xl.cfg(5) Xen xl.cfg(5)NAMExl.cfg - XL Domain Configuration File Syntax
SYNOPSIS
/etc/xen/xldomain
DESCRIPTION
To create a VM (a domain in Xen terminology, sometimes called a guest)
with xl requires the provision of a domain config file. Typically
these live in `/etc/xen/DOMAIN.cfg` where DOMAIN is the name of the
domain.
SYNTAX
A domain config file consists of a series of "KEY=VALUE" pairs.
Some "KEY"s are mandatory, others are general options which apply to
any guest type while others relate only to specific guest types (e.g.
PV or HVM guests).
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
Mandatory Configuration Items
The following key is mandatory for any guest type:
name="NAME"
Specifies the name of the domain. Names of domains existing on a
single host must be unique.
Selecting Guest Type
builder="generic"
Specifies that this is to be a PV domain. This is the default.
builder="hvm"
Specifies that this is to be an HVM domain. That is, a fully
virtualised computer with emulated BIOS, disk and network
peripherals, etc. The default is a PV domain, suitable for hosting
Xen-aware guest operating systems.
General Options
The following options apply to guests of any type.
CPU Allocation
pool="CPUPOOLNAME"
Put the guest's vcpus into the named cpu pool.
vcpus=N
Start the guest with N vcpus initially online.
maxvcpus=M
Allow the guest to bring up a maximum of M vcpus. At start of day
if `vcpus=N` is less than `maxvcpus=M` then the first `N` vcpus
will be created online and the remainder will be offline.
cpus="CPU-LIST"
List of which cpus the guest is allowed to use. By default xl will
pick some cpus on its own (see below). A "CPU-LIST" may be
specified as follows:
"all"
To allow all the vcpus of the guest to run on all the cpus on
the host.
"0-3,5,^1"
To allow all the vcpus of the guest to run on cpus 0,2,3,5.
["2", "3"] (or [2, 3])
To ask for specific vcpu mapping. That means (in this example),
vcpu #0 of the guest will run on cpu #2 of the host and vcpu #1
of the guest will run on cpu #3 of the host.
If this option is not specified, libxl automatically tries to place
the new domain on the host's NUMA nodes (provided the host has more
than one NUMA node) by pinning it to the cpus of those nodes. A
heuristic approach is utilized with the goals of maximizing
performance for the domain and, at the same time, achieving
efficient utilization of the host's CPUs and RAM.
CPU Scheduling
cpu_weight=WEIGHT
A domain with a weight of 512 will get twice as much CPU as a
domain with a weight of 256 on a contended host. Legal weights
range from 1 to 65535 and the default is 256. Honoured by the
credit, credit2 and sedf schedulers.
cap=N
The cap optionally fixes the maximum amount of CPU a domain will be
able to consume, even if the host system has idle CPU cycles. The
cap is expressed in percentage of one physical CPU: 100 is 1
physical CPU, 50 is half a CPU, 400 is 4 CPUs, etc. The default,
0, means there is no upper cap. Honoured by the credit and credit2
schedulers.
NB: Many systems have features that will scale down the computing
power of a cpu that is not 100% utilized. This can be in the
operating system, but can also sometimes be below the operating
system in the BIOS. If you set a cap such that individual cores
are running at less than 100%, this may have an impact on the
performance of your workload over and above the impact of the cap.
For example, if your processor runs at 2GHz, and you cap a vm at
50%, the power management system may also reduce the clock speed to
1GHz; the effect will be that your VM gets 25% of the available
power (50% of 1GHz) rather than 50% (50% of 2GHz). If you are not
getting the performance you expect, look at performance and cpufreq
options in your operating system and your BIOS.
period=NANOSECONDS
The normal EDF scheduling usage in nanoseconds. This means every
period the domain gets cpu time defined in slice. Honoured by the
sedf scheduler.
slice=NANOSECONDS
The normal EDF scheduling usage in nanoseconds. it defines the time
a domain get every period time. Honoured by the sedf scheduler.
latency=N
Scaled period if domain is doing heavy I/O. Honoured by the sedf
scheduler.
extratime=BOOLEAN
Flag for allowing domain to run in extra time. Honoured by the
sedf scheduler.
Memory Allocation
memory=MBYTES
Start the guest with MBYTES megabytes of RAM.
maxmem=MBYTES
Specifies the maximum amount of memory a guest can ever see. The
value of maxmem= must be equal or greater than memory=.
In combination with memory= it will start the guest "pre-
ballooned", if the values of memory= and maxmem= differ. A "pre-
ballooned" HVM guest needs a balloon driver, without a balloon
driver it will crash.
