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criu(8): massive man page update

Browse Source 
This is an attempt to cleanup the man page. I am very sorry this comes
in this one big patch. Here are the changes:

1. Use *BOLD* for literals, 'ITALIC' for arguments (variable
substituions)

2. Do not use <> for arguments, as they are already marked so (italic)

3. Remove details about "criu exec" and remote syscalls execution;
   add note that it's obsoleted by Compel.

4. Some descriptions are shrunk, some made longer, many are rephrased.

5. Formatting: use second-level lists (*value*:::) where appropriate
   (mostly instead of bulleted lists of values).

6. Properly show comma-separated lists of arguments (with second pair
   of [] and ...

7. Proper use of terms 'option' and 'argument' (*--option* 'argument').

8. Other fixes to formatting and English (such as missing a/the articles).

...

98. Change author to be "the CRIU team".

99. Update copyright years, copyright holder is Parallels Holdings.

[v2: rebase]

Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Kir Kolyshkin <kir@openvz.org>
Reviewed-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>
This commit is contained in:
Kir Kolyshkin
2016-09-23 12:08:14 -07:00
committed by Pavel Emelyanov
parent 4edc7c9cb2
commit 69c79bb500
1 changed files with 194 additions and 228 deletions
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422
Documentation/criu.txt
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@@ -9,28 +9,27 @@ criu - checkpoint/restore in userspace
SYNOPSIS SYNOPSIS
-------- --------
*criu* '<command>' ['options'] *criu* 'command' ['option' ...]
DESCRIPTION DESCRIPTION
----------- -----------
*criu* is a tool for checkpointing and restoring running applications. *criu* is a tool for checkpointing and restoring running applications.
It does this by saving their state as a collection of files (see the 'dump' It does this by saving their state as a collection of files (see the *dump*
command) and creating equivalent processes from those files (see the 'restore' command) and creating equivalent processes from those files (see the *restore*
command). The restore operation can be performed at a later time, command). The restore operation can be performed at a later time,
on a different system, or both. on a different system, or both.
OPTIONS OPTIONS
------- -------
The options are depending on the '<command>' *criu* run with.
Common options Common options
~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~
Common options are applied to any '<command>'. Common options are applicable to any 'command'.
*-v*['<num>'|*v*...]:: *-v*['num'|*v*...]::
Set logging level to '<num>'. The higher the level, the more output Set logging level to 'num'. The higher the level, the more output
is produced. Either numeric values or multiple *v* can be used. is produced. Either numeric values or multiple *v* can be used.
+ +
The following levels are available: The following levels are available:
@@ -43,74 +42,74 @@ The following levels are available:
* *-v4*, *-vvvv* * *-v4*, *-vvvv*
lots of debug. lots of debug.
*--pidfile* '<file>':: *--pidfile* 'file'::
Write root task, service or page-server pid into a '<file>'. Write root task, service or page-server pid into a 'file'.
*-o*, *--log-file* '<file>':: *-o*, *--log-file* 'file'::
Write logging messages to '<file>'. Write logging messages to 'file'.
*--log-pid*:: *--log-pid*::
Write separate logging files per each pid. Write separate logging files per each pid.
*-D*, *--images-dir* '<path>':: *-D*, *--images-dir* 'path'::
Use path '<path>' as a base directory where to look for dump files set. Use 'path' as a base directory where to look for sets of image files.
*--prev-images-dir* '<path>':: *--prev-images-dir* 'path'::
Use path '<path>' as a parent directory where to look for dump files set. Use 'path' as a parent directory where to look for sets of image files.
This make sense in case of increment dumps. This option makes sense in case of incremental dumps.
*-W*, *--work-dir* '<dir>':: *-W*, *--work-dir* 'dir'::
Use directory '<dir>' for putting logs, pidfiles and statistics. If not Use directory 'dir' for putting logs, pidfiles and statistics. If not
specified, '<path>' from *-D* option is taken. specified, 'path' from *-D* option is taken.
*--close* '<fd>':: *--close* 'fd'::
Close file with descriptor '<fd>' before any actions. Close file descriptor 'fd' before performing any actions.
*-L*, *--libdir* '<path>':: *-L*, *--libdir* 'path'::
Path to a plugins directory. Path to plugins directory.
*--action-script* '<SCRIPT>':: *--action-script* 'script'::
