Installation

criu is an utility to checkpoint/restore a process tree.

Tools installation

Get the latest release:

Tarball:	criu-4.0.tar.gz
Version:	4.0 "CRIUDA"
Released:	20 Sep 2024
GIT tag:	v4.0

Alternatively, use git.criu.org git repository. Clone this repo to test new functionality.

Before building, make sure you have C bindings for Google's Protocol Buffers installed. In an RPM-based world this is the protobuf-c-devel package, and on Debian and derivatives, libprotobuf-c0-dev. If for some reason there is no appropriate package for your system available, just install Google's Protocol Buffer from the source tarball. The protocol buffer library can be found at http://code.google.com/p/protobuf/, while protocol buffer C binding can be found at http://code.google.com/p/protobuf-c/.

Then run make in the sources root. Please, note, that the tool only supportes x86_66 and ARM architectures.

Kernel configuration

The v3.11 upstream kernel already has all the required functionality merged. Make sure you have the following options turned on:

• General setup -> Checkpoint/restore support (CONFIG_CHECKPOINT_RESTORE)
• General setup -> Namespaces support (CONFIG_NAMESPACES)
• General setup -> Namespaces support -> PID namespaces (CONFIG_PID_NS)
• General setup -> open by fhandle syscalls (CONFIG_FHANDLE)
• General setup -> Enable eventfd() system call (CONFIG_EVENTFD)
• General setup -> Enable eventpoll support (CONFIG_EPOLL)
• File systems -> Inotify support for userspace (CONFIG_INOTIFY_USER)
• Executable file formats -> Emulations -> IA32 Emulation (CONFIG_IA32_EMULATION)
• Networking support -> Networking options -> Unix domain sockets -> UNIX: socket monitoring interface (CONFIG_UNIX_DIAG)
• Networking support -> Networking options -> TCP/IP networking -> INET: socket monitoring interface (CONFIG_INET_DIAG)
• Networking support -> Networking options -> TCP/IP networking -> INET: socket monitoring interface -> UDP: socket monitoring interface (CONFIG_INET_UDP_DIAG)
• Networking support -> Networking options -> Packet socket -> Packet: sockets monitoring interface (CONFIG_PACKET_DIAG)
• Networking support -> Networking options -> Netlink socket -> Netlink: sockets monitoring interface (CONFIG_NETLINK_DIAG)

Note you might have to enable

• General setup -> Configure standard kernel features (expert users) (CONFIG_EXPERT)

option, which depends on

• General setup -> Embedded system (CONFIG_EMBEDDED)

(welcome to Kconfig reverse chains hell).

For some usage scenarios there is an ability to track memory changes and produce incremental dumps. Need to enable

• Processor type and features -> Track memory changes (CONFIG_MEM_SOFT_DIRTY)

In the future we can start working on some new kernel stuff for CRIU. In that case we will first put this into a repository at linux-cr.git (linux-cr-rpi.git for Raspberry Pi), so that anyone can checkout the latest branch and compile the kernel.

iproute2

The iproute2 tool version 3.5.0 or higher is needed for dumping network namespaces. The latest one can be cloned from the iproute2. It should be compiled and a path to ip is written in the environment variable CR_IP_TOOL.

Checking how it works

First thing to do is to run

# criu check --ms

At the end it should say "Looks OK", if it doesn't the messages on the screen explain what functionality is missing. If you're using our custom kernel, then the --ms option should not be used, in this case CRIU would check for all the kernel features to work.

You can then try running the ZDTM Test Suite which sits in the tests/zdtm/ directory.

There's a known issue with BTRFS spoiling dev_t values for files and sockets! Not all tests will work on it.

Using CR tools

Please see Usage and Advanced usage, as well as Category:HOWTO.