====== RTL8852BE WiFi adapter on Debian 12 Bookworm ======

The Realtek WiFi Network Controller **RTL8852BE** is not supported by the **6.1.0 Linux kernel** shipped with **Debian 12 Bookworm**. In this page you can find the steps required to compile and install the required kernel module and firmware.

  * Disable the **Secure Boot** in BIOS.
  * Compile the **rtw89-dkms** Debian package into a chroot environment.
  * Install the **rtw89-dkms** package into the target host, it will compile and install the kernel modules,
  * Download and install the **rtw8852b_fw-1.bin** firmware.

{{ .:mini_pc_t9plus:ami-bios-secure-boot.jpg?200|Secure Boot in BIOS}}
A **self compiled kernel module** is strictly tied to the running kernel, so **it must be re-compiled** whenever the kernel package is upgraded. The official Debian kernel is properly signed, so it runs even if the **Secure Boot** option is enabled into the BIOS. But the self compiled kernel module is a non-trusted software running at kernel level, so it requires that the Secure Boot into the BIOS to be disabled.

Debian provides the **[[wp>Dynamic Kernel Module Support|Dynamic Kernel Module Support]]**, which automatically recompiles all DKMS modules if a new kernel version is installed. This allows drivers and devices outside of the mainline kernel to continue working after a Linux kernel upgrade

===== Creating the chroot environment =====


It is possible to create a DKMS source package for the **rtw_8852be** kernel module starting from the recent Realtek driver sources. This operation requires the installation of several packages; if you don't want to **clutter the target host**, you can do this task on a different host or into a **chroot environment**.

Using the **debootstrap** command (from the Debian package of the same name) it is possibile to initialize a separate (chroot) environment for this task. The target host will not be cluttered by the packages installed into the chroot environment and the resulting DKMS package can be used on several target hosts. The drawback is that you will consume about 1.2 Gb of disk space.

<code>
mkdir -p /usr/local/src/chroot/dkms
debootstrap bookworm /usr/local/src/chroot/dkms http://deb.debian.org/debian/
</code>

===== Creating the dkms source package into the chroot =====

To enter the chroot environment is as simple as issuing the command:

<code>
chroot /usr/local/src/chroot/dkms
</code>

You exit the chroot using the **exit** command.

Into the chroot install the required packages:

<code>
apt install locales
dpkg-reconfigure locales
apt install dh-dkms debhelper build-essential devscripts git-build-recipe
</code>

Then download the source code of the kernel module and compile the DKMS Debian package:

<code>
cd /usr/local/src
git clone https://github.com/lwfinger/rtw89.git
cd /usr/local/src/rtw89
git clean -xfd
git deborig HEAD
dpkg-buildpackage -us -uc
</code>

The **%%git clean -xfd%%** does a complete cleanup of the source tree. The **git-deborig(1)** script (provided by the **devscripts** Debian packages), creates the **../rtw89_1.0.2.orig.tar.xz** archive from the GIT main branch. The .orig.tar.xz archive is required to build a complete Debian package.

At the end of the process you will find the **../rtw89-dkms_1.0.2-3_all.deb** packages, which is the one you have to install into the target system.

===== Installing the DKMS package into the target system =====

Into the target host you need some packages that are required to build the kernel module from the DKMS sources. You need also to install the Linux headers of the same version of your running kernel:

<code>
apt install dkms linux-headers-6.1.0-25-amd64
</code>

Now you are ready to install the DKMS package, this will automatically compile the binaries of the kernel modules and install them into **/usr/lib/firmware/rtw89/**:

<code>
dpkg -i /usr/local/src/chroot/dkms/usr/local/src/rtw89-dkms_1.0.2-3_all.deb
</code>

If you want to load the kernel module without a reboot, just run the commands:

<code>
depmod -a
modprobe rtw_8852be
</code>

You may encounter a problem if Secure Boot is disabled:

<code>
modprobe: ERROR: could not insert 'rtw_8852be': Key was rejected by service 
</code>

You can inspect the status of Secure Boot with the **mokutil** utility (from the same name Debian package):

<code>
mokutil --sb-state
SecureBoot enabled
</code>

===== Providing the firmware =====

If you have installed the non-free Debian package **firmware-realtek**, the kernel module will automatically load the **/lib/firmware/rtw89/rtw8852b_fw.bin**, as logged by the kernel:

<code>
rtw89_8852be 0000:02:00.0: firmware: failed to load rtw89/rtw8852b_fw-1.bin (-2)
rtw89_8852be 0000:02:00.0: firmware: failed to load rtw89/rtw8852b_fw-1.bin (-2)
rtw89_8852be 0000:02:00.0: Direct firmware load for rtw89/rtw8852b_fw-1.bin failed with error -2
rtw89_8852be 0000:02:00.0: firmware: direct-loading firmware rtw89/rtw8852b_fw.bin
rtw89_8852be 0000:02:00.0: loaded firmware rtw89/rtw8852b_fw.bin
</code>

But this is a non working fall-back, you can confirm that the WiFi adapter is not working:

<code>
ifconfig wlan0 up
iwlist wlan0 scan
wlan0     Interface doesn't support scanning : Network is down
</code>

You can download the required firmware from the **[[https://git.kernel.org/pub/scm/linux/kernel/git/firmware/linux-firmware.git/tree/rtw89/rtw8852b_fw-1.bin|kernel Git repository]]** and save it into **/usr/lib/firmware/rtw89/**; there are no directories for locally installed firmwares.

===== Signal level not reported =====

If everything is working, you can check for available WiFi networks using **iwlist**:

<code>
ifconfig wlan0 up
iwlist wlan0 scan
</code>

The current module (rtw89 1.0.2) does not support the signal level reporting, for every ESSID you see the following:

<code>
Quality=70/70  Signal level=0 dBm
</code>


===== Web References =====

  * **[[https://github.com/lwfinger/rtw89]]**
  * **[[https://easylinuxtipsproject.blogspot.com/p/realtek.html]]**