LD_LIBRARY_PATH:
Code:
LD_LIBRARY_PATH=/lib:/lib/arm-linux-gnueabihf:$LD_LIBRARY_PATH

Any plan to update the busybox to current version. Thanks.

@7175 can you update flashable zip to 1.23.0 stable ?

@ndrancs @exodius48 : Thanks for notifying me guys, I needed to get around to updating to 1.23.0 stable. I updated the original post with no-edify installers for busybox 1.23.0 stable. There's a non-SELinux uclibc compiled version and a full 386-applet SELinux glibc compiled version. They're included in this post too for ease.

7175 said:
@ndrancs @exodius48 : Thanks for notifying me guys, I needed to get around to updating to 1.23.0 stable. I updated the original post with no-edify installers for busybox 1.23.0 stable. There's a non-SELinux uclibc compiled version and a full 386-applet SELinux glibc compiled version. They're included in this post too for ease.
Click to expand...
Click to collapse
Great..been waiting for this release.. :good:
Btw, can i use busybox_full_selinux.zip on android 4.2.2 MIUI rom?

exodius48 said:
Great..been waiting for this release.. :good:
Btw, can i use busybox_full_selinux.zip on android 4.2.2 MIUI rom?
Click to expand...
Click to collapse
Yeah that should work just fine. I'm pretty sure any SELinux tools or applet flags should work since 4.2 introduced SELinux to its filesystem. Let me know if there are any issues.

7175 said:
Yeah that should work just fine. I'm pretty sure any SELinux tools or applet flags should work since 4.2 introduced SELinux to its filesystem. Let me know if there are any issues.
Click to expand...
Click to collapse
Great release..busybox_full_selinux.zip working fine so far on MIUI rom V5 android 4.2.2. :victory:

7175 said:
@ndrancs @exodius48 : Thanks for notifying me guys, I needed to get around to updating to 1.23.0 stable. I updated the original post with no-edify installers for busybox 1.23.0 stable. There's a non-SELinux uclibc compiled version and a full 386-applet SELinux glibc compiled version. They're included in this post too for ease.
Click to expand...
Click to collapse
Hey @7175
Great guide. I am able to compile just fine on my device using your guide. However, is there any way to compile the selinux applets support using a Linux PC (or NDK)? I am not able to find a selinux supported toolchain. May be you can help.

Kernel compilation/booting troubleshooting for beginners

I've only recently after lot of struggle compiled my first kernel. While the information is still fresh in my mind, I want to share all the problems I encountered and what to do if you are in the same situation.
This guide is mainly for Linux users since that is what I am familiar with.
I've used this amazing guide to learn the basics. If you haven't yet, read it first.
Errors from scripts/gcc-wrapper.py
Open the file and change the first line from
Code:
#! /usr/bin/env python
to
Code:
#! /usr/bin/env python2
Kernel won't compile
* Did you forget to set and export the variables ARCH and CROSS_COMPILE?
* Do you have the right .config file present?
Try extracting the .config file from the original boot kernel and use it instead
* Are you sure you are in the correct branch?
Run git branch inside kernel's source code to verify that
* Are you using a very recent or very old version of the compiler? Some old kernels for example would only compile with gcc-4 but not gcc-7 or 8. Most kernels - at the time of writing - won't compile with gcc-8
Kernel compiles fine but won't boot
* Are you using wrong kernel configuration (.config) ?
* Try different compiler or different compiler version.
I've tried to compile my current with Android's prebuild gcc 4 compiler and it wouldn't boot, switched to gcc 7 and it booted perfectly fine.
Kernel starts but system crashes somewhere during boot
You can enable adb during boot so that you can see what causes the error.
Find this file in your extracted boot image ramdisk/default.prop
Set or update the following values
Code:
ro.adb.secure=0
ro.secure=0
persist.sys.usb.config=adb
Then you can do adb shell logcat or adb shell dmesg to see what is going on
My phone won't boot after flashing my new kernel, how do I boot to recovery?
First of all, you shouldn't have! You should test your new kernel without flashing it using fastboot.
Simply reboot to bootloader then run the command
Code:
fastboot boot /path/to/my/new-image
So what can I do now? Try to reach bootloader screen. the method differs from device to device but it involve pushing certain physical phone buttons while turning on the phone.
Once you are in the bootloader screen, you can do adb fastboot /path/to/twrp-recovery.img or even path to original boot image if you kept a backup.

