Re: [Qemu-devel] about post copy recovery

[Li, Liang Z]

> * Li, Liang Z (address@hidden) wrote:
> >
> > Hi David,
> >
> > I remembered some guys wanted to solve the issue of post copy recovery
> when network broken down, do you know latest status?
> 
> Hi Liang,
>   Yes, Haris looked at it as part of GSoC, the latest version is what was 
> posted:
> 
> https://lists.nongnu.org/archive/html/qemu-devel/2016-08/msg03468.html
> 
> I've not done any work on it since then;  there are a couple of hard problems
> to be solved.  The simpler is making sure that we always correctly detect a
> migration error due to networking (rather than some other non-recoverable
> error); there's lots of migration code that doesn't check for a file error
> straight away and only hits the error code later on when it's too late to
> recover.
> 
> The harder problem is that we often end up with the case where the main
> thread is blocked trying to access postcopied-RAM, e.g. an emulated
> network driver tries to write an incoming packet to guest RAM but finds the
> guest RAM hasn't arrived yet.
> With the main thread blocked it's very difficult to recover - we can't issue 
> any
> commands to trigger the recovery and even if we could we'll have to be very
> careful about what things those commands need the main thread to do.
> 
> Dave

Thanks for your information!
I will take a look first, maybe get back to you later.

Liang