Add an external action script. Add an external action script to be executed at certain stages.
The environment variable *CRTOOLS_SCRIPT_ACTION* contains one of the The environment variable *CRTOOLS_SCRIPT_ACTION* is available
actions: to the script to find out which action is being executed, and
* *pre-dump* its value can be one of the following:
run an action prior to beginning a *dump* *pre-dump*:::
run prior to beginning a *dump*
* *post-dump* *post-dump*:::
run an action upon *dump* completion; run upon *dump* completion
* *pre-restore* *pre-restore*:::
run an action prior to beginning a *restore* run prior to beginning a *restore*
* *post-restore* *post-restore*:::
run an action upon *restore* completion; run upon *restore* completion
* *network-lock* *network-lock*:::
lock network in a target network namespace; run to lock network in a target network namespace
* *network-unlock* *network-unlock*:::
unlock network in a target network namespace; run to unlock network in a target network namespace
* *setup-namespaces* *setup-namespaces*:::
run an action once root task just been created run once root task just been created
with required namespaces, note it is early stage with required namespaces. Note it is an early stage
on restore nothing were restored yet except namespaces of restore, when nothing is restored yet except for namespaces
themselves. themselves
*-V*, *--version*:: *-V*, *--version*::
Print program version and exit. Print program version and exit.
*-h*, *--help*:: *-h*, *--help*::
Print a commands list and exit. The commands list is very Print some help and exit.
short one just for overview and does not match this manual.
*pre-dump* *pre-dump*
~~~~~~~~~~ ~~~~~~~~~~
Launches that named pre-dump procedure, where *criu* does snapshot of Performs the pre-dump procedure, during which *criu* creates a snapshot of
memory changes since previous pre-dump. Also *criu* forms fsnotify memory changes since the previous *pre-dump*. Note that during this
cache which speedup *restore* procedure. *pre-dump* requires at least *criu* also creates the fsnotify cache which speeds up the *restore*
*-t* option (see *dump* below). Optionally *page-server* options procedure. *pre-dump* requires at least *-t* option (see *dump* below).
may be specified. In addition, *page-server* options may be specified.
*--track-mem*:: *--track-mem*::
Turn on memory changes tracker in the kernel. If the option is Turn on memory changes tracker in the kernel. If the option is
@@ -118,47 +117,47 @@ may be specified.
*dump* *dump*
~~~~~~ ~~~~~~
Starts a checkpoint procedure. Performs a checkpoint procedure.
*-t*, *--tree* '<pid>':: *-t*, *--tree* 'pid'::
Checkpoint the whole process tree starting from '<pid>'. Checkpoint the whole process tree starting from 'pid'.
*-R*, *--leave-running*:: *-R*, *--leave-running*::
Leave tasks in running state after checkpoint instead of killing them. This Leave tasks in running state after checkpoint, instead of killing. This
option is pretty dangerous and should be used if and only if you understand option is pretty dangerous and should be used only if you understand
what you are doing. what you are doing.
+ +
If task is about to run after been checkpointed it can modify TCP connections, Note if task is about to run after been checkpointed, it can modify
delete files and do other dangerous actions. So that *criu* itself can not TCP connections, delete files and do other dangerous actions. Therefore,
guarantee that the next *restore* action will not fail. Most likely if a user *criu* can not guarantee that the next *restore* action will succeed.
starts *criu* with this option passed at least the file system snapshot must be Most likely if this option is used, at least the file system snapshot
done with help of 'post-dump' script. must be made with the help of *post-dump* action script.
+ +
In other words, do not use it until really needed. In other words, do not use it unless really needed.
*-s*, *--leave-stopped*:: *-s*, *--leave-stopped*::
Leave tasks in stopped state after checkpoint instead of killing them. Leave tasks in stopped state after checkpoint, instead of killing.
*-x*, *--ext-unix-sk* ['<inode>',<inode>']:: *-x*, *--ext-unix-sk* ['inode'[,'inode'...]]::
Dump external unix sockets. Optionally passing '<inode>' (or comma separated Dump external unix sockets. Optionally passing a comma-separated
series) it assigns inodes which allowed for one sided dump. list of inodes to allow a one sided dump for those.
*--freeze-cgroup*:: *--freeze-cgroup*::
Use cgroup freezer to collect processes. Use cgroup freezer to collect processes.
*--manage-cgroups*:: *--manage-cgroups*::
