My understanding is that you shouldn't want to find the physical address that
corresponds to the userspace buffer. The result of such a lookup would be out
of date before it's even returned to you, because another processor could have
swapped the page out. That's why virt_to_phys doesn't work for that case.
If you want to access user memory directly via DMA, you have to make sure it's
locked down, in which case you have to muck about with the page tables anyway,
and you can note the physical address while you're at it.
---- ---- ----
David Woodhouse David.Woodhouse@mvhi.com Office: (+44) 1223 810302
Project Leader, Process Information Systems Mobile: (+44) 976 658355
Axiom (Cambridge) Ltd., Swaffham Bulbeck, Cambridge, CB5 0NA, UK.
finger dwmw2@ferret.lmh.ox.ac.uk for PGP key.
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