[CRIU] Re: Issues of using CRtools

[Pavel Emelyanov]

On 10/11/2012 09:37 PM, Shinkevich Andrey wrote:
> Dear Pavel!
> Thank you very much for answering my questions.
> Please note:
> 1. When I use the following commands
> ./busyloop00 --outfile=output.txt --pidfile=pid.txt
> sudo crtools dump -c -t 4948
> 
> I do specify '-c' option to leave the process busyloop00 with the pid 4948  running.
> But the process busyloop00 terminates anyway.

There's a bug in documentation :( The truth is in crtools --help output

> 2. Then I run the command
> 
> sudo crtools restore -d -t 4948
> 
> and the porcess with the same pid is restored. Then I kill the process 4948 manually and run the command again:
> sudo crtools restore -d -t 4948
> 
> The restoration fails with the following message:
> 
>   4948: Error (files-reg.c:406): Can't open file on restore: No such file or directory
>   4948: Error (files-reg.c:367): Can't open file output.txt.inprogress: No such file or directory
> Error (cr-restore.c:633): 4948 exited, status=255

That's because on process death the file output.txt.inprogress is removed. Note, that
crtools dumps state of _applications_, not the filesystem they run on.

> If I create an empty file output.txt.inprogress the process is restored OK.

That's good news.

> Best regards,
> Andrey
> 
> 10.10.2012, 16:38, "Pavel Emelyanov" <xemul at parallels.com>:
> 
> On 10/10/2012 04:20 PM, Shinkevich Andrey wrote:
> 
>  Dear Pavel! Thank you for your efforts in developping CRtools!
>  E-mail is the only way I found to contact you.
> 
> Please, keep the mailing list in Cc, other people can also help.
> 
>  I am new in Linux Kernel and trying to test CRtools to see how it works.
>  But I've encountered some issues in running CRtools and ask you for favor to assist me in
>  resolving them. - I run CRtools 2.0 on Ubuntu i86-64 VirtualBox - The Linux kernel has been
>  updated and 'sudo crtools check' ends with the message "Looks Good." - Running CRtools without
>  'sudo' results in "Permission denied" message
> 
> This is kernel requirement. Lots of the APIs we use require root prio.
> 
>  - If I run 'gcalctool &' command from
>  Terminal(tty), and then 'sudo crtools dump -t 7472 -c' the error message appears: "tty.c:156
>  Found slave peer index 0 without correspond master peer"
> 
> That's because you dump only one end of a PTY. This case is not supported yet, but
> we're working on this.
> 
>  - If I run the Calculator from Ubuntu
>  GUI and then run the command 'sudo crtools dump -t 7494 -c', the image files are generated and
>  the process 7494 is killed anyway.
> 
> Read the help carefully. By default crtools kills the processes it dumped, but there's a way
> to override this behavior.
> 
>  - Then the following command 'sudo crtools restore -t 7494' results in forced user logging off
> 
> This can be because X apps may use SysVIPC resources you didn't dump and at the restore stage
> X server may go nuts and act strange. Another thing is that dumping X apps is tricky, since
> part of application state resides on the Xserver side and crtools currently do not handle this.
> 
> If you are familiar with how X works and can participate to the project this will be appreciated.
> 
>  - Additional option '-n uts, ipc' does not help
> 
> Absolutely.
> 
>  1. What is wrong with it and how can I run the CRtools correctly?
> 
> The usecases we've recently worked on include 3 cases
> 
> a) daemons
> b) shell tools (but there are limitations with PTYs and sids. Effectively you can
>    for now only succeed when using the screen app, but it's improving)
> c) containers
> 
> Dumping X apps was not taken into account yet. The demo you might have seen on Yandex
> conference dumped a VNC X _server_, which is not the same as dumping X client (i.e. app).
> 
>  2. Where and how can I download the ZDTM test suite?
> 
> It's in the sources in the test/zdtm directory. Plus reading http://criu.org/ZDTM_Test_Suite
> might help.
> 
>  Thank you! You may respond in Russian if you like. Best regards, Andrey
> 
> Thanks,
> Pavel
>