NAME

       /etc/xen/xl.conf - XL Global/Host Configuration

DESCRIPTION

       The xl.conf file allows configuration of host-wide "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

       domid_policy="xen"|"random"
           Determines how domain-id is set when creating a new domain.

           If set to "xen" then the hypervisor will allocate new domain-id values on a sequential basis.

           If set to "random" then a random domain-id value will be chosen.

           Default: "xen"

       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: value of Xen command line gnttab_max_frames parameter (or its default value if unspecified).

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

           Default: value of Xen command line gnttab_max_maptrack_frames parameter  (or  its  default  value  if
           unspecified).

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

           Default: maximum grant version supported by the hypervisor.

       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" <https://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.  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.

           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   Free memory as reported by the hypervisor is used for 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.

       bootloader_restrict=BOOLEAN
           System  wide  default  for  whether  the  bootloader  should be run in a restricted environment.  See
           xl.cfg(5) bootloader_restrict for more information on how to setup and use the option.

SEE ALSO

       xl(1)
       xl.cfg(5)
       https://www.json.org/

4.20.1-pre                                         2025-05-05                                         xl.conf(5)