I was one of the early users of seL4 and am still a named author on the seL4 manual. It's quite possible that things have changed/improved over the last few ye

I was one of the early users of seL4 and am still a named author on the seL4 manual. It's quite possible that things have changed/improved over the last few years, but when I was working on it, I found the programming environment to be, very, very difficult. The capability system suffers from several circular dependencies (e.g splitting up memory capabilities required cnode capabilities, making cnode capabilities required memory capabilities). And the userspace environment is very bare, you have to manage your own page-tables, and your own capabilities. That said, it is also very powerful if you want to write fast, secure, embedded programs, which is what it was really designed for. I'm pretty sure they wrote a device driver for a network card as part of one of the projects, but I don't know if it ever made it out the door. I'm sure you could ask the current team to see if they did and if they would make it open. You never know, you might get lucky.