xl.conf(5) Xen xl.conf(5)NAME
/etc/xen/xl.conf - XL Global/Host Configuration
DESCRIPTION
The xl.conf file allows configuration of hostwide "xl" toolstack
options.
For details of per-domain configuration options please see xl.cfg(5).
SYNTAX
The config file consists of a series of "KEY=VALUE" pairs.
A value "VALUE" is one of:
"STRING"
A string, surrounded by either single or double quotes.
NUMBER
A number, in either decimal, octal (using a 0 prefix) or
hexadecimal (using an "0x" prefix).
BOOLEAN
A "NUMBER" interpreted as "False" (0) or "True" (any other value).
[ VALUE, VALUE, ... ]
A list of "VALUES" of the above types. Lists are homogeneous and
are not nested.
The semantics of each "KEY" defines which form of "VALUE" is required.
OPTIONS
autoballoon="off"|"on"|"auto"
If set to "on" then "xl" will automatically reduce the amount of
memory assigned to domain 0 in order to free memory for new
domains.
If set to "off" then "xl" will not automatically reduce the amount
of domain 0 memory.
If set to "auto" then auto-ballooning will be disabled if the
"dom0_mem" option was provided on the Xen command line.
You are strongly recommended to set this to "off" (or "auto") if
you use the "dom0_mem" hypervisor command line to reduce the amount
of memory given to domain 0 by default.
Default: "auto"
run_hotplug_scripts=BOOLEAN
If disabled hotplug scripts will be called from udev, as it used to
be in the previous releases. With the default option, hotplug
scripts will be launched by xl directly.
Default: 1
lockfile="PATH"
Sets the path to the lock file used by xl to serialise certain
operations (primarily domain creation).
Default: "/var/lock/xl"
vif.default.script="PATH"
Configures the default hotplug script used by virtual network
devices.
The old vifscript option is deprecated and should not be used.
Default: "/etc/xen/scripts/vif-bridge"
vif.default.bridge="NAME"
Configures the default bridge to set for virtual network devices.
The old defaultbridge option is deprecated and should not be used.
Default: "xenbr0"
vif.default.gatewaydev="NAME"
Configures the default gateway device to set for virtual network
devices.
Default: "None"
output_format="json|sxp"
Configures the default output format used by xl when printing
"machine readable" information. The default is to use the "JSON"
<http://www.json.org/> syntax. However for compatibility with the
previous "xm" toolstack this can be configured to use the old "SXP"
(S-Expression-like) syntax instead.
Default: "json"
blkdev_start="NAME"
Configures the name of the first block device to be used for
temporary block device allocations by the toolstack. The default
choice is "xvda".
claim_mode=BOOLEAN
If this option is enabled then when a guest is created there will
be an guarantee that there is memory available for the guest. This
is an particularly acute problem on hosts with memory over-
provisioned guests that use tmem and have self-balloon enabled
(which is the default option). The self-balloon mechanism can
deflate/inflate the balloon quickly and the amount of free memory
(which "xl info" can show) is stale the moment it is printed. When
claim is enabled a reservation for the amount of memory (see
'memory' in xl.conf(5)) is set, which is then reduced as the
domain's memory is populated and eventually reaches zero. The free
memory in "xl info" is the combination of the hypervisor's free
heap memory minus the outstanding claims value.
If the reservation cannot be meet the guest creation fails
immediately instead of taking seconds/minutes (depending on the
size of the guest) while the guest is populated.
Note that to enable tmem type guests, one needs to provide "tmem"
on the Xen hypervisor argument and as well on the Linux kernel
command line.
Note that the claim call is not attempted if "superpages" option is
used in the guest config (see xl.cfg(5)).
Default: 0
0 No claim is made. Memory population during guest creation will
be attempted as normal and may fail due to memory exhaustion.
1 Normal memory and freeable pool of ephemeral pages (tmem) is
used when calculating whether there is enough memory free to
launch a guest. This guarantees immediate feedback whether the
guest can be launched due to memory exhaustion (which can take
a long time to find out if launching massively huge guests).
SEE ALSOxl(1)xl.cfg(5)
http://www.json.org/
4.3.0_14-1.3 2013-07-09 xl.conf(5)
