Add Kali Linux compiling how-to

Compile-firmware.md

@@ -222,3 +222,70 @@ If you want to have all these commands in one go, go to https://github.com/GullC
 - [Linux Aarch64 gcc-arm-none-eabi-9-2020-q2-update-aarch64-linux.tar.bz2](https://developer.arm.com/-/media/Files/downloads/gnu-rm/9-2020q2/gcc-arm-none-eabi-9-2020-q2-update-aarch64-linux.tar.bz2?revision=7166404a-b4f5-4598-ac75-e5f8b90abb09&rev=7166404ab4f54598ac75e5f8b90abb09&hash=07EE5CACCCE77E97A1A8C049179D77EACA5AD4E5)
 - [Toolsets archive](https://developer.arm.com/downloads/-/gnu-rm)
 - [Compilation error after changing toolsets](https://github.com/portapack-mayhem/mayhem-firmware/issues/420)
+
+
+# Compiling Mayhem Firmware on Kali Linux
+Tested at 21. Sept. 2024 on Kali 2024.3 kali-rolling
+Should work for any Debian based Distribution, see comments.
+
+## Download and install dependencies
+```
+sudo apt update
+sudo apt install git tar bzip2 lz4 wget curl cmake python3 python3-setuptools python3-distutils-extra python3-yaml dfu-util hackrf
+```
+
+In many distributions the tool `hackrf` is provided, but outdated because of the release policy. Kali is rolling release, so does not follow this restrictions.
+If you have a R9 or newer HackRF and need a newer version, I recommended to download and compile it by yourself. Source: https://github.com/greatscottgadgets/hackrf
+
+## Download and install the ARM toolchain
+If you use another Version as 9.2.1, the mayham cmake warns you:
+> WARNING: Compiler version mismatch, please use the official compiler version 9.2.1 when sharing builds! Current compiler version: 13.2.1
+
+It might compile. From other projects, as Proxmark3 or Chameleon Ultra, we know the gcc-arm-none-eabi in version 13 (provided by various distributions) creates a bigger firmware image, which won't fit into the memory. Even if it compiles without error, the firmware file is useless.
+
+```
+sudo mkdir /opt/build
+sudo chmod $USER:$(id -gn $USER) /opt/build
+cd /opt/build
+wget https://developer.arm.com/-/media/Files/downloads/gnu-rm/9-2019q4/gcc-arm-none-eabi-9-2019-q4-major-x86_64-linux.tar.bz2
+mkdir armbin
+tar --strip=1 -xjvf gcc-arm-none-eabi-9-2019-q4-major-x86_64-linux.tar.bz2 -C armbin
+```
+
+I recommend to adjust the user rights at the first possible moment. Work as root as less as possible.
+If more than one person works in the system, feel free to set the group to something more generic. For example `src` or `staff`.
+
+Source for the newest toolcain: https://developer.arm.com/downloads/-/arm-gnu-toolchain-downloads
+Source for deprecated toolchain: https://developer.arm.com/downloads/-/gnu-rm
+
+
+### Set toolchain as default
+```
+echo 'PATH=/opt/build/armbin/bin:/opt/build/armbin/lib:$PATH' >> ~/.zshrc
+source ~/.zshrc
+```
+
+Kali Linux uses [ZSH](https://en.wikipedia.org/wiki/Z_shell) as default shell. On [Debian](https://wiki.debian.org/Shell) is Bash the default shell, so if you are using Debian or changed the default shell, you need to pipe the echo into ~/.bashrc (or the related [rc file](https://en.wikipedia.org/wiki/Configuration_file))
+
+## Get the Firmware from Github
+```
+cd ~
+mkdir git
+cd git
+git clone https://github.com/portapack-mayhem/mayhem-firmware/ --recurse-submodules
+```
+
+Personal Note:
+> You could work at any place, for example `/opt`. The [FHS](https://en.wikipedia.org/wiki/Filesystem_Hierarchy_Standard) says `/usr/src` wold be the right place for source codes. But this would be in `/` and most systems I know got roundabout 20 to 50 GB for `/` and several 100 GB for `/home`, so I decide to work with git in /home.
+
+
+## Build the firmware
+```
+cd ~/git/mayhem-firmware
+mkdir build
+cd build
+cmake ..
+make clean && make
+```
+
+For the first compile `make clean &&` is not necessary. But if the compilation stops of any reason, you need to use clean. If nothing is there, it won't hurt.