Event Actions
on_poweroff="ACTION"
Specifies what should be done with the domain if it shuts itself
down. The "ACTION"s are:
destroy
destroy the domain
restart
destroy the domain and immediately create a new domain with the
same configuration
rename-restart
rename the domain which terminated, and then immediately create
a new domain with the same configuration as the original
preserve
keep the domain. It can be examined, and later destroyed with
`xl destroy`.
coredump-destroy
write a "coredump" of the domain to /var/xen/dump/NAME and then
destroy the domain.
coredump-restart
write a "coredump" of the domain to /var/xen/dump/NAME and then
restart the domain.
The default for "on_poweroff" is "destroy".
on_reboot="ACTION"
Action to take if the domain shuts down with a reason code
requesting a reboot. Default is "restart".
on_watchdog="ACTION"
Action to take if the domain shuts down due to a Xen watchdog
timeout. Default is "destroy".
on_crash="ACTION"
Action to take if the domain crashes. Default is "destroy".
Other Options
uuid="UUID"
Specifies the UUID of the domain. If not specified, a fresh unique
UUID will be generated.
seclabel="LABEL"
Assign an XSM security label to this domain.
init_seclabel="LABEL"
Specify an XSM security label used for this domain temporarily
during its build. The domain's XSM label will be changed to the
execution seclabel (specified by "seclabel") once the build is
complete, prior to unpausing the domain. With a properly
constructed security policy (such as nomigrate_t in the example
policy), this can be used to build a domain whose memory is not
accessible to the toolstack domain.
nomigrate=BOOLEAN
Disable migration of this domain. This enables certain other
features which are incompatible with migration. Currently this is
limited to enabling the invariant TSC feature flag in cpuid results
when TSC is not emulated.
Devices
The following options define the paravirtual, emulated and physical
devices which the guest will contain.
disk=[ "DISK_SPEC_STRING", "DISK_SPEC_STRING", ...]
Specifies the disks (both emulated disks and Xen virtual block
devices) which are to be provided to the guest, and what objects on
the they should map to. See docs/misc/xl-disk-configuration.txt.
vif=[ "NET_SPEC_STRING", "NET_SPEC_STRING", ...]
Specifies the networking provision (both emulated network adapters,
and Xen virtual interfaces) to provided to the guest. See
docs/misc/xl-network-configuration.markdown.
vtpm=[ "VTPM_SPEC_STRING", "VTPM_SPEC_STRING", ...]
Specifies the virtual trusted platform module to be provided to the
guest. Please see docs/misc/vtpm.txt for more details.
Each VTPM_SPEC_STRING is a comma-separated list of "KEY=VALUE"
settings, from the following list:
"backend=DOMAIN"
Specify the backend domain name of id. This value is required!
If this domain is a guest, the backend should be set to the
vtpm domain name. If this domain is a vtpm, the backend should
be set to the vtpm manager domain name.
"uuid=UUID"
Specify the uuid of this vtpm device. The uuid is used to
uniquely identify the vtpm device. You can create one using the
uuidgen program on unix systems. If left unspecified, a new
uuid will be randomly generated every time the domain boots.
If this is a vtpm domain, you should specify a value. The value
is optional if this is a guest domain.
vfb=[ "VFB_SPEC_STRING", "VFB_SPEC_STRING", ...]
Specifies the paravirtual framebuffer devices which should be
supplied to the domain.
This options does not control the emulated graphics card presented
to an HVM guest. See "Emulated VGA Graphics Device" below for how
to configure the emulated device.
Each VFB_SPEC_STRING is a comma-separated list of "KEY=VALUE"
settings, from the following list:
"vnc=BOOLEAN"
Allow access to the display via the VNC protocol. This enables
the other VNC-related settings. The default is to enable this.
"vnclisten="ADDRESS[:DISPLAYNUM]""
Specifies the IP address, and optionally VNC display number, to
use.
NB that if you specify the display number here, you should not
use vncdisplay.
"vncdisplay=DISPLAYNUM"
Specifies the VNC display number to use. The actual TCP port
number will be DISPLAYNUM+5900.
NB that you should not use this option if you set the
displaynum in the vnclisten string.
"vncunused=BOOLEAN"
Requests that the VNC display setup search for a free TCP port
to use. The actual display used can be accessed with "xl
vncviewer".
"vncpasswd="PASSWORD""
Specifies the password for the VNC server.
"sdl=BOOLEAN"
Specifies that the display should be presented via an X window
(using Simple DirectMedia Layer). The default is to not enable
this mode.
"display=DISPLAY"
Specifies the X Window display that should be used when the sdl
option is used. Note: passing this value to the device-model is
not currently implemented, so providing this option will have
no effect.
