On 03/09/2011 08:38 AM, Paolo Bonzini wrote:
On 03/09/2011 03:11 PM, Michael Roth wrote:
In the context of virtagent I would agree. The only complication there
being that a large part of the event-driven code (the async read/write
handlers for instance) is shared between virtagent and the host.
What exactly? The dependencies in 16/16 give:
qemu-tool.o qemu-error.o qemu-sockets.c $(oslib-obj-y) $(trace-obj-y)
$(block-obj-y) $(qobject-obj-y) $(version-obj-y) qemu-timer-common.o
qemu-timer.o
These objs: virtagent.o virtagent-server.o virtagent-common.o
virtagent-transport.o virtagent-manager.o
Are shared by qemu and qemu-va. virtagent.o uses the common timer
infrastructure introduced in patch 3, and
virtagent-transport/virtagent-common use the iohandler stuff from patch 1/2.
On the host, qemu's event loop drives them, and on the guest, qemu-va's
event loop drives them.
Not sure what level of sharing we can maintain with 2 different event
loops. I'm sure it's doable, just not sure what it would end up looking
like.
I should note that initially all the qemu_set_fd_handler() stuff was
wrapped to provide compatibility between separate event loop
implementations in qemu/qemu-va. Sharing the event loop code was a
widely-held consensus from earlier reviews. I'm not sure glib is so nice
that it's worth back-peddling on that. And if we do eventually make
qemu's event loop glib-based, consumers of the common code here would
get migrated over for free.
Compared to other tools, only qemu-sockets.c is added (and timers);
overall it is quite self contained and interfaces well with glib's
GIOChannels, which provide qemu_set_fd_handler-equivalent functionality.
In addition, qemu iohandlers have a lot of unwritten assumptions, for
example on Win32 they only work with sockets and not other kinds of file
descriptors.
Hmm, that could be a problem... It seems like a more general one though,
that might benefit consumers other than virtagent. So if this is
addressed at some point, consumers of the common infrastructure proposed
here would all benefit.
Paolo