Collect cgroups into the image thus they gonna be restored then. Collect cgroups into the image thus they gonna be restored then.
Without this argument *criu* will not save cgroups configuration Without this option, *criu* will not save cgroups configuration
associated with a task. associated with a task.
*--cgroup-props* '<spec>':: *--cgroup-props* 'spec'::
Specify controllers and their properties to be carried into the Specify controllers and their properties to be saved into the
image file. *criu* predefines specifications for common controllers image file. *criu* predefines specifications for common controllers,
but since the kernel can add new controllers and modify their but since the kernel can add new controllers and modify their
properties there should be a way to specify ones matched the kernel. properties, there should be a way to specify ones matched the kernel.
+ +
'<spec>' describes the controller and properties specification in 'spec' argument describes the controller and properties specification in
simplified YAML form: a simplified YAML form:
+ +
---------- ----------
"c1": "c1":
@@ -169,93 +168,95 @@ simplified YAML form:
- "properties": ["c", "d"] - "properties": ["c", "d"]
---------- ----------
+ +
Where 'c1' and 'c2' are controllers names, and 'a', 'b', 'c', 'd' are where 'c1' and 'c2' are controllers names, and 'a', 'b', 'c', 'd' are
their properties. their properties.
+ +
Mark the format: double quotes, spaces and new lines are required. Note the format: double quotes, spaces and new lines are required.
The '<strategy>' specify how to behave if controller specified already The 'strategy' specifies what to do if a controller specified already
exist as built in one: *criu* either 'merge' or 'replace' them. exists as a built-in one: *criu* can either *merge* or *replace* such.
+ +
Thus for command line argument the example above will look like: For example, the command line for the above example should look like this:
+ +
---------- ----------
--cgroup-props "\"c1\":\n - \"strategy\": \"merge\"\n - \"properties\": [\"a\", \"b\"]\n \"c2\":\n - \"strategy\": \"replace\"\n - \"properties\": [\"c\", \"d\"]" --cgroup-props "\"c1\":\n - \"strategy\": \"merge\"\n - \"properties\": [\"a\", \"b\"]\n \"c2\":\n - \"strategy\": \"replace\"\n - \"properties\": [\"c\", \"d\"]"
---------- ----------
*--cgroup-props-file* '<path>':: *--cgroup-props-file* 'file'::
Same as *--cgroup-props* except the specification is read from Same as *--cgroup-props*, except the specification is read from
a file pointed by '<path>'. the 'file'.
*--cgroup-dump-controller* '<name>':: *--cgroup-dump-controller* 'name'::
Dump controller with '<name>' only, skipping anything else Dump a controller with 'name' only, skipping anything else that was
automatically discovered (usually via procfs filesystem). Suitable discovered automatically (usually via */proc*). This option is
when need *criu* to skip some controllers. useful when one needs *criu* to skip some controllers.
*--cgroup-props-ignore-default*:: *--cgroup-props-ignore-default*::
When combined with *--cgroup-props* makes *criu* to substitute When combined with *--cgroup-props*, makes *criu* substitute
predefined controller property with new one shipped. Otherwise a predefined controller property with the new one shipped. If the option
predefined properties are merged with provided. is not used, the predefined properties are merged with the provided ones.
*--tcp-established*:: *--tcp-established*::
Checkpoint established TCP connections. Checkpoint established TCP connections.
*--skip-in-flight*:: *--skip-in-flight*::
This option skips in-flight TCP connections. If TCP connections This option skips in-flight TCP connections. If any TCP connections
are found which are not yet completely established, criu will that are not yet completely established are found, *criu* ignores
ignore these connections in favor of erroring out. these connections, rather than errors out.
The TCP stack on the client side is expected to handle the The TCP stack on the client side is expected to handle the
re-connect gracefully. re-connect gracefully.
*--veth-pair* '<IN>'*=*'<OUT>':: *--veth-pair* 'IN'*=*'OUT'::
Correspondence between outside and inside names of veth devices. Relation between outside and inside names of veth devices.
*--evasive-devices*:: *--evasive-devices*::
Use any path to a device file if the original one is inaccessible. Use any path to a device file if the original one is inaccessible.
*--page-server*:: *--page-server*::
Send pages to a page server (see *page-server* command). Send pages to a page server (see the *page-server* command).
