On 07/20/2011 05:42 AM, Anthony Liguori wrote:
I suspect a normal uart is a bad use case for this.
The THR can only hold a single value, a guest is not supposed to write
to the THR again until the THRE flag in the LSR is set which indicates
that the THR is empty.
In fact, when THRE is raised, the device emulation should raise an
interrupt and that's what should trigger the guest to write another
value to the THR.
So in practice, I don't see how it would work without relying on some
specific behavior of the current Linux uart guest code.
But that said, I think this is an interesting mechanism. I'd be
curious how well it worked for VGA planar access which is what the
current coalesced I/O is most useful for.
Probably the interesting use case is to forward an entire BAR to a
separate process or thread, perhaps implemented in the kernel. However
synchronization will be an issue - a PCI read is supposed to flush all
pending PCI writes, and this is hard to enforce when the socket
consumers are out of process.
--
error compiling committee.c: too many arguments to function
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