Ubuntu Manpage: /etc/xen/xl.conf - XL Global/Host Configuration

Provided by: xen-utils-common_4.11.3+24-g14b62ab3e5-1ubuntu2.3_amd64

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"

max_grant_frames=NUMBER
Sets the default value for the "max_grant_frames" domain config value.

Default: 32 on hosts up to 16TB of memory, 64 on hosts larger than 16TB

max_maptrack_frames=NUMBER
Sets the default value for the "max_maptrack_frames" domain config value.

Default: 1024

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.backend="NAME"
Configures the default backend to set for virtual network devices.

Default: 0

vif.default.gatewaydev="NAME"
Configures the default gateway device to set for virtual network devices.

Default: "None"

remus.default.netbufscript="PATH"
Configures the default script used by Remus to setup network buffering.

Default: "/etc/xen/scripts/remus-netbuf-setup"

colo.default.proxyscript="PATH"
Configures the default script used by COLO to setup colo-proxy.

Default: "/etc/xen/scripts/colo-proxy-setup"

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.

Default: 1

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).

vm.cpumask="CPULIST"
vm.hvm.cpumask="CPULIST"
vm.pv.cpumask="CPULIST"
Global masks that are applied when creating guests and pinning vcpus to indicate which cpus they are
allowed to run on. Specifically, "vm.cpumask" applies to all guest types, "vm.hvm.cpumask" applies
to both HVM and PVH guests and "vm.pv.cpumask" applies to PV guests.

The hard affinity of guest's vcpus are logical-AND'ed with respective masks. If the resulting
affinity mask is empty, operation will fail.

Use --ignore-global-affinity-masks to skip applying global masks.

The default value for these masks are all 1's, i.e. all cpus are allowed.

Due to bug(s), these options may not interact well with other options concerning CPU affinity. One
example is CPU pools. Users should always double check that the required affinity has taken effect.

NAME

DESCRIPTION

SYNTAX

OPTIONS

SEE ALSO