Comment by zozbot234
Some device classes can be supported in userspace because no matter how an adversarial driver might get the device to misbehave, it cannot possibly break the kernel's security model. This might even apply to some audio devices, depending on how exactly they're hooked up to the rest of your system. But the more typical devices, especially those in your average SoC and those connected to a PCIe bus or the like, have full privileges within the system and will need kernel-level support for the foreseeable future.
Kernel modules absolutely run in kernel space though.
I’ve literally written kernel modules for high speed networking devices that have full access to the memory bus and enumerate pci devices. There’s no userspace or kernel space question here. It’s merely a matter of someone turning this into an easily installable kernel module