"xauthority=XAUTHORITY"
Specifies the path to the X authority file that should be used
to connect to the X server when the sdl option is used. Note:
passing this value to the device-model is not currently
implemented, so providing this option will have no effect.
"opengl=BOOLEAN"
Enable OpenGL acceleration of the SDL display. Only effects
machines using "device_model_version="qemu-xen-traditional""
and only if the device-model was compiled with OpenGL support.
Disabled by default.
"keymap="LANG""
Configure the keymap to use for the keyboard associated with
this display. If the input method does not easily support raw
keycodes (e.g. this is often the case when using VNC) then this
allows us to correctly map the input keys into keycodes seen by
the guest. The specific values which are accepted are defined
by the version of the device-model which you are using. See
"Keymaps" below or consult the qemu(1) manpage. The default is
en-us.
pci=[ "PCI_SPEC_STRING", "PCI_SPEC_STRING", ... ]
Specifies the host PCI devices to passthrough to this guest. Each
PCI_SPEC_STRING has the form
"[DDDD:]BB:DD.F[@VSLOT],KEY=VALUE,KEY=VALUE,..." where:
DDDD:BB:DD.F
Identifies the PCI device from the host perspective in domain
(DDDD), Bus (BB), Device (DD) and Function (F) syntax. This is
the same scheme as used in the output of "lspci" for the device
in question. Note: By default "lspci" will omit the domain
(DDDD) if it is zero and it is optional here also. You may
specify the function (F) as * to indicate all functions.
@VSLOT
Specifies the virtual device where the guest will see this
device. This is equivalent to the DD which the guest sees. In a
guest DDDD and BB are "0000:00".
KEY=VALUE
Possible KEYs are:
permissive=BOOLEAN
(PV only) By default pciback only allows PV guests to write
"known safe" values into PCI config space. But many
devices require writes to other areas of config space in
order to operate properly. This tells the pciback driver
to allow all writes to PCI config space of this device by
this domain. This option should be enabled with caution:
it gives the guest much more control over the device, which
may have security or stability implications. It is
recommended to enable this option only for trusted VMs
under administrator control.
msitranslate=BOOLEAN
Specifies that MSI-INTx translation should be turned on for
the PCI device. When enabled, MSI-INTx translation will
always enable MSI on the PCI device regardless whether the
guest uses INTx or MSI. Some device drivers, such as
NVIDIA's, detect an inconsistency and do not function when
this option is enabled. Therefore the default is false (0).
power_mgmt=BOOLEAN
(HVM only) Specifies that the VM should be able to program
the D0-D3hot power management states for the PCI device.
False (0) by default.
pci_permissive=BOOLEAN
(PV only) Changes the default value of 'permissive' for all PCI
devices passed through to this VM. See permissive above.
pci_msitranslate=BOOLEAN
Changes the default value of 'msitranslate' for all PCI devices
passed through to this VM. See msitranslate above.
pci_power_mgmt=BOOLEAN
(HVM only) Changes the default value of 'power_mgmt' for all PCI
devices passed through to this VM. See power_mgt above.
gfx_passthru=BOOLEAN
Enable graphics device PCI passthrough. This option makes an
assigned PCI graphics card become primary graphics card in the VM.
The QEMU emulated graphics adapter is disabled and the VNC console
for the VM will not have any graphics output. All graphics output,
including boot time QEMU BIOS messages from the VM, will go to the
physical outputs of the passedthrough physical graphics card.
The graphics card PCI device to passthrough is chosen with pci
option, exactly in the same way as normal Xen PCI device
passthrough/assignment is done. Note that gfx_passthru does not do
any kind of sharing of the GPU, so you can only assign the GPU to
one single VM at a time.
gfx_passthru also enables various legacy VGA memory ranges, BARs,
MMIOs, and ioports to be passed thru to the VM, since those are
required for correct operation of things like VGA BIOS, text mode,
VBE, etc.
Enabling gfx_passthru option also copies the physical graphics card
video BIOS to the guest memory, and executes the VBIOS in the guest
to initialize the graphics card.
Most graphics adapters require vendor specific tweaks for properly
working graphics passthrough. See the
XenVGAPassthroughTestedAdapters
<http://wiki.xen.org/wiki/XenVGAPassthroughTestedAdapters> wiki
page for currently supported graphics cards for gfx_passthru.
gfx_passthru is currently only supported with the qemu-xen-
traditional device-model. Upstream qemu-xen device-model currently
does not have support for gfx_passthru.
