Cruel Kernel Tree for Samsung S10, Note10 devices

Based on samsung sources and android common tree. Supported devices: G970F, G973F, G975F, G977B, N970F, N975F, N976B.

Contributors

ExtremeGrief - for overall improvements, porting maple scheduler
thehacker911 - overall improvements and advices
@bamsbamx - ported boeffla_wakelock_blocker module
Nico (@NicoMax2012) - ported moro sound module

Default settings for BoefflaWLBlocker were taken from HadesKernel. Thanks, corsicanu for you great kernel!

How to install

First of all, TWRP Recovery + multidisabler should be installed in all cases. It's a preliminary step. Next, backup your existing kernel. You will be able to restore it from TWRP Recovery in case of problems.

TWRP

Reboot to TWRP Recovery. Flash boot.img in boot slot.

Heimdall

Reboot to Download Mode.

$ sudo heimdall flash --BOOT boot.img

Franco Kernel Manager

Flash boot.img with FK Manager.

Pin problem (Can't login)

The problem is not in sources. It's due to os_patch_level mismatch with you current kernel (and/or twrp). CruelKernel uses common security patch date to be in sync with the official twrp and samsung firmware. You can check the default os_patch_level in build.mkbootimg.* files. However, this date can be lower than other kernels use. When you flash a kernel with an earlier patch date on top of the previous one with a higher date, android activates rollback protection mechanism and you face the pin problem. It's impossible to use a "universal" os_patch_level because different users use different custom kernels and different firmwares. CruelKernel uses the common date by default in order to suite most of users.

How can you solve the problem? 4 ways:

You can restore your previous kernel and the pin problem will gone
You can check the os_patch_level date of your previous kernel here https://cruelkernel.org/tools/bootimg/ and patch cruel kernel image to the same date. If your previous kernel is nemesis, patch cruel to 2099-12 date.
You can reboot to TWRP, navigate to data/system and delete 3 files those names starts with 'lock'. Reboot. Login, set a new pin. To fix samsung account login, reinstall the app
You can rebuild cruel kernel with os_patch_level that suites you. To do it, you need to add the line os_patch_level="<your date>" to the main.yml cruel configuration. See the next section if you want to rebuild the kernel.
You can do the full wipe during cruel kernel flashing

How to customize the kernel

It's possible to customize the kernel and build it from a web browser. First of all, you need to create an account on GitHub. Next, fork this repository. Switch to the "Actions" tab and activate GitHub Actions. At this step you've got your copy of the sources and you can build it with GitHub Actions. You need to open github actions configuration file and edit it from the browser.

First of all, you need to edit model argument (by default it's G973F) to the model of your phone. You can multiple models. Supported models are: G970F, G973F, G975F, G977B, N970F, N975F, N976B.

Edit model:

    strategy:
      matrix:
        model: [ "G973F" ]

For example, you can add two models:

    strategy:
      matrix:
        model: [ "G973F", "G975F" ]

To alter the kernel configuration you need to edit lines:

    - name: Kernel Configure
      run: |
        ./build config                    \
                model=${{ matrix.model }} \
                name=CRUEL-V3.3           \
                +magisk                   \
                +nohardening              \
                +ttl                      \
                +wireguard                \
                +cifs                     \
                +sdfat                    \
                +ntfs                     \
                +morosound                \
                +boeffla_wl_blocker

You can change the name of the kernel by replacing name=CRUEL-V3 with, for example, name=my_own_kernel. You can remove wireguard from the kernel if you don't need it by changing "+" to "-" or by removing the "+wireguard" line and "\" on the previous line. OS patch date can be changed with os_patch_level=2020-02 argument, the default current date is in build.mkbootimg.G973F file.

Available configuration presets can be found at configs folder. Only the *.conf files prefixed with "cruel" are meaningful. For example:

