user space device drivers

[Greg Freemyer]

On Tue, May 14, 2013 at 4:18 AM, Gergely Buday <gbuday at gmail.com> wrote:
>>> Are there serious user space drivers in Linux? Could you name a few?
>>
>> Printer drivers, scanner drivers, file system drivers etc.
>
> How can I find them? Are they in the kernel source tree?
>

Filesystem drivers would use FUSE.

A fairly long list of those is in the examples section of:

http://en.wikipedia.org/wiki/Filesystem_in_Userspace

Not all of those are Linux FUSE based, so don't assume they are all
Linux filesystems, but many of them are.

Note that a lot of filesystems that originate outside of linux, first
come to linux as FUSE implementations.  They may later be ported to
native kernel modules.  It is a effort vs. reward trade-off.  I
suspect the best known linux FUSE based filesystem is NTFS-3G.  I've
done some performance testing of it based on large files and USB3
connectivity.  I don't see any meaningful performance degradation
compared to EXT4 under the same restrictions.

Greg