*--force-irmap*:: *--force-irmap*::
Force resolving names for inotify and fsnotify watches. Force resolving names for inotify and fsnotify watches.
*--auto-dedup*:: *--auto-dedup*::
Deduplicate "old" data in pages images of previous *dump*. Which implies Deduplicate "old" data in pages images of previous *dump*. This option
incremental *dump* mode (see *pre-dump* command). implies incremental *dump* mode (see the *pre-dump* command).
*-l*, *--file-locks*:: *-l*, *--file-locks*::
Dump file locks. It is necessary to make sure that all file lock users Dump file locks. It is necessary to make sure that all file lock users
are taken into dump, so it is only safe to use this for enclosed containers are taken into dump, so it is only safe to use this for enclosed containers
where locks are not holed by someone outside of it. where locks are not held by any processes outside of dumped process tree.
*-M*, *--ext-mount-map* '<KEY>'*:*'<VAL>':: *-M*, *--ext-mount-map* 'KEY'*:*'VAL'::
Setup mapping for external mounts. '<KEY>' is a mountpoint inside container Setup mapping for external mounts. Here 'KEY' is a mountpoint inside
and corresponding '<VAL>' is a string that will be written into the image a container, and corresponding 'VAL' is a string to be written into
as mountpoint\'s root value. the image as the mountpoint\'s root value.
*--link-remap*:: *--link-remap*::
Allow one to link unlinked files back when possible (modifies FS till *restore*). Allows to link unlinked files back, if possible (modifies filesystem
during *restore*).
*--ghost-limit* 'size':: *--ghost-limit* 'size'::
Allow one to specify maximum allowed size of deleted file to be carried Set the maximum size of deleted file to be carried inside image.
inside image files. By default up to 1M file is allowed. It is done in By default, up to 1M file is allowed. Using this
a sake to not carry big files inside images. 'size' may be postfixed option allows to not put big deleted files inside images. Argument
with 'K', 'M' or 'G' (which stands for kilo, mega and gigabytes accordingly). 'size' may be postfixed with a *K*, *M* or *G*, which stands for kilo-,
mega, and gigabytes, accordingly.
*-j*, *--shell-job*:: *-j*, *--shell-job*::
Allow one to dump shell jobs. This implies the restored task will inherit session and Allow one to dump shell jobs. This implies the restored task will
process group ID from the criu itself. Also this option allows one to migrate a inherit session and process group ID from the *criu* itself.
single external tty connection, in other words this option allows one to migrate This option also allows to migrate a single external tty connection,
such application as "top" and friends. If passed on *dump* it must be to migrate applications like *top*. If used with *dump* command,
specified on *restore* as well. it must be specified with *restore* as well.
*--cpu-cap* [,'<cap>']:: *--cpu-cap* ['cap'[,'cap'...]]::
Specify 'cap' CPU capability to be written into an image file. Basically Specify CPU capabilities to write to an image file. The argument is a
if '<cap>' is one of *all*, *cpu* or *ins*, then *criu* writes CPU related comma-separated list of *none*, *fpu*, *cpu*, *ins*, *all*. If the
information into image file. If the option is omitted or set to *none* argument is omitted or set to *none*, capabilities will not be written,
then image will not be written. By default *criu* do not write this image. which is the default behavior.
*--cgroup-root* '[<controller>:]/<newroot>':: *--cgroup-root* ['controller':]/'newroot'::
Change the root for the controller that will be dumped. By default, CRIU Change the root for the controller that will be dumped. By default, *criu*
simply dumps everything below where any of the tasks live. However, if a simply dumps everything below where any of the tasks live. However, if a
container moves all of its tasks into a cgroup directory below the container container moves all of its tasks into a cgroup directory below the container
engine's default directory for tasks, permissions will not be preserved on engine's default directory for tasks, permissions will not be preserved on
@@ -265,42 +266,44 @@ Thus for command line argument the example above will look like:
~~~~~~~~~ ~~~~~~~~~
Restores previously checkpointed processes. Restores previously checkpointed processes.
*--inherit-fd* 'fd[<num>]:<existing>':: *--inherit-fd* *fd[*'N'*]:*'path'::
Inherit file descriptors. This allows one to treat file descriptor '<num>' as Inherit file descriptors. This asks *criu* to use an already opened
