Does anyone know of some cheap linux-incompatible hardware i could use to practice writing kernel-drivers for?
Everything I have currently works oob with linux, or is made by nvidia (graphics is a bit too crazy for me for now)
@lucydev Those cheap WiFi 6 dongles on AliExpress? Quite a few of them have chips that are either partially supported (Bluetooth only) or unsupported in the kernel. If you get a few different <$5 ones you're likely to have at least some that don't work OOTB.
@joepie91 do you have a specific example you could drop here as a reply? I looked around but so far ive only found some with chipsets supported by the kernel
that sounds interesting!
@lucydev Sure - an example would be 0bda:b851, which is an RTL8821CU; it does have a Bluetooth driver, but not a WiFi driver (at least last time I checked).
@joepie91 there is a barely documented driver from Realtek for the RTL8821CU in the source tree (https://github.com/torvalds/linux/blob/master/drivers/net/wireless/realtek/rtw88/rtw8821cu.c). Would you be able to supply a device/model name or possibly an aliexpress link so i can get my hands on the hardware? Sadly, I wasn't able to find the device that corresponds to ID 0bda:b851 ;-;
Maybe I can try finding out what the issue is and hack a bit on the driver. It's entirely possible, that the driver just doesn't recognize the usb device ID, since they have a hardcoded list of device IDs and 0xb851 isn't contained (see attached screenshot).
I could also make a patch and send it to ya, if you're interested in testing the theory. Iterating would be easier with the actual hardware tho 
@lucydev This is the 0bda:b851 device that I have: https://www.aliexpress.com/item/1005006960284140.html
I also have https://www.aliexpress.com/item/1005005362858380.html which at least on latest NixOS stable does not seem to be detected, and 2 years ago someone else reported that it wasn't supported: https://www.reddit.com/r/openSUSE/comments/12hcqxb/i_have_trouble_getting_this_bluetooth_adapter_to/
hey @joepie91,
itll take until the 20th/22nd before the dongle arrives, and i am on vacation the week after. If you want, you can apply my patch to linux mainline and test it out yourself: https://gitlab.com/-/snippets/4780651
@joepie91 thanks for the link!
Yeah that checks out. This driver has a very short commit history, the earliest being the inclusion based on some out-of-tree source to support the chipset in December 2022.