[$] Copyright notices (or the lack thereof) in kernel code

The practice of requiring copyright assignments for contributions tofree-software projects has been in decline for years; the GNU Binutilsproject may be thelatest domino to fall in that regard. The Linux kernel project,unlike some others, has always allowed contributors to retain their copyrights,resulting in a code base that has widely distributed ownership. In such aproject, who owns the copyright to a given piece of code is not alwaysobvious. Somedevelopers (or their employers) are insistent about the placement ofcopyright notices in the code to document their ownership of parts of thekernel. A series of recent discussions within the Btrfs subsystem, though,has made it clear that there is no project-wide policy on when thesenotices are warranted - or even acceptable.