+magisk - integrates magisk into the kernel. This allows to have root without booting from recovery. Enabled by default.
magisk+canary - integrates canary magisk into the kernel.
always_permit - pin SELinux to always use permissive mode. Required on LOS rom.
always_enforce - pin SELinux to always use enforcing mode.
300hz - increases kernel clock rate from 250hz to 300hz. Potentially can decrease response time. Disabled by default, untested.
1000hz - increases kernel clock rate from 250hz to 1000hz. Potentially can decrease response time. Disabled by default, untested.
bfq - enable bfq I/O scheduler in the kernel.
maple - enable maple I/O scheduler in the kernel.
sdfat - use sdfat for exFAT and VFAT filesystems.
ntfs - enable ntfs filesystem support (read only).
cifs - adds CIFS fs support.
tcp_cubic - use CUBIC as default TCP congestion control.
tcp_westwood - use WestWood as default TCP congestion control.
sched_... - enable various (performance, conservative, ondemand, powersave, userspace) CPU schedulers in the kernel.
ttl - adds iptables filters for altering ttl values of network packets. This helps to bypass tethering blocking in mobile networks.
mass_storage - enable usb mass storage drivers for drivedroid.
wireguard - adds wireguard module to the kernel.
morosound - enable moro sound control module.
boeffla_wl_blocker - enable boeffla wakelock blocker module.
+nohardening - removes Samsung kernel self-protection mechanisms. Potentially can increase the kernel performance. Enabled by default. Disable this if you want to make your system more secure.
nohardening2 - removes Android kernel self-protection mechanisms. Potentially can increase the kernel performance. Don't use it if you don't know what you are doing. Almost completely disables kernel self-protection. Very insecure. (fake_config to shut-up android warning)
size - optimize kernel for size.
nodebug - remove debugging information from the kernel.
noksm - disable Kernel Samepage Merging (KSM).
nomodules - disable loadable modules support (fake_config to shut-up android warning).
noaudit - disable kernel auditing subsystem (fake_config to shut-up android warning).
noswap - disable swapping (fake_config to shut-up android warning).
nozram - disable nozram.
fake_config - Use defconfig for /proc/config.gz Some of the config presets, for example nomodules, noaudit are safe but Android system checks kernel configuration for these options to be enabled and issues the warning "There's an internal problem with your device. Contact your manufacturer for details." in case they are not. This config preset forces default configuration to be in /proc/config.gz This trick allows to pass Android system check and shut up the warning. However, the kernel will use other configuration during build.

For example, you can alter default configuration to something like:

    - name: Kernel Configure
      run: |
        ./build config                    \
                os_patch_level=2020-12    \
                model=${{ matrix.model }} \
                name=OwnKernel            \
                +magisk+canary            \
                +wireguard                \
                +nohardening              \
                +1000hz

After editing the configuration in the browser, save it and commit. Next, you need to switch to the "Actions" tab. At this step you will find that GitHub starts to build the kernel. You need to wait about 25-30 mins while github builds the kernel. If the build is successfully finished, you will find your boot.img in the Artifacts section. Download it, unzip and flash.

To keep your version of the sources in sync with main tree, please look at one of these tutorials:

How to build the kernel locally on your PC

This instructions assumes you are using Linux. Install mkbootimg from osm0sis (https://github.com/osm0sis/mkbootimg), heimdall (if you want to flash the kernel automatically).

# Install prerequisites
# If you use ubuntu or ubuntu based distro then you need to install these tools:
$ sudo apt-get install build-essential libncurses-dev libtinfo5 bc bison flex libssl-dev libelf-dev
# If you use Fedora:
$ sudo dnf group install "Development Tools"
$ sudo dnf install ncurses-devel ncurses-compat-libs bc bison flex elfutils-libelf-devel openssl-devel

# Install mkbootimg
$ wget https://github.com/osm0sis/mkbootimg/archive/master.zip
$ unzip master.zip
$ cd mkbootimg-master
$ sed -i -e 's/-Werror//g' Makefile
$ make
$ sudo mv mkbootimg /usr/local/bin/mkbootimg

# Get the sources
$ git clone https://github.com/CruelKernel/samsung-exynos9820
$ cd samsung-exynos9820
# List available branches
$ git branch -a | grep remotes | grep cruel | cut -d '/' -f 3
# Switch to the branch you need
$ git checkout cruel-v3
# Install compilers
$ git submodule update --init --recursive
# Compile
$ ./build mkimg name=CustomCruel model=G973F +magisk+canary +wireguard +ttl +cifs +nohardening
# You will find your kernel in boot.img file after compilation.
$ ls -lah ./boot.img

# You can automatically flash the kernel with heimdall
# if you connect your phone to the PC and execute:
$ ./build :flash

# Or in a single command (compilation with flashing)
# ./build flash name=CustomCruel model=G973F +magisk+canary +wireguard +ttl +cifs +nohardening

ickyphuz / samsung-exynos9820