Changes

== ns_last_pid ==

== ns_last_pid ==

In order to restore PID, CRIU uses /proc/sys/kernel/ns_last_pid, which is available in kernel since v3.3(according to [[Upstream_kernel_commits]]). It requires CONFIG_CHECKPOINT_RESTORE to be set and it's enabled in the vast majority of distros. ns_last_pid contains the last pid that was assigned by the kernel. So, when kernel needs to assign a new one, it looks into ns_last_pid, gets last_pid and assigns last_pid+1. To restore PID, criu locks ns_last_pid, writes PID-1 and calls clone().

In order to restore PID, CRIU uses /proc/sys/kernel/ns_last_pid, which is available in kernel since v3.3 (according to [[Upstream_kernel_commits]]). It requires CONFIG_CHECKPOINT_RESTORE to be set and it is enabled in the vast majority of distros. ns_last_pid contains the last pid that was assigned by the kernel. So, when kernel needs to assign a new one, it looks into ns_last_pid, gets last_pid and assigns last_pid+1. To restore PID, criu locks ns_last_pid, writes PID-1 and calls clone().

 

== Example ==

== Example ==

Here is a simple program that shows how to set PID for forked child.

Here is a simple program that shows how to set PID for a forked child.

'''BEWARE! This program requires root. I don't take any responsibility for what this code might do to your system.'''( tested though =) )

'''BEWARE! This program requires root. I don't take any responsibility for what this code might do to your system.'''( tested though =) )

<pre>

<source lang="c">

#include <sys/stat.h>

#include <sys/stat.h>

#include <fcntl.h>

#include <fcntl.h>

     return 0;

     return 0;

}

}

</pre>

</source>