being already opened via '<existing>' one and instead of trying to open we file descriptor 'N' for restoring a file indentified by 'path'. Note
inherit it. that the 'N' must be enclosed in a literal square brackets, that
usually needs to be escaped from shell.
*-d*, *--restore-detached*:: *-d*, *--restore-detached*::
Detach *criu* itself once restore is complete. Detach *criu* itself once restore is complete.
*-S*, *--restore-sibling*:: *-S*, *--restore-sibling*::
Restore root task as a sibling (make sense with *--restore-detached*) only. Restore root task as a sibling (makes sense only with
*--restore-detached*).
*-r*, *--root* '<path>':: *-r*, *--root* 'path'::
Change the root filesystem to <path> (when run in mount namespace). Change the root filesystem to 'path' (when run in a mount namespace).
*--manage-cgroups* [<mode>]:: *--manage-cgroups* ['mode']::
Restore cgroups configuration associated with a task from the image. Restore cgroups configuration associated with a task from the image.
Controllers are always restored in optimistic way -- if already present Controllers are always restored in an optimistic way -- if already present
in system *criu* reuses it, otherwise it will be created. in system, *criu* reuses it, otherwise it will be created.
+
The '<mode>' may be one of below.
- *none*. Do not restore cgroup properties but require cgroup to The 'mode' may be one of the following:
*none*::: Do not restore cgroup properties but require cgroup to
pre-exist at the moment of *restore* procedure. pre-exist at the moment of *restore* procedure.
- *props*. Restore cgroup properties and require cgroup to pre-exist. *props*::: Restore cgroup properties and require cgroup to pre-exist.
- *soft*. Restore cgroup properties if only cgroup has been created *soft*::: Restore cgroup properties if only cgroup has been created
by *criu*, otherwise do not restore properties. This is the by *criu*, otherwise do not restore properties. This is the
default if mode is unspecified. default if mode is unspecified.
- *full*. Always restore all cgroups and their properties. *full*::: Always restore all cgroups and their properties.
- *strict*. Restore all cgroups and their properties from the scratch, *strict*::: Restore all cgroups and their properties from the scratch,
requiring them to not present in the system. requiring them to not present in the system.
*--cgroup-root* '[<controller>:]/<newroot>':: *--cgroup-root* ['controller'*:*]/'newroot'::
Change the root cgroup the controller will be installed into. No controller Change the root cgroup the controller will be installed into. No controller
means that root is the default for all controllers not specified. means that root is the default for all controllers not specified.
@@ -309,23 +312,24 @@ The '<mode>' may be one of below.
the network has been locked between *dump* and *restore* phases so other the network has been locked between *dump* and *restore* phases so other
side of a connection simply notice a kind of lag. side of a connection simply notice a kind of lag.
*--veth-pair* '<IN>'*=*'<OUT>':: *--veth-pair* 'IN'*=*'OUT'::
Correspondence between outside and inside names of veth devices. Correspondence between outside and inside names of veth devices.
*-l*, *--file-locks*:: *-l*, *--file-locks*::
Restore file locks from the image. Restore file locks from the image.
*-M*, *--ext-mount-map* '<KEY>'*:*'<VAL>':: *-M*, *--ext-mount-map* 'KEY'*:*'VAL'::
Setup mapping for external mounts. '<KEY>' is the value from the image Setup mapping for external mounts. 'KEY' is the value from the image
('<VAL>' from dump) and the '<VAL>' is the path on host that will be ('VAL' from dump) and the 'VAL' is the path on host that will be
bind-mounted into container (to the mountpoint path from image). bind-mounted into container (to the mountpoint path from image).
*--ext-mount-map* *auto*:: *--ext-mount-map* *auto*::
This is a special case. If this flag is passed, when an external This is a special case. If this flag is passed, when an external
mount is missing from the command line '*--ext-mount-map* <KEY>:<VAL>' syntax, mount is missing from the command line '*--ext-mount-map* KEY:VAL' syntax,
criu attempts to automatically resolve this mount from its namespace. criu attempts to automatically resolve this mount from its namespace.
*--enable-external-sharing*, *--enable-external-masters*:: *--enable-external-sharing*::
*--enable-external-masters*::
These flags enable external shared or slave mounts to be resolved These flags enable external shared or slave mounts to be resolved
automatically when '*--ext-mount-map auto*' is passed. automatically when '*--ext-mount-map auto*' is passed.
