tech-kern archive


Re: Introducing non-RAM managed page ("device page")

> The VM subsystem does not fiddle with the MMU.  pmap does.

So, you're defining "the VM subsystem" in such a way that the statement
becomes a tautology.

I suppose that's a self-consistent point of view, but it seems rather
like sophistry to me; I have trouble _not_ seeing the pmap code as,
basically, the MD part of the VM subsystem.  Drawing a line between the
two and saying "I define the VM subsystem as the stuff on *this* side
of this line" seems like a pointless exercise in creating confusing new
terminology by inventing new meanings for relatively well-established

Furthermore, I'm not even sure it's correct.  mmap(), even on devices,
is found in sys/uvm/ and uses the UVM data structures to cooperate with
the rest of UVM when creating and manipulating virtual pages.  Drawing
lines not only between UVM and pmap, but between parts of UVM and other
parts of UVM, and defining "the VM subsystem" as stuff on only one side
of that line, is getting byzantine for no point.

But, well, if that's what floats your boat, go ahead.  I would suggest
you prepare yourself for being widely misunderstood, though.

/~\ The ASCII                             Mouse
\ / Ribbon Campaign
 X  Against HTML      

Home | Main Index | Thread Index | Old Index