From: Matthew Grooms <>
Date: Sun, 30 Apr 2023 21:41:36 UTC
On 4/29/23 06:17, void wrote:
> Hi,
> Where can I read up about the recently introduced BHYVE_SNAPSHOT ?
> I can only find terse information about what it does (in man 5 src.conf)
> but not about how to use it and/or why.

This began as sponsored student work with the Politehnica University of 
Bucharest back in 2016 with an eye toward developing Live MIgration as a 
feature. The initial bhyve save/restore patch was committed back in 2020 ...

Student projects related to bhyve continued until last year, but we gave 
up due to there being such a massive accumulation of patches with no 
path to getting them committed. We tried reaching out to project 
maintainers and the FreeBSD foundation alike for support and feedback, 
but there seems to be little to no interest. There have also been 
attempts by companies that rely on these features to and get them 
improved and committed. Unfortunately they don't appear to be having 
much luck either ...

Would you like to see support for VM snapshots in the generic kernel? 
How about support for saving/restore checkpoints using QCOW2, VMDK via 
libvdsk? How about support for warm or live migration? How about USB 
device pass-through? There are experimental patches for all these 
features that were developed by students at UPB. In a lot of cases, 
there are open reviews that have been waiting on feedback for ages. Here 
is a a presentation given by Elena from UPB just last month at the 
FreeBSD devsumit in Tokyo ...

The case is quite plain. I'm not sure what the solution is to this 
problem. I'd love to hear feedback from the community about how I've got 
this completely wrong and how the course could be corrected. That would 
be something.