When booting Plan 9 on a PC, the bootloader program 9boot(8) first
reads configuration information from a file on the boot media.
This file, plan9.ini, looks like a shell script containing lines
of the form|
each of which defines a kernel or device parameter.
Blank lines and Carriage Returns (\r) are ignored. # comments
are ignored, but are only recognised if # appears at the start
of a line.
For devices, the generic format of value is
specifying the controller type, the base I/O port of the interface,
its interrupt level, the physical starting address of any mapped
memory, the length in bytes of that memory, the DMA channel, and
for Ethernets an override of the physical network address. Not
all elements are relevant to all devices; the relevant values
and their defaults are defined below in the description of each
type=TYPE [port=N] [irq=N] [mem=N] [size=N] [dma=N] [ea=N]|
The file is used by the kernel to configure the hardware available.
The information it contains is also passed to the boot process,
and subsequently other programs, as environment variables (see
boot(8)). However, values whose names begin with an asterisk *
are used by the kernel and are not converted into
The following sections describe how variables are used.
This defines an Ethernet interface. X, a unique monotonically
increasing number beginning at 0, identifies an Ethernet card
to be probed at system boot. Probing stops when a card is found
or there is no line for etherX+1. After probing as directed by
the etherX lines, any remaining Ethernet cards that can be
automatically detected are added. Almost all cards can be automatically
detected. For debugging purposes, automatic probing can be disabled
by specifying the line *noetherprobe=.
Some cards are software configurable and do not require all options.
Unspecified options default to the factory defaults.
Known TYPEs are
igbe The Intel 8254X Gigabit Ethernet controllers, as found on
the Intel PRO/1000 adapters for copper (not fiber). Completely
rtl8169The Realtek 8169 Gigabit Ethernet controller. Completely
The Intel 8256, 8257, and 82573[ev] Gigabit Ethernet PCI–Express
controllers. Completely configurable.|
ga620 Netgear GA620 and GA620T Gigabit Ethernet cards, and other
cards using the Alteon Acenic chip such as the Alteon Acenic fiber
and copper cards, the DEC DEGPA–SA and the SGI Acenic. Completely
dp83820National Semiconductor DP83820–based Gigabit Ethernet adapters,
notably the D–Link DGE–500T. Completely configurable.
vgbe The VIA Velocity Gigabit Ethernet controller. Known to drive
the VIA8237 (ABIT AV8), but at 100Mb/s full–duplex only.
m10g The Myricom 10–Gigabit Ethernet 10G–PCIE–8A controller. Completely
configurable. Can't boot through these due to enormous firmware
i82598 The Intel 8259 10–Gigabit Ethernet PCI–Express controllers.
i82557 Cards using the Intel 8255 Fast Ethernet PCI Bus LAN
Controller such as the Intel EtherExpress PRO/100B. Completely
configurable, no options need be given. If you need to force the
media, specify one of the options (no value) 10BASE–T, 10BASE–2,
10BASE–5, 100BASE–TX, 10BASE–TFD,
2114x Cards using the Digital Equipment (now Intel) 2114x PCI Fast
Ethernet Adapter Controller, for example the Netgear FA310. Completely
configurable, no options need be given. Media can be specified
the same was as for the i82557. Some cards using the PNIC and
PNIC2 near–clone chips may also work.
83815 National Semiconductor DP83815–based adapters, notably the
Netgear FA311, Netgear FA312, and various SiS built–in controllers
such as the SiS900. On the SiS controllers, the Ethernet address
is not detected properly; specify it with an ea= attribute. Completely
rtl8139The Realtek 8139 Fast Ethernet controller. Completely configurable.
100BASE–TXFD, 100BASE–T4, 100BASE–FX, or 100BASE–FXFD. Completely
vt6102 The VIA VT6102 Fast Ethernet Controller (Rhine II).
elnk3 The 3COM Etherlink III series of cards including the 5x9,
59x, and 905 and 905B. Completely configurable, no options need
be given. The media may be specified by setting media= to the
value 10BaseT, 10Base2, 100BaseTX, 100BaseFX, aui, and mii. If
you need to force full duplex, because
SMC 91cXX chip–based PCMCIA adapters, notably the SMC EtherEZ card.|
3c589 The 3COM 3C589 series PCMCIA cards, including the 3C562 and
the 589E. There is no support for the modem on the 3C562. Completely
configurable, no options need be given. Defaults are
for example the Ethernet switch does not negotiate correctly,
just name the word (no value) fullduplex or 100BASE–TXFD. Similarly,
to force 100Mbit operation, specify force100. Port 0x110 is used
for the little ISA configuration dance.|
ec2t The Linksys Combo PCMCIA EthernetCard (EC2T), EtherFast 10/100
PCMCIA cards (PCMPC100) and integrated controllers (PCM100), the
Netgear FA410TX 10/100 PCMCIA card and the Accton EtherPair–PCMCIA
(EN2216). Completely configurable, no options need be given. Defaults
The media may be specified as media=10BaseT or media=10Base2.
