[CRIU] about checkpointing lxc container

[Pavel Emelyanov]

On 10/10/2013 04:54 PM, Xinyang Ge wrote:
>> It means there is some socket in container which we don't support yet
>> (maybe raw sockets or something). Try to play with "ss" utility inside
>> container to figure out which sockets are present there.
>>
>> Also, you may start "criu dump" with -v4 option and post the output
>> here, as far as I remember we collect information about sockets
>> and print it.
> 
> I figured out it was udev that caused obstacles from checkpointing. I
> stopped it and another error occurs:
> 
> (00.093895) Error (tty.c:221): tty: Unexpected format on path /dev/lxc/tty4

Ah, this is a terminal, that lxc tool bind-mounts from host into container.
There's a pair end to this /dev/lxc/tty4 sitting somewhere outside of the
container.

This is something we call "external resource" -- an object, that links
container with the outer world (typically with the host). By default CRIU
should only dump containers without such things, but sometimes we have to
manually specify exceptions to that rule.

The terminal you're having problem with is such -- we should somehow explain
to CRIU, that this terminal is "external" to make CRIU dump only one half
of it and on restore get one from lxc container setup machinery.


Hope this explanation helps :)

> I attached the -v4 output in this email. Could you please take a look
> and give us some suggestions on how to handle it?
> 
> Xinyang

Thanks,
Pavel