Note that some graphics adapters (AMD/ATI cards, for example) do
not necessarily require gfx_passthru option, so you can use the
normal Xen PCI passthrough to assign the graphics card as a
secondary graphics card to the VM. The QEMU-emulated graphics card
remains the primary graphics card, and VNC output is available from
the QEMU-emulated primary adapter.
More information about Xen gfx_passthru feature is available on the
XenVGAPassthrough <http://wiki.xen.org/wiki/XenVGAPassthrough> wiki
page.
ioports=[ "IOPORT_RANGE", "IOPORT_RANGE", ... ]
Allow guest to access specific legacy I/O ports. Each IOPORT_RANGE
is given in hexadecimal and may either a span e.g. "2f8-2ff"
(inclusive) or a single I/O port "2f8".
It is recommended to use this option only for trusted VMs under
administrator control.
iomem=[ "IOMEM_START,NUM_PAGES", "IOMEM_START,NUM_PAGES", ... ]
Allow guest to access specific hardware I/O memory pages.
IOMEM_START is a physical page number. NUM_PAGES is the number of
pages beginning with START_PAGE to allow access. Both values must
be given in hexadecimal.
It is recommended to use this option only for trusted VMs under
administrator control.
irqs=[ NUMBER, NUMBER, ... ]
Allow a guest to access specific physical IRQs.
It is recommended to use this option only for trusted VMs under
administrator control.
Paravirtualised (PV) Guest Specific Options
The following options apply only to Paravirtual guests.
kernel="PATHNAME"
Load the specified file as the kernel image. Either kernel or
bootloader must be specified for PV guests.
ramdisk="PATHNAME"
Load the specified file as the ramdisk.
bootloader="PROGRAM"
Run "PROGRAM" to find the kernel image and ramdisk to use.
Normally "PROGRAM" would be "pygrub", which is an emulation of
grub/grub2/syslinux.
bootloader_args=[ "ARG", "ARG", ...]
Append ARGs to the arguments to the bootloader program.
Alternatively if the argument is a simple string then it will be
split into words at whitespace (this second option is deprecated).
root="STRING"
Append root="STRING" to the kernel command line (Note: it is guest
specific what meaning this has).
extra="STRING"
Append STRING to the kernel command line. Note: it is guest
specific what meaning this has).
e820_host=BOOLEAN
Selects whether to expose the host e820 (memory map) to the guest
via the virtual e820. When this option is false (0) the guest
pseudo-physical address space consists of a single contiguous RAM
region. When this option is specified the virtual e820 instead
reflects the host e820 and contains the same PCI holes. The total
amount of RAM represented by the memory map is always the same,
this option configures only how it is laid out.
Exposing the host e820 to the guest gives the guest kernel the
opportunity to set aside the required part of its pseudo-physical
address space in order to provide address space to map
passedthrough PCI devices. It is guest Operating System dependent
whether this option is required, specifically it is required when
using a mainline Linux ("pvops") kernel. This option defaults to
true (1) if any PCI passthrough devices are configured and false
(0) otherwise. If you do not configure any passthrough devices at
domain creation time but expect to hotplug devices later then you
should set this option. Conversely if your particular guest kernel
does not require this behaviour then it is safe to allow this to be
enabled but you may wish to disable it anyway.
Fully-virtualised (HVM) Guest Specific Options
The following options apply only to HVM guests.
Boot Device
boot=[c|d|n]
Selects the emulated virtual device to boot from. Options are hard
disk (c), cd-rom (d) or network/PXE (n). Multiple options can be
given and will be attempted in the order they are given. e.g. to
boot from cd-rom but fallback to the hard disk you can give dc. The
default is cd.
Paging
The following options control the mechanisms used to virtualise guest
memory. The defaults are selected to give the best results for the
common case and so you should normally leave these options unspecified.
hap=BOOLEAN
Turns "hardware assisted paging" (the use of the hardware nested
page table feature) on or off. This feature is called EPT
(Extended Page Tables) by Intel and NPT (Nested Page Tables) or RVI
(Rapid Virtualisation Indexing) by AMD. Affects HVM guests only.
If turned off, Xen will run the guest in "shadow page table" mode
where the guest's page table updates and/or TLB flushes etc. will
be emulated. Use of HAP is the default when available.
oos=BOOLEAN
Turns "out of sync pagetables" on or off. When running in shadow
page table mode, the guest's page table updates may be deferred as
specified in the Intel/AMD architecture manuals. However this may
expose unexpected bugs in the guest, or find bugs in Xen, so it is
possible to disable this feature. Use of out of sync page tables,
when Xen thinks it appropriate, is the default.
shadow_memory=MBYTES
Number of megabytes to set aside for shadowing guest pagetable
pages (effectively acting as a cache of translated pages) or to use
for HAP state. By default this is 1MB per guest vcpu plus 8KB per
MB of guest RAM. You should not normally need to adjust this value.