ramast_ said:
I've only recently after lot of struggle compiled my first kernel. While the information is still fresh in my mind, I want to share all the problems I encountered and what to do if you are in the same situation.
This guide is mainly for Linux users since that is what I am familiar with.
I've used this amazing guide to learn the basics. If you haven't yet, read it first.
Errors from scripts/gcc-wrapper.py
Open the file and change the first line from
Code:
#! /usr/bin/env python
to
Code:
#! /usr/bin/env python2
Kernel won't compile
* Did you forget to set and export the variables ARCH and CROSS_COMPILE?
* Do you have the right .config file present?
Try extracting the .config file from the original boot kernel and use it instead
* Are you sure you are in the correct branch?
Run git branch inside kernel's source code to verify that
* Are you using a very recent or very old version of the compiler? Some old kernels for example would only compile with gcc-4 but not gcc-7 or 8. Most kernels - at the time of writing - won't compile with gcc-8
Kernel compiles fine but won't boot
* Are you using wrong kernel configuration (.config) ?
* Try different compiler or different compiler version.
I've tried to compile my current with Android's prebuild gcc 4 compiler and it wouldn't boot, switched to gcc 7 and it booted perfectly fine.
Kernel starts but system crashes somewhere during boot
You can enable adb during boot so that you can see what causes the error.
Find this file in your extracted boot image ramdisk/default.prop
Set or update the following values
Code:
ro.adb.secure=0
ro.secure=0
persist.sys.usb.config=adb
Then you can do adb shell logcat or adb shell dmesg to see what is going on
My phone won't boot after flashing my new kernel, how do I boot to recovery?
First of all, you shouldn't have! You should test your new kernel without flashing it using fastboot.
Simply reboot to bootloader then run the command
Code:
fastboot boot /path/to/my/new-image
So what can I do now? Try to reach bootloader screen. the method differs from device to device but it involve pushing certain physical phone buttons while turning on the phone.
Once you are in the bootloader screen, you can do adb fastboot /path/to/twrp-recovery.img or even path to original boot image if you kept a backup.
Click to expand...
Click to collapse
good job!
Do you have any general tutorials on kernel optimization?

wangyiling said:
good job!
Do you have any general tutorials on kernel optimization?
Click to expand...
Click to collapse
I am afraid not, sorry. I am just a beginner

@ramast_
The information you provided has solved pretty much all of the problems I was having. We need more content like this. Everything I find about kernel building explains things like you're a Linux expert, where as your post is much more layman friendly. I can't thank you enough for this.
Quick question; which version of Linux do you use?

You are very welcome, happy someone found it useful.
By Linux version I suppose you mean Linux distro (distribution).
I use Gentoo which is certainly not for beginners.
I'd suggest Ubuntu for beginners. Not because it's the best but because it has a very big community and you are more likely to find help when facing any problem.
This article explain how to cross compile arm code (how to compile code so that it can run on an arm device). Should get you started.
Best of luck
Spaceminer said:
@ramast_ I can't thank you enough for this.
Quick question; which version of Linux do you use?
Click to expand...
Click to collapse

ramast_ said:
You are very welcome, happy someone found it useful.
By Linux version I suppose you mean Linux distro (distribution).
I use Gentoo which is certainly not for beginners.
I'd suggest Ubuntu for beginners. Not because it's the best but because it has a very big community and you are more likely to find help when facing any problem.
This article explain how to cross compile arm code (how to compile code so that it can run on an arm device). Should get you started.
Best of luck
Click to expand...
Click to collapse
Thanks again. Distro is what I meant. I was thinking I should use Ubuntu, but I wanted to see what you had to say about it.

