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

amurleopard

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.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.

        Note that the claim call is not attempted if "superpages" option is
        used in the guest config (see xl.cfg(5)).

        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).

SEE ALSO
    xl(1)
    xl.cfg(5)
    http://www.json.org/