On Wed, 27 Jun 2012 10:58:01 +0200 Kevin Wolf <kwolf@redhat.com> wrote:
Am 26.06.2012 20:40, schrieb Corey Bryant:
Here is a quick proof of concept (ie untested) patch to demonstrate what I mean. It relies on Cory's patch which converts everything to use qemu_open. It is also still valuable to make the change to qemu_open() to support "/dev/fd/N" for passing FDs during QEMU initial startup for CLI args.
IMHO, what I propose here is preferrable for QMP clients that our current plan of requiring use of 3 monitor commands (passfd, XXXXX, closefd).
Thanks for the PoC.
Two other required updates that I can think of would be:
1) Update change, block_stream, block_reopen, snapshot_blkdev, and perhaps other monitor commands to support receiving fd's via SCM_RIGHTS.
Nevermind my comment. I see that your PoC supports passing nfds for any QMP command.
I'm curious what Kevin's thoughts are on this and the overall approach.
I'm not against introducing this nfd thing as a general feature for QMP commands instead of a separate pass-fd command. It's not obvious to me that everyone would agree with that, so let's CC Luiz at least.
I don't have objections either, but I want to point out two things. First, we've agreed on adding new commands instead of extending existing ones. I feel that not everyone is agreement with this and maybe we could revisit this topic, but in principle new commands should be added. Secondly, this is just a small suggestion, but we're in a point in time where several block commands are being added. I think it's a good moment to think hard how the ideal block API would look like and try to design new commands based on that.