hcitool does see something, but bluetoothctl still does not $ hcitool scan Scanning ... 41:BB:00:D0:D3:D8 Baseus Bowie WM02

Sorry I did not provide enough info. I am using Debian bookworm, completely updated as far as I know, and it looks like you might be using Ubuntu. Maybe I needed to use bookworm-backports as you suggested; it looks like a newer version there. I've actually found another way to do what I was trying to do with v4l2loopback and don't need it anymore, but thanks for looking at it. Here is some output that you asked for: _ _ _ /_\ _ _ _ __ | |__(_)__ _ _ _ / _ \| '_| ' \| '_ \ / _` | ' \ /_/ \_\_| |_|_|_|_.__/_\__,_|_||_| v25.5.1 for Renegade running Armbian Linux 6.12.32-current-rockchip64 Packages: Debian stable (bookworm) IPv4: (LAN) 10.0.44.17, 192.168.4.254 (WAN) 107.77.207.5 Performance: Load: 50% Up time: 0 min Memory usage: 13% of 968M CPU temp: 36°C Usage of /: 13% of 30G Commands: Configuration : armbian-config Monitoring : htop Last login: Sat Jul 5 20:21:20 2025 from 10.0.44.1 pburt@gato:~$ cat /etc/debian_version 12.11 pburt@gato:~$ apt-cache policy v4l2loopback-dkms v4l2loopback-dkms: Installed: (none) Candidate: 0.12.7-2 Version table: 0.13.2-1~bpo12+1 100 100 http://deb.debian.org/debian bookworm-backports/main arm64 Packages 100 http://deb.debian.org/debian bookworm-backports/main armhf Packages 0.12.7-2 500 500 http://deb.debian.org/debian bookworm/main arm64 Packages 500 http://deb.debian.org/debian bookworm/main armhf Packages pburt@gato:~$ sudo apt install v4l2loopback-dkms [sudo] password for pburt: Reading package lists... Done Building dependency tree... Done Reading state information... Done The following additional packages will be installed: dkms Suggested packages: menu Recommended packages: fakeroot The following NEW packages will be installed: dkms v4l2loopback-dkms 0 upgraded, 2 newly installed, 0 to remove and 0 not upgraded. Need to get 86.0 kB of archives. After this operation, 308 kB of additional disk space will be used. Do you want to continue? [Y/n] Get:1 http://deb.debian.org/debian bookworm/main arm64 dkms all 3.0.10-8+deb12u1 [48.7 kB] Get:2 http://deb.debian.org/debian bookworm/main arm64 v4l2loopback-dkms all 0.12.7-2 [37.2 kB] Fetched 86.0 kB in 1s (119 kB/s) Selecting previously unselected package dkms. (Reading database ... 71668 files and directories currently installed.) Preparing to unpack .../dkms_3.0.10-8+deb12u1_all.deb ... Unpacking dkms (3.0.10-8+deb12u1) ... Selecting previously unselected package v4l2loopback-dkms. Preparing to unpack .../v4l2loopback-dkms_0.12.7-2_all.deb ... Unpacking v4l2loopback-dkms (0.12.7-2) ... Setting up dkms (3.0.10-8+deb12u1) ... Setting up v4l2loopback-dkms (0.12.7-2) ... Loading new v4l2loopback-0.12.7 DKMS files... Building for 6.12.32-current-rockchip64 Building initial module for 6.12.32-current-rockchip64 Error! Bad return status for module build on kernel: 6.12.32-current-rockchip64 (aarch64) Consult /var/lib/dkms/v4l2loopback/0.12.7/build/make.log for more information. dpkg: error processing package v4l2loopback-dkms (--configure): installed v4l2loopback-dkms package post-installation script subprocess returned error exit status 10 Errors were encountered while processing: v4l2loopback-dkms E: Sub-process /usr/bin/dpkg returned an error code (1) pburt@gato:~$ cat /var/lib/dkms/v4l2loopback/0.12.7/build/make.log DKMS make.log for v4l2loopback-0.12.7 for kernel 6.12.32-current-rockchip64 (aarch64) Sun Jul 6 06:20:57 PM CDT 2025 Building v4l2-loopback driver... make -C /lib/modules/6.12.32-current-rockchip64/build M=/var/lib/dkms/v4l2loopback/0.12.7/build modules make[1]: Entering directory '/usr/src/linux-headers-6.12.32-current-rockchip64' CC [M] /var/lib/dkms/v4l2loopback/0.12.7/build/v4l2loopback.o /var/lib/dkms/v4l2loopback/0.12.7/build/v4l2loopback.c: In function ‘vidioc_querycap’: /var/lib/dkms/v4l2loopback/0.12.7/build/v4l2loopback.c:717:9: error: implicit declaration of function ‘strlcpy’; did you mean ‘strncpy’? [-Werror=implicit-function-declaration] 717 | strlcpy(cap->driver, "v4l2 loopback", sizeof(cap->driver)); | ^~~~~~~ | strncpy cc1: some warnings being treated as errors make[3]: *** [scripts/Makefile.build:229: /var/lib/dkms/v4l2loopback/0.12.7/build/v4l2loopback.o] Error 1 make[2]: *** [/usr/src/linux-headers-6.12.32-current-rockchip64/Makefile:1945: /var/lib/dkms/v4l2loopback/0.12.7/build] Error 2 make[1]: *** [Makefile:224: __sub-make] Error 2 make[1]: Leaving directory '/usr/src/linux-headers-6.12.32-current-rockchip64' make: *** [Makefile:43: v4l2loopback.ko] Error 2 pburt@gato:~$

