Communications kernel -> userland

[Terry Lambert]

Robert Watson wrote:
> Of these approaches, my favorite are writing directly to a file, and using
> a psuedo-device, depending on the requirements.  They have fairly
> well-defined security semantics (especially if you properly cache the
> open-time credentials in the file case).  I don't really like the Fifo
> case as it has to re-look-up the fifo each time, and has some odd blocking
> semantics.  Sockets, as I said, involve a lot of special casing, so unless
> you're already dealing with network code, you probably don't want to drag
> it into the mix.  If you're creating big new infrastructure for a feature,
> I suppose you could also hook it up as a first class object at the file
> descriptor level, in the style of kqueue.  If it's relatively minor event
> data, you could hook up a new kqueue event type.  You could also just use
> a special-purpose system call or sysctl if you don't mind a lot of context
> switching and lack of buffering.

I like setting the PG_G bit on the page involved, which maps it
into the address space of all processes.  8-).

-- Terry