DragonFly kernel List (threaded) for 2005-11
Re: Copyout to XIO
:I have a question regarding the use of XIO's. It seems that XIO's let
:a thread without process context read another processes's user buffer
:(which should be very handy), but there doesn't seem to be a way for
:that thread to write back into the process's address space, unless
:that process happens to be switched in and we use copyout() the old
:How would a new-style device driver or filesystem implement READ for
:a user process from within its own thread?
All device I/O is eventually going to be converted to a vm_page array
on entry. We're about half way along that goal. Certain higher level
system calls, such as read and write, will have to break large I/O's
into smaller chunks that can be page-listed.
The current use of alternative PMAPs to access another processes address
space will eventually be removed, since its impossible to abstract
that sort of access across a cluster.