Google Calling: Inside Android, the gPhone SDK (O'ReillyNet)

There are other exceptions to this.  For instance I used to work on an embedded system with a
home grown OS.  The home grown OS was created back in 1992, and the original version of the
kernel driver in 1993 before anyone at the company ever heard of Linux.  We decided to create
a new version on new hardware running under Linux.  In response to this we added code to call
the pertinent symbols in the Linux Kernel, but we maintained support for our custom OS.

As far as I can tell this does not magically make this a derivative work of Linux.  There are
a number of other modules I have encountered in the past that have similar origins.