I propose to list here some technologies that have some capability characteristics but ultimatly fail to provide capability benefits.

BSD beside Mach

Apple’s description of the Mach kernel within the OS X system for the Mac seems to describe a capability system. The italic section at the end, however, seems peculiar from our perspective. They seem to say that the ability to send messages on ports is dangerous and must be limited to very trusted programs. From our perspective the issue is not whether bad programs hold port rights, but which port rights they hold. If this is just a misunderstanding of the writer (and reviewers), there may be gold to be mined in OSX. See some earlier Mach notes and this concept map.

From the Kernel Programming Guide: Architecture:

I understand from this that all of BSD and the “I/O Kit” is in everyone’s TCB. From the Mach Overview we hear: It seems clear that this extended kernel all runs in privileged mode. Still it does not yet preclude adding cages for untrusted code which limit their content by lack of “port rights”.

Tasks and Threads is a clear description of concepts and constructs.