@@ -336,19 +340,20 @@ The '<mode>' may be one of below.
Restore shell jobs, in other words inherit session and process group Restore shell jobs, in other words inherit session and process group
ID from the criu itself. ID from the criu itself.
*--cpu-cap* ['<cap>','<cap>']:: *--cpu-cap* ['cap'[,'cap'...]]::
Specify '<cap>' CPU capability to be present on the CPU the process is Specify CPU capabilities to be present on the CPU the process is
restoring. To inverse capability prefix it with *^*. This option implies restoring. To inverse a capability, prefix it with *^*. This option implies
that *--cpu-cap* has been passed on *dump* as well, except *fpu* option that *--cpu-cap* has been passed on *dump* as well, except *fpu* option
case. case. The 'cap' argument can be the following (or a set of comma-separated
values):
- *all*. Require all capabilities. This is *default* mode if *--cpu-cap* *all*::: Require all capabilities. This is *default* mode if *--cpu-cap*
is passed without arguments. Most safe mode. is passed without arguments. Most safe mode.
- *cpu*. Require the CPU to have all capabilities in image to match *cpu*::: Require the CPU to have all capabilities in image to match
runtime CPU. runtime CPU.
- *fpu*. Require the CPU to have compatible FPU. For example the process *fpu*::: Require the CPU to have compatible FPU. For example the process
might be dumped with xsave capability but attempted to restore might be dumped with xsave capability but attempted to restore
without it present on target CPU. In such case we refuse to without it present on target CPU. In such case we refuse to
proceed. This is *default* mode if *--cpu-cap* is not present proceed. This is *default* mode if *--cpu-cap* is not present
@@ -356,52 +361,50 @@ The '<mode>' may be one of below.
on the *dump* no *--cpu-cap* have been specified because FPU on the *dump* no *--cpu-cap* have been specified because FPU
frames are always encoded into images. frames are always encoded into images.
- *ins*. Require CPU compatibility on instructions level. *ins*::: Require CPU compatibility on instructions level.
- *none*. Ignore capabilities. Most dangerous mode. The behaviour is *none*::: Ignore capabilities. Most dangerous mode. The behaviour is
implementation dependent. Try to not use it until really implementation dependent. Try to not use it until really
required. required.
+ +
One possible need of using this option is when For example, this option can be used in case *--cpu-cap=cpu* was used
*--cpu-cap*=*cpu* has been passed on *dump* then images are during *dump*, and images are migrated to a less capable CPU and are
migrated to a less capable processor and one need to *restore* to be restored. By default, *criu* shows an error that CPU capabilities
this application, by default *criu* will refuse to proceed without are not adequate, but this can be suppressed by using *--cpu-cap=none*.
relaxing capability with *--cpu-cap*=*none* parameter.
*check* *check*
~~~~~~~ ~~~~~~~
Checks whether the kernel supports the features that *criu* needs to Checks whether the kernel supports the features needed by *criu* to
successfully dump and restore a process tree. dump and restore a process tree.
There are three categories of kernel support as described below. *criu There are three categories of kernel support, as described below. *criu
check* always checks Category 1 features unless *--feature* is specified check* always checks Category 1 features unless *--feature* is specified
which only checks the specified feature. which only checks a specified feature.
- *Category 1*. Absolutely required. These are features like *Category 1*::: Absolutely required. These are features like support for
'/proc/<pid>/map_files', 'NETLINK_SOCK_DIAG' socket */proc/PID/map_files*, *NETLINK_SOCK_DIAG* socket
monitoring, '/proc/sys/kernel/ns_last_pid', etc. monitoring, */proc/sys/kernel/ns_last_pid* etc.
- *Category 2*. Required only for specific cases. These are features *Category 2*::: Required only for specific cases. These are features
like aio remap, '/dev/net/tun', etc. that are like AIO remap, */dev/net/tun* and others that are only
required if the process being dumped or restored required if a process being dumped or restored
is using them. is using those.
- *Category 3*. Experimental. These are features like task-diag that *Category 3*::: Experimental. These are features like *task-diag* that
are used for experimental purposes (mostly are used for experimental purposes (mostly
during development). during development).
If there are no errors or warnings, *criu* prints "Looks good." and its If there are no errors or warnings, *criu* prints "Looks good." and its