However if you are not using hardware assisted paging (i.e. you are
using shadow mode) and your guest workload consists of a a very
large number of similar processes then increasing this value may
improve performance.
Processor and Platform Features
The following options allow various processor and platform level
features to be hidden or exposed from the guest's point of view. This
can be useful when running older guest Operating Systems which may
misbehave when faced with more modern features. In general you should
accept the defaults for these options wherever possible.
bios="STRING"
Select the virtual firmware that is exposed to the guest. By
default, a guess is made based on the device model, but sometimes
it may be useful to request a different one, like UEFI.
rombios
Loads ROMBIOS, a 16-bit x86 compatible BIOS. This is used by
default when device_model_version=qemu-xen-traditional. This is
the only BIOS option supported when
device_model_version=qemu-xen-traditional. This is the BIOS
used by all previous Xen versions.
seabios
Loads SeaBIOS, a 16-bit x86 compatible BIOS. This is used by
default with device_model_version=qemu-xen.
ovmf
Loads OVMF, a standard UEFI firmware by Tianocore project.
Requires device_model_version=qemu-xen.
pae=BOOLEAN
Hide or expose the IA32 Physical Address Extensions. These
extensions make it possible for a 32 bit guest Operating System to
access more than 4GB of RAM. Enabling PAE also enabled other
features such as NX. PAE is required if you wish to run a 64-bit
guest Operating System. In general you should leave this enabled
and allow the guest Operating System to choose whether or not to
use PAE. (X86 only)
acpi=BOOLEAN
Expose ACPI (Advanced Configuration and Power Interface) tables
from the virtual firmware to the guest Operating System. ACPI is
required by most modern guest Operating Systems. This option is
enabled by default and usually you should omit it. However it may
be necessary to disable ACPI for compatibility with some guest
Operating Systems.
acpi_s3=BOOLEAN
Include the S3 (suspend-to-ram) power state in the virtual firmware
ACPI table. True (1) by default.
acpi_s4=BOOLEAN
Include S4 (suspend-to-disk) power state in the virtual firmware
ACPI table. True (1) by default.
apic=BOOLEAN
Include information regarding APIC (Advanced Programmable Interrupt
Controller) in the firmware/BIOS tables on a single processor
guest. This causes the MP (multiprocessor) and PIR (PCI Interrupt
Routing) tables to be exported by the virtual firmware. This option
has no effect on a guest with multiple virtual CPUS as they must
always include these tables. This option is enabled by default and
you should usually omit it but it may be necessary to disable these
firmware tables when using certain older guest Operating Systems.
These tables have been superseded by newer constructs within the
ACPI tables. (X86 only)
nx=BOOLEAN
Hides or exposes the No-eXecute capability. This allows a guest
Operating system to map pages such that they cannot be executed
which can enhance security. This options requires that PAE also be
enabled. (X86 only)
hpet=BOOLEAN
Enables or disables HPET (High Precision Event Timer). This option
is enabled by default and you should usually omit it. It may be
necessary to disable the HPET in order to improve compatibility
with guest Operating Systems (X86 only)
nestedhvm=BOOLEAN
Enable or disables guest access to hardware virtualisation
features, e.g. it allows a guest Operating System to also function
as a hypervisor. This option is disabled by default. You may want
this option if you want to run another hypervisor (including
another copy of Xen) within a Xen guest or to support a guest
Operating System which uses hardware virtualisation extensions
(e.g. Windows XP compatibility mode on more modern Windows OS).
cpuid="LIBXL_STRING" or cpuid=[ "XEND_STRING", "XEND_STRING" ]
Configure the value returned when a guest executes CPUID
instruction. Two versions of config syntax are recognized: libxl
and xend.
The libxl syntax is a comma separated list of key=value pairs,
preceded by the word "host". A few keys take a numerical value, all
others take a single character which describes what to do with the
feature bit.
