[CRIU] Criu Restore Error

[Cyrill Gorcunov]

On Mon, Mar 23, 2015 at 05:34:26PM +0530, Priyanka Naik wrote:
>    Sir criu supports only Unix 98 PTY only. We have that already configured
>    on the host system but we are not getting whether the guest system
>    supports it though we are booting the guest with the duplicate copy or the
>    kernel copy of the host system. 
>    How can we check whether guest also supports it??

An easy way is to check if there /dev/ptmx present in the container
still this depends on which type of the container you're running.

>    The problem we are thinking is that of :
>    Firstly, when we run the tty command on host, it gives us the number of
>    the terminal in the form of /dev/pty/no and the criu tool is written to
>    restore back the dumped process on that console. (as per the code tty.c)
>    When we type tty command on the guest, it gives us the output as
>    /dev/console. And the other thing that is observed is guest has /dev/pts/

The /dev/console should be supported by criu as well, the problem is looks
like you've to bindmount slave pty peer from the host to the /dev/console
on the guest, as external mount I guess, where master peer should be present
on host system. Take a look on lxc site, they should be doing what you need
i think.

>    folder. Even that folder has ptmx file which according to what I read is
>    Master file. Since the slave files like /dev/pts/no are not present on the
>    guest side the criu source code file tty.c fails to output the restored
>    process on the console.
>    So now :
>    Is there a way to add such /dev/pts/no slaves on guest side? and if yes,
>    then how??

This should be done by a wrapping code. The CRIU itself has nothing to do
with such things, it only operates with resources present on dump time
and manage them on restore.

>    If not is there some way through which we can output the restoring stuff
>    on /dev/console?? 

If I understand you correctly you want to dump with one configuration and
restore with another, no, this won't work in general.

>    Is there some way through which we can change the name of the console so
>    that it will be supported by that criu tool??
>    Another thing I wanted to tell you is, Is there some other way to mount
>    the vdisk.img? Because I m getting error while running partprobe.

It depends on what kind of error you get. qemu-nbd doesn't work?

p.s. please don't stip criu mailing list from CC