> sysctl's use to e.g. read PCBs etc. is really because we don't have
> another "good" way of doing it without groveling /dev/kmem.  (It has
> a side benefit of having an explicit packing routine in the kernel so
> that the information can be send back in an ABI-neutral way.)

Making it an ioctl on /dev/kmem would have brought the same benefits.

> I don't really like how we overload sysctl in this way.  Mach
> messages are a much better way of doing this type of request/response
> operation.  But we don't have Mach messaging, so we overloaded
> sysctl.

Doesn't a dedicated socket address family come close?  (That's a
serious question; I don't know enough about Mach to answer it myself.)
AF_KERN anyone?

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