Possible values for a single feature bit:
'1' -> force the corresponding bit to 1
'0' -> force to 0
'x' -> Get a safe value (pass through and mask with the default
policy)
'k' -> pass through the host bit value
's' -> as 'k' but preserve across save/restore and migration (not
implemented)
List of keys taking a value: apicidsize brandid clflush family
localapicid maxleaf model nc proccount procpkg stepping
List of keys taking a character: 3dnow 3dnowext 3dnowprefetch abm
acpi aes altmovcr8 apic avx clfsh cmov cmplegacy cmpxchg16 cmpxchg8
cntxid dca de ds dscpl dtes64 est extapic f16c ffxsr fma4 fpu fxsr
htt hypervisor ia64 ibs lahfsahf lm lwp mca mce misalignsse mmx
mmxext monitor movbe msr mtrr nodeid nx osvw osxsave pae page1gb
pat pbe pclmulqdq pdcm pge popcnt pse pse36 psn rdtscp skinit smx
ss sse sse2 sse3 sse4_1 sse4_2 sse4a ssse3 svm svm_decode svm_lbrv
svm_npt svm_nrips svm_pausefilt svm_tscrate svm_vmcbclean syscall
sysenter tbm tm tm2 topoext tsc vme vmx wdt x2apic xop xsave xtpr
The xend syntax is a list of values in the form of
'leafnum:register=bitstring,register=bitstring'
"leafnum" is the requested function,
"register" is the response register to modify
"bitstring" represents all bits in the register, its length must
be 32 chars.
Each successive character represent a lesser-significant bit,
possible values
are listed above in the libxl section.
Example to hide two features from the guest: 'tm', which is bit #29
in EDX, and 'pni' (SSE3), which is bit #0 in ECX:
xend: [
'1:ecx=xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx0,edx=xx0xxxxxxxxxxxxxxxxxxxxxxxxxxxxx'
]
libxl: 'host,tm=0,sse3=0'
More info about the CPUID instruction can be found in the processor
manuals, and in Wikipedia: <http://en.wikipedia.org/wiki/CPUID>
acpi_firmware="STRING"
Specify a path to a file that contains extra ACPI firmware tables
to pass in to a guest. The file can contain several tables in their
binary AML form concatenated together. Each table self describes
its length so no additional information is needed. These tables
will be added to the ACPI table set in the guest. Note that
existing tables cannot be overridden by this feature. For example
this cannot be used to override tables like DSDT, FADT, etc.
smbios_firmware="STRING"
Specify a path to a file that contains extra SMBIOS firmware
structures to pass in to a guest. The file can contain a set DMTF
predefined structures which will override the internal defaults.
Not all predefined structures can be overridden, only the following
types: 0, 1, 2, 3, 11, 22, 39. The file can also contain any number
of vendor defined SMBIOS structures (type 128 - 255). Since SMBIOS
structures do not present their overall size, each entry in the
file must be preceded by a 32b integer indicating the size of the
next structure.
Guest Virtual Time Controls
tsc_mode="MODE"
Specifies how the TSC (Time Stamp Counter) should be provided to
the guest (X86 only). Specifying this option as a number is
deprecated. Options are:
"default"
Guest rdtsc/p executed natively when monotonicity can be
guaranteed and emulated otherwise (with frequency scaled if
necessary).
"always_emulate"
Guest rdtsc/p always emulated at 1GHz (kernel and user). Guest
rdtsc/p always emulated and the virtual TSC will appear to
increment (kernel and user) at a fixed 1GHz rate, regardless of
the PCPU HZ rate or power state; Although there is an overhead
associated with emulation this will NOT affect underlying CPU
performance.
"native"
Guest rdtsc always executed natively (no monotonicity/frequency
guarantees); guest rdtscp emulated at native frequency if
unsupported by h/w, else executed natively.
"native_paravirt"
Same as native, except xen manages TSC_AUX register so guest
can determine when a restore/migration has occurred and assumes
guest obtains/uses pvclock-like mechanism to adjust for
monotonicity and frequency changes.
Please see docs/misc/tscmode.txt for more information on this
option.
localtime=BOOLEAN
Set the real time clock to local time or to UTC. False (0) by
default, i.e. set to UTC.
rtc_timeoffset=SECONDS
Set the real time clock offset in seconds. False (0) by default.
vpt_align=BOOLEAN
Specifies that periodic Virtual Platform Timers should be aligned
to reduce guest interrupts. Enabling this option can reduce power
consumption, especially when a guest uses a high timer interrupt
frequency (HZ) values. The default is true (1).
timer_mode=MODE
Specifies the mode for Virtual Timers. The valid values are as
follows:
"delay_for_missed_ticks"
Delay for missed ticks. Do not advance a vcpu's time beyond the
correct delivery time for interrupts that have been missed due
to preemption. Deliver missed interrupts when the vcpu is
rescheduled and advance the vcpu's virtual time stepwise for
each one.
"no_delay_for_missed_ticks"
No delay for missed ticks. As above, missed interrupts are
delivered, but guest time always tracks wallclock (i.e., real)
time while doing so.
"no_missed_ticks_pending"
No missed interrupts are held pending. Instead, to ensure ticks
are delivered at some non-zero rate, if we detect missed ticks
then the internal tick alarm is not disabled if the VCPU is
preempted during the next tick period.