[Guide] Building post 2017 android kernel from source

About this guide
I have been building kernels for many machine types and have been fiddling around with custom android kernels for my own phone but to my great frustration the rules changed quite a lot for my new phone. It seems every kernel after 2017 is A LOT harder to build and needs quite some fiddling around te get it to boot. The documentation is terrible the least on the steps and all howtos are all outdated by now. This guide shares with you the secrets to build yourself a modern post 2017 kernel from source. I only own a op7 at this moment but I am pretty sure the rules apply to all devices.
So why do we need to build our own kernel? Well that's simple. I have scrolled through many custom kernels missing a simple module that I need. In my case binfmt. Perhaps you need a specific device driver compiled into your kernel or you want to hack in/patch in some special functions that are only needed by you. Or you love a certain kernel but need that one little adjustment in the configs that this kernel doesn’t have and so on.
Lets get through it step by step but I do assume you know something about Linux, you know how to use the terminal and that you have some knowledge on building binaries from source. Ready? Ok lets get started.
These steps are required to be followed to be successful:
1. Set up a building environment
2. Obtain the kernel source
3. Download the proper tool-chain
4. Adjust configuration files to match your needs
5. Build the actual kernel image
6. Backup your current boot.img!!!
7. Trow the image into a anykernel zip and flash it.
8. Close your eyes prey and run the kernel.
Prerequisites
You will need:
A fairly fast computer with lets say 4 gigs of RAM and a decent CPU.
A workable linux distribution that you can boot into (I prefer ubuntu bionic at this moment).
The kernel sources for your device.
ROOT!!
Lots of spare time.
A attitude that makes you unstoppable.
1. Setting up the building environment
Ok lets first open a terminal. You will need the terminal a lot. As a matter of fact it will be your friend through this guide so better get used to it. Assuming you are on a ubuntu like distribution lets fetch the important packages first
Code:
$sudo apt install build-essential bizon flex git
This command will install some of the prerequisites you need to do anything. More packages will need to be installed on the way but at least you will be able to type $make
Now lets create a working directory. Go into your home folder and create a working directory which will later on contain your kernel sources and tool chain.
Code:
$cd
$mkdir [COLOR="MediumTurquoise"]name-of-your-working-folder[/COLOR]
2. Obtain the kernel source
This one is tricky as my experience have learned me the kernel sources supplied by my own vendor are usually badly documented and contain a few bugs here and there resulting in either build errors or a unbootable kernel. So usually I grab a custom kernel that has minimal changes to the stock kernel and boots by only using a single kernel file without extra kernel modules attached. The custom kernels usually have the nasty building bugs flawed out and thus your chances for success are higher. I used the exkernel in my case and out of respect for the hard work of flang2 I bought the app that came along.
To get the sources google around and find the sources on for example git and click the download or clone button there and copy the link of the depository.
Then simply clone the depository to your working directory so after changing to your working directory type
Code:
$git clone link-you-just-copied
Git will now automatically clone the entire kernel source into the source sub-directory. You can change the name of this directory to make you life easier.
3. Download the proper tool-chain
This is where I lost many days and weeks of my life. Where do we find the proper tool-chain for our kernel?
You basically need 3 compilers
clang
GCC
device-tree-compiler
There are many versions of clang and GCC and you will need to find the one that matches your kernel and builds for your cpu architecture. I will assume in this guide that your CPU is aarch64 or arm64 (both names are used at the same time).
To obtain clang head over to the following address:
"https://android.googlesource.com/platform/prebuilts/clang/host/linux-x86/"
now in the tags and branches you can find the version of android you are looking for. If your kernel is for android 9 then use the android 9 tag. Click on it and then click tgz which will provide you with a huge tarball.
Create a folder in your working directory named toolchain en extract the contents of the tarball into the sub-folder clang.
You can try any subversion of clang there is but I recommend to simply peek into the build.config files located in the root of your kernel source directory which usually specify the exact subversion of clang used.
Time to get GCC which is easier since there is only one version right now.
Head over to
"https://android.googlesource.com/platform/prebuilts/gcc/linux-x86/arm/arm-linux-androideabi-4.9/"
and use the correct version here as well. In my case I picked the latest build. Then do the same as for clang but name the sub-folder GCC or whatever you please to do.
And then finally get yourself the device-tree-compiler
Head over to
"https://github.com/dgibson/dtc/tree/v1.4.4"
and clone this depository into ~/your-working-directory/toolchain/
and navigate to the subdir you cloned it into
then build by typing
Code:
$make
any missing package errors will need you to install them using
Code:
$sudo apt install missing-package-name
and do make again until the build completes.
If all went well your tool-chain and working directory will look like this:
