On Fri, Feb 14, 2025 at 03:03:20AM -0800, Andrea Bolognani wrote:
On Thu, Feb 13, 2025 at 01:19:53PM -0500, Laine Stump wrote:
The result is that you can now have:
<interface type='vhostuser'> <backend type='passt'/> ... </interface>
Then as long as you also have the following as a subelement of <domain>:
<memoryBacking> <access mode='shared'/> </memoryBacking>
your passt interfaces will benefit from the greatly improved efficiency of a vhost-user data path
The presence of this element is not validated anywhere though, so if you leave it out the network interface will just silently be non-functional. I don't think that makes for a good user experience.
How does passt know where the backing file is located in the first place? It's not passed on its command line, and I didn't spot any logic to hand the information over. This part clearly works, I just don't understand how :)
IIUC the vhost user protocol passes over a pre-opened FD for the memory region(s). With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|