"one_missed_tick_pending"
One missed tick pending. Missed interrupts are collapsed
together and delivered as one 'late tick'. Guest time always
tracks wallclock (i.e., real) time.
Support for Paravirtualisation of HVM Guests
The following options allow Paravirtualised features (such as devices)
to be exposed to the guest Operating System in an HVM guest. Utilising
these features requires specific guest support but when available they
will result in improved performance.
xen_platform_pci=BOOLEAN
Enable or disable the Xen platform PCI device. The presence of
this virtual device enables a guest Operating System (subject to
the availability of suitable drivers) to make use of
paravirtualisation features such as disk and network devices etc.
Enabling these drivers improves performance and is strongly
recommended when available. PV drivers are available for various
Operating Systems including HVM Linux
<http://wiki.xen.org/wiki/XenLinuxPVonHVMdrivers> and Microsoft
Windows <http://wiki.xen.org/wiki/XenWindowsGplPv>.
viridian=BOOLEAN
Turns on or off the exposure of MicroSoft Hyper-V (AKA viridian)
compatible enlightenments to the guest. These can improve
performance of Microsoft Windows guests from Windows Vista and
Windows 2008 onwards and setting this option for such guests is
strongly recommended. This option should be harmless for other
versions of Windows (although it will not give any benefit) and the
majority of other non-Windows OSes. However it is known to be
incompatible with some other Operating Systems and in some
circumstance can prevent Xen's own paravirtualisation interfaces
for HVM guests from being used.
Emulated VGA Graphics Device
The following options control the features of the emulated graphics
device. Many of these options behave similarly to the equivalent key
in the VFB_SPEC_STRING for configuring virtual frame buffer devices
(see above).
videoram=MBYTES
Sets the amount of RAM which the emulated video card will contain,
which in turn limits the resolutions and bit depths which will be
available. The default amount of video ram for stdvga is 8MB which
is sufficient for e.g. 1600x1200 at 32bpp and videoram option is
currently working only when using the qemu-xen-traditional device-
model.
When using the emulated Cirrus graphics card (vga="cirrus") the
amount of video ram is fixed at 4MB which is sufficient for
1024x768 at 32 bpp and videoram option is currently working only
when using the upstream qemu-xen device-model.
stdvga=BOOLEAN
Select a standard VGA card with VBE (VESA BIOS Extensions) as the
emulated graphics device. The default is false (0) which means to
emulate a Cirrus Logic GD5446 VGA card. If your guest supports VBE
2.0 or later (e.g. Windows XP onwards) then you should enable this.
stdvga supports more video ram and bigger resolutions than Cirrus.
This option is deprecated, use vga="stdvga" instead.
vga="STRING"
Selects the emulated video card (stdvga|cirrus). The default is
cirrus.
vnc=BOOLEAN
Allow access to the display via the VNC protocol. This enables the
other VNC-related settings. The default is to enable this.
vncviewer=BOOLEAN
Automatically spawn a vncviewer when creating/restoring a guest.
vnclisten="ADDRESS[:DISPLAYNUM]"
Specifies the IP address, and optionally VNC display number, to
use.
vncdisplay=DISPLAYNUM
Specifies the VNC display number to use. The actual TCP port number
will be DISPLAYNUM+5900.
vncunused=BOOLEAN
Requests that the VNC display setup search for a free TCP port to
use. The actual display used can be accessed with "xl vncviewer".
vncpasswd="PASSWORD"
Specifies the password for the VNC server.
keymap="LANG"
Configure the keymap to use for the keyboard associated with this
display. If the input method does not easily support raw keycodes
(e.g. this is often the case when using VNC) then this allows us to
correctly map the input keys into keycodes seen by the guest. The
specific values which are accepted are defined by the version of
the device-model which you are using. See "Keymaps" below or
consult the qemu(1) manpage. The default is en-us.
sdl=BOOLEAN
Specifies that the display should be presented via an X window
(using Simple DirectMedia Layer). The default is not to enable this
mode.
opengl=BOOLEAN
Enable OpenGL acceleration of the SDL display. Only effects
machines using device_model_version="qemu-xen-traditional" and only
if the device-model was compiled with OpenGL support. False (0) by
default.
nographic=BOOLEAN
Enable or disable the virtual graphics device. The default is to
provide a VGA graphics device but this option can be used to
disable it.