Code:
/[COLOR="mediumturquoise"]current-working-dir[/COLOR]/[COLOR="mediumturquoise"]kernel-source-dir[/COLOR]/
|
/toolchain/
|
/clang/
/gcc/
/dtc/
4. Adjust configuration files to match your needs
Lets first grab the correct defconfig file and setup the build directory. This defconfig file contains the default kernel configuration parameters which you propably want to adjust.
Head over to ~/working-directory/kernel-source-dir/arch/arm64/configs/
see what you can find there. I found the elementalX_defconfig file which is the file I needed to build the Exkernel from scratch. If you are trying a stock kernel dive a little bit deeper into the vendor folder and see if you can find a good config file there.
Alternatively sometimes the config is hidden on your device itself. Have a look at
/proc/config.gz
the file inside the archive contains a valid defconfig for your device but beware your may need to open it with menuconfig first and save it again to make it workable for the compiler script.
Place the defconfig file you like to use into the configs folder.
(Skip the following step if your are going to build your kernel for the first time because we first want to see it work.)
Now head over to your kernel source dir and type the following command
Code:
$PATH="~/[COLOR="mediumturquoise"]working-dir[/COLOR]/toolchain/clang/[COLOR="mediumturquoise"]clang-r353983c[/COLOR]/bin:~/[COLOR="mediumturquoise"]working-dir[/COLOR]/toolchain/gcc/a[COLOR="mediumturquoise"]arch64-linux-android-4.9[/COLOR]/bin:${PATH}" \
make menuconfig O=out \
ARCH=arm64 \
CC=clang \
CLANG_TRIPLE=aarch64-linux-gnu- \
CROSS_COMPILE=aarch64-linux-android-
now remember to use the correct paths to your tool-chain. In this command I use clang-r353983c but you may use a different version. The same applies for linux-android-4.9.
I would like to thank Nathan Chance for supplying documentation on the clang tool-chain on his github.
If all well you will be presented with a menu in which you can adjust things. First open the defconfig file you wish to use and then save the file after you are done. Now REMEMBER! With this command the menuconfig will save your new file into the /kernel-source-dir/out folder.
(end of the skipped step)
Now it is time to prepare our kernel build using the following command (do this from your kernel source dir) and remember that this command will look in the /kernel-source-dir/arch/arm64/configs/ directory
$make O=out ARCH=arm64 name-of-your-defconfig
If all goes well you will see something like configuration written to .config
Everything is up and ready to go. Your hart will start pounding from this moment on
5. Build the actual kernel image
This is where things get complicated. I hope you have many years to live because this part consumes time, a lot of it.
type
Code:
$PATH="~/[COLOR="mediumturquoise"]working-dir[/COLOR]/toolchain/clang/[COLOR="mediumturquoise"]clang-r353983c[/COLOR]/bin:~/[COLOR="mediumturquoise"]working-dir[/COLOR]/toolchain/gcc/[COLOR="mediumturquoise"]aarch64-linux-android-4.9[/COLOR]/bin:${PATH}" \
make -j$(nproc --all) O=out \
ARCH=arm64 \
CC=clang \
DTC=~/[COLOR="mediumturquoise"]working-directory[/COLOR]/toolchain/dtc/dtc \
CLANG_TRIPLE=aarch64-linux-gnu- \
CROSS_COMPILE=aarch64-linux-android-
ready set GO!
This will depending on your machine take between forever and eternally. You will witness many warnings on the DTC build seems normal these days and a few warnings on the CC part. Most important is that no errors are thrown at you.
If all goes well you will see a normal exit status and you will have a “working” kernel image.
“Error?: Well that happens. Try a different build of clang check your command line. And if all that fails try to find out what is wrong in the source and that means digging through thousands of forum pages until you find out whats wrong. But using the google tools usually goes well.”
Almost there go and check
kernel-source-dir/out/arch/arm64/boot
and there should be a image-dtb or image.gz-dtb file depending on you settings.
That is your kernel image right there. The difference in size between image and image-dtb should not be huge. 10Megs in difference usually means your dtb is not good but trying is the only way to find out if it works.
6. Backup your current boot.img!!!
You know what to do here right? Do not skip this step unless you like bricked devices or want to reflash and lose your data and all that kind of stuff. Not sure what you are doing stop here or backup your entire device including system vendor etc.
7. Trow the image into a anykernel zip and flash it.
Ok something changed in the last few years. Unpacking repacking and booting using fastboot somehow gives me problems. Dm-verity errors and all kind of red screens. Signing the boot image results into new errors. Well this is how I did it.
Get yourself a anykernel zip file. I used the Exkernel.zip because it only contains a kernel image which I like. Open the zip in a good zip tool (I used ark) and replace the image-dtb file with the one you created. Place this new zip you created on a memory stick and then….
Flash it using twrp or any tool of choice.
8. Close your eyes prey and run the kernel.
Two things can happen.
1. Blank screen nothing happens. Only god can help you, repeat all the steps.
2. Your android starts booting. Start crying of joy
Check in your android if this is indeed the kernel you build. If so time to make some adjustments to your configs or happily enjoy your boosted phone.
Now please remember. If you plan to distribute your kernel that you do the correct steps of accrediting the original programmer and trow the source online. If you use a already custom kernel please respect the hard work of the maker and communicate your plans with him/her.