exit code will be 0. exit code is 0.
A missing Category 1 feature causes *criu* to print "Does not look good." A missing Category 1 feature causes *criu* to print "Does not look good."
and its exit code will be non-zero. and its exit code is non-zero.
Missing Category 2 and 3 features cause *criu* to print "Looks good but Missing Category 2 and 3 features cause *criu* to print "Looks good but
some kernel features are missing which, depending on your process tree, ..." and its exit code is be non-zero.
may cause dump or restore failure." and its exit code will be non-zero.
Without an argument, *criu check* checks Category 1 features. This Without any options, *criu check* checks Category 1 features. This
behavior can change with the following options: behavior can be changed by using the following options:
*--extra*:: *--extra*::
Check kernel support for Category 2 features. Check kernel support for Category 2 features.
@@ -412,8 +415,8 @@ behavior can change with the following options:
*--all*:: *--all*::
Check kernel support for Category 1, 2, and 3 features. Check kernel support for Category 1, 2, and 3 features.
*--feature* '<name>':: *--feature* 'name'::
Check a specific feature. If '<name>' is 'list', a list of valid Check a specific feature. If 'name' is *list*, a list of valid
kernel feature names that can be checked will be printed. kernel feature names that can be checked will be printed.
*page-server* *page-server*
@@ -423,21 +426,22 @@ Launches *criu* in page server mode.
*--daemon*:: *--daemon*::
Runs page server as a daemon (background process). Runs page server as a daemon (background process).
*--address* '<address>':: *--address* 'address'::
Page server IP address. Page server IP address.
*--port* '<number>':: *--port* 'number'::
Page server port number. Page server port number.
*exec* *exec*
~~~~~~ ~~~~~~
Executes a system call inside a destination task\'s context. Executes a system call inside a destination task\'s context. This functionality
is depreated; please use *Compel* instead.
*service* *service*
~~~~~~~~~ ~~~~~~~~~
Launches *criu* in RPC daemon mode where *criu* is listening for Launches *criu* in RPC daemon mode, where *criu* is listening for
RPC commands over socket to perform. This is convenient for the RPC commands over socket to perform. This is convenient for a
case where daemon itself is running in a privilege (superuser) mode case where daemon itself is running in a privileged (superuser) mode
but clients are not. but clients are not.
dedup dedup
@@ -446,40 +450,14 @@ Starts pagemap data deduplication procedure, where *criu* scans over all
pagemap files and tries to minimize the number of pagemap entries by pagemap files and tries to minimize the number of pagemap entries by
obtaining the references from a parent pagemap image. obtaining the references from a parent pagemap image.
*cpuinfo* *dump* cpuinfo dump
~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~
Fetches current CPU features and write them into an image file. Fetches current CPU features and write them into an image file.
*cpuinfo* *check* cpuinfo check
~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~
Fetches current CPU features (ie CPU the *criu* is running on) and test if Fetches current CPU features (i.e. CPU the *criu* is running on) and test if
they are compatible with ones present in image file. they are compatible with the ones present in an image file.
SYSCALLS EXECUTION
------------------
To run a system call in another task\'s context use
----------
criu exec -t pid syscall-string
----------
command. The 'syscall-string' should look like
----------
syscall-name syscall-arguments ...
----------
Each command line argument is transformed into the system call argument by
the following rules:
* If one starts with *&*, the rest of it gets copied to the target task\'s
address space and the respective syscall argument is the pointer to this
string;
* Otherwise it is treated as a number (converted with strtol) and is directly
passed into the system call.
EXAMPLES EXAMPLES
@@ -497,24 +475,12 @@ To restore this program detaching criu itself:
criu restore -d -D checkpoint criu restore -d -D checkpoint
---------- ----------
To close a file descriptor number *1* in task with pid *1234*:
----------
criu exec -t 1234 close 1
----------
To open a file named */foo/bar* for read-write in the task with pid *1234*:
----------
criu exec -t 1234 open '&/foo/bar' 2
----------
AUTHOR AUTHOR
------ ------
OpenVZ team. The CRIU team.
COPYRIGHT COPYRIGHT
--------- ---------
Copyright \(C) 2011-2015, Parallels Inc. Copyright \(C) 2011-2016, Parallels Holdings, Inc.