Spice Graphics Support
The following options control the features of SPICE.
spice=BOOLEAN
Allow access to the display via the SPICE protocol. This enables
the other SPICE-related settings.
spicehost="ADDRESS"
Specify the interface address to listen on if given, otherwise any
interface.
spiceport=NUMBER
Specify the port to listen on by the SPICE server if the SPICE is
enabled.
spicetls_port=NUMBER
Specify the secure port to listen on by the SPICE server if the
SPICE is enabled. At least one of the spiceport or spicetls_port
must be given if SPICE is enabled. NB. the options depending on
spicetls_port have not been supported.
spicedisable_ticketing=BOOLEAN
Enable client connection without password. When disabled,
spicepasswd must be set. The default is false (0).
spicepasswd="PASSWORD"
Specify the ticket password which is used by a client for
connection.
spiceagent_mouse=BOOLEAN
Whether SPICE agent is used for client mouse mode. The default is
true (1) (turn on)
Miscellaneous Emulated Hardware
serial=DEVICE
Redirect the virtual serial port to DEVICE. Please see the -serial
option in the qemu(1) manpage for details of the valid DEVICE
options. Default is vc when in graphical mode and stdio if
nographics=1 is used.
soundhw=DEVICE
Select the virtual sound card to expose to the guest. The valid
devices are defined by the device model configuration, please see
the qemu(1) manpage for details. The default is not to export any
sound device.
usb=BOOLEAN
Enables or disables an emulated USB bus in the guest.
usbdevice=[ "DEVICE", "DEVICE", ...]
Adds DEVICEs to the emulated USB bus. The USB bus must also be
enabled using usb=1. The most common use for this option is
usbdevice=['tablet'] which adds pointer device using absolute
coordinates. Such devices function better than relative coordinate
devices (such as a standard mouse) since many methods of exporting
guest graphics (such as VNC) work better in this mode. Note that
this is independent of the actual pointer device you are using on
the host/client side.
Host devices can also be passed through in this way, by specifying
host:USBID, where USBID is of the form xxxx:yyyy. The USBID can
typically be found by using lsusb or usb-devices.
The form usbdevice=DEVICE is also accepted for backwards
compatibility.
More valid options can be found in the "usbdevice" section of the
qemu documentation.
Device-Model Options
The following options control the selection of the device-model. This
is the component which provides emulation of the virtual devices to an
HVM guest. For a PV guest a device-model is sometimes used to provide
backends for certain PV devices (most usually a virtual framebuffer
device).
device_model_version="DEVICE-MODEL"
Selects which variant of the device-model should be used for this
guest. Valid values are:
qemu-xen
Use the device-model merged into the upstream QEMU project.
This device-model is the default for Linux dom0.
qemu-xen-traditional
Use the device-model based upon the historical Xen fork of
Qemu. This device-model is still the default for NetBSD dom0.
It is recommended to accept the default value for new guests. If
you have existing guests then, depending on the nature of the guest
Operating System, you may wish to force them to use the device
model which they were installed with.
device_model_override="PATH"
Override the path to the binary to be used as the device-model. The
binary provided here MUST be consistent with the
`device_model_version` which you have specified. You should not
normally need to specify this option.
device_model_stubdomain_override=BOOLEAN
Override the use of stubdomain based device-model. Normally this
will be automatically selected based upon the other features and
options you have selected.
device_model_stubdomain_seclabel="LABEL"
Assign an XSM security label to the device-model stubdomain.
device_model_args=[ "ARG", "ARG", ...]
Pass additional arbitrary options on the device-model command line.
Each element in the list is passed as an option to the device-
model.
device_model_args_pv=[ "ARG", "ARG", ...]
Pass additional arbitrary options on the device-model command line
for a PV device model only. Each element in the list is passed as
an option to the device-model.
device_model_args_hvm=[ "ARG", "ARG", ...]
Pass additional arbitrary options on the device-model command line
for an HVM device model only. Each element in the list is passed as
an option to the device-model.
Keymaps
The keymaps available are defined by the device-model which you are
using. Commonly this includes:
ar de-ch es fo fr-ca hu ja mk no pt-br sv
da en-gb et fr fr-ch is lt nl pl ru th
de en-us fi fr-be hr it lv nl-be pt sl tr
The default is en-us.
See qemu(1) for more information.
SEE ALSOxl(1)xlcpupool.cfg(5)
xl-disk-configuration
xl-network-configuration
docs/misc/tscmode.txt
FILES
/etc/xen/NAME.cfg /var/xen/dump/NAME
BUGS
This document may contain items which require further documentation.
Patches to improve incomplete items (or any other item) are gratefully
received on the xen-devel@lists.xen.org mailing list. Please see
<http://wiki.xen.org/wiki/SubmittingXenPatches> for information on how
to submit a patch to Xen.
4.3.0_14-1.3 2013-07-09 xl.cfg(5)