I am having trouble with my SPI LCD, which uses driver panel-mipi-dbi It works great when I use a minimal Armbian image, but with a desktop image it doesn't work. This is because package "plymouth" does something in the ko loading order: it loads panel-mipi-dbi too early. Plymouth provides a graphical boot animation. The driver depends on a binary file /lib/firmware/panel-mipi-dbi-spi.bin (but the file name could change depending on the DTS) At boot time, I saw that the panel-mipi-dbi.ko is loaded BEFORE the EXT4 in the microSD is mounted... and the binary file is not in the initrd.img-version (checked with lsinitramfs) Is it possible to add something in /etc/initramfs-tools/ to include /lib/firmware/panel-mipi-dbi-spi.bin ? With my Raspberry Pi (Raspbian) I don't have this problem, because the panel-mipi-dbi driver is loaded AFTER EXT4-fs (and it also uses plymouth)

I believe you likely have an outdated version of the package. Here is the latest changelog entry for Ubuntu Noble. If you are using an older version, consider upgrading. If you are on bookworm you might want to consider the backports pocket. Or you can think about simply applying above patch locally. Next time, please provide relevant information and logs in your first post. Don't make us guess.

please give the output of "apt policy v4l2loopback-dkms" FWIW, installation worked just fine right now on my BPi M2+ $ sudo apt reinstall v4l2loopback-dkms Reading package lists... Done Building dependency tree... Done Reading state information... Done 0 upgraded, 0 newly installed, 1 reinstalled, 0 to remove and 5 not upgraded. Need to get 30.6 kB of archives. After this operation, 0 B of additional disk space will be used. Get:1 http://ports.ubuntu.com noble/universe armhf v4l2loopback-dkms all 0.12.7-2ubuntu5 [30.6 kB] Fetched 30.6 kB in 1s (20.8 kB/s) (Reading database ... 143046 files and directories currently installed.) Preparing to unpack .../v4l2loopback-dkms_0.12.7-2ubuntu5_all.deb ... Deleting module v4l2loopback-0.12.7 completely from the DKMS tree. Unpacking v4l2loopback-dkms (0.12.7-2ubuntu5) over (0.12.7-2ubuntu5) ... Setting up v4l2loopback-dkms (0.12.7-2ubuntu5) ... Loading new v4l2loopback-0.12.7 DKMS files... Building for 6.12.30-current-sunxi Building initial module for 6.12.30-current-sunxi Done. v4l2loopback.ko: Running module version sanity check. - Original module - No original module exists within this kernel - Installation - Installing to /lib/modules/6.12.30-current-sunxi/updates/dkms/ depmod....