On 02/06/2015 04:12 PM, Stefan Berger wrote:
it's not that simple unfortunately; if we started to re-order / re-map using dup() the file descriptors then all fd's that make it onto the command line, like those for -netdev and others, also need to be adapted to have that re-ordered fd on the command line.
Correct, and that's what I hope to accomplish by making fd registration enforce that the caller check the return value, to make sure that -netdev is now constructing the command line with the fd the child will see rather than what the parent owns. Yes, it means auditing all existing callers.
Conversely, this currently prevents us from ordering the file descriptors as well, since nothing would work without code change. So ordering the file descriptors cannot currently be done with anything that builds up a QEMU command line. So do we really need to re-order them then as part of this code change?
I think that a pre-req series that orders fds in the child for all callers, independent of adding your new TPM features, will be a good thing in the long run. So I'm currently working on said series. :) -- Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org