If you are a seasoned C programmer, helping GNU Hurd, for instance, with the Rump kernel addon to add NetBSD driver support (please, no blobs) would be a good thing to have.
Yep, C is the Unix and Unix-like ABI, and an odd form of C it's under 9front/plan9's ABI/API too, but this makes the userland much more powerful than the typical permission-isolated Unix system where the user has near no capabilities even for mounting non-external media (by default).
https://www.gnu.org/software/hurd/
You can debug drivers on the fly with gdb, something much more difficult to do under OpenBSD, NetBSD and Linux-(libre).
Also, you can run Hurd inside Hurd, a la chroot. But no root permissions are needed.
https://www.gnu.org/software/hurd/community/gsoc/project_ide...
Yep, C is the Unix and Unix-like ABI, and an odd form of C it's under 9front/plan9's ABI/API too, but this makes the userland much more powerful than the typical permission-isolated Unix system where the user has near no capabilities even for mounting non-external media (by default).