Mapping Virtual memory to physical memory

[Mark Milligan <milligan%realtime.bc.ca@localhost>]

A quick question:

Is there a function or api call to get the physical address from a virtual
address?  I am helping port netbsd to an 8260 powerpc and the internal
communications controler cannot handle virtual addresses, it bypassess the
address translation for DMA etc.  So I would like to be able to take the
virtual address of a destination buffer and convert it to a physical address
for the DMA controler.

Ive read the man pages on bus_dma, uvm, kvm and looked thru the pmap.c code and
the closest thing ive found is the pmap_extract() function but it seems like a
internal (to pmap) functon only and dosent seem very usefull.  I could write a
wraper to go around this function but I am hopeing there is a better way.

I know there are a couple of other people ho have worked on 8260 ports out
there, how have you handled this problem?

Thanks in advance.


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Mark Milligan