[TUHS] Is there a good, even definitive, list of reimplementations of the Unix kernel? What would good cut-off criteria be?

[John Levine via TUHS]

According to steve jenkin via TUHS <sjenkin at canb.auug.org.au>:
>Was “Wind River” and its VxWorks “Unix-like” or something else?

Something else, I think.  They bought BSDI to get a Unix system.

>Does GNU count, as their HURD kernel has never attained the attributes necessary for wide use?

HURD lost its reason for existing once linux worked since it's also GPL.  I see people poking
at HURD, but nothing serious.  Microkernels are an idea that looks appealing but has never really
worked because they're slow due to all the process switching.