ne2000 Not software configurable iff ISA; PCI clones or supersets
are software configurable; includes the Realtek 8029 clone used
by Parallels. 16–bit card. Defaults are
These cards are NE2000 clones. Other NE2000 compatible PCMCIA
cards may be tried with the option
where string is a unique identifier string contained in the attribute
memory of the card (see pcmcia(8)); unlike most options in plan9.ini,
this string is case–sensitive. The option dummyrr= can be used
to turn off (0) or on (1) a dummy remote read in the driver in
such cases, depending on how
NE2000 compatible they are.
port=0x300 irq=2 mem=0x04000 size=0x4000|
The option (no value) nodummyrr is needed on some (near) clones
to turn off a dummy remote read in the driver.
wd8003 Includes WD8013 and SMC Elite and Elite Ultra cards. There
are varying degrees of software configurability. Cards may be
in either 8–bit or 16–bit slots. Defaults are
The AMD PCnet PCI Ethernet Adapter (AM79C970). (This is the Ethernet
adapter used by VMware.) Completely configurable, no options need
bcm Broadcom BCM57xx Gigabit Ethernet controllers. Completely configurable,
no options need be given.
port=0x280 irq=3 mem=0xD0000 size=0x2000|
BUG: On many machines only the 16 bit card works.
yuk Marvell 88e8057 Yukon2 Gigabit Ethernet controller. Completely
configurable, no options need be given.
virtio Virtual Ethernet interface provided by QEMU/KVM and VirtualBox.
No options need be given. The MAC address can be changed with
the ea= option.
sink A /dev/null for Ethernet packets -- the interface discards sent
packets and never receives any. This is used to provide a test
bed for some experimental Ethernet bridging software.
wavelanLucent Wavelan (Orinoco) IEEE 802.11b and compatible PCMCIA
cards. Compatible cards include the Dell TrueMobile 1150 and the
Linksys Instant Wireless Network PC Card. Port and IRQ defaults
are 0x180 and 3 respectively.
These cards take a number of unique options to aid in identifying
the card correctly on the 802.11b network. The network may be
ad hoc or managed (i.e. use an access point):|
and defaults to managed. The 802.11b network to attach to (managed
mode) or identify as (ad hoc mode), is specified by
and defaults to a null string. The card station name is given
and defaults to Plan 9 STA. The channel to use is given by
where number lies in the range 1 to 16 inclusive; the channel
is normally negotiated automatically.
If the card is capable of encryption, the following options may
and defaults to on.
sets the encryption key N (where N is in the range 1 to 4 inclusive)
to string; this will also set the transmit key to N (see below).
There are two formats for string which depend on the length of
the string. If it is exactly 5 or 13 characters long it is assumed
to be an alphanumeric key; if it is exactly 10 or 26
characters long the key is assumed to be in hex format (without
a leading 0x). The lengths are checked, as is the format of a
sets the transmit key to use to be number in the range 1 to 4
inclusive. If it is desired to exclude or include unencrypted
configures reception and defaults to inclusion.
The defaults are intended to match the common case of a managed
network with encryption and a typical entry would only require,
essid=left–armpit key1=afish key2=calledraawaru
if the port and IRQ defaults are used. These options may be set
after boot by writing to the device's ctl file using a space as
the separator between option and value, e.g.
echo 'key2 1d8f65c9a52d83c8e4b43f94af' >/net/ether0/0/ctl
Card–specific power management may be enabled/disabled by
iwl Intel Wireless WiFi Link mini PCI–Express adapters require firmware
from http://firmware.openbsd.org/firmware/*/iwn–firmware*.tgz to
be present on attach in /lib/firmware or /boot. To limit the selected
APs the options essid= and bssid= may be set at boot or in the
PCI Ethernet adapters that use the same Wavelan programming interface.
Currently the only tested cards are those based on the Intersil
Prism 2.5 chipset.|
rt2860 Ralink Technology PCI/PCI–Express wireless adapters require
firmware from http://firmware.openbsd.org/firmware/*/ral–firmware*.tgz
to be present on attach in /lib/firmware or /boot. See iwl section
above for configuration details.
ether interface clone file using a space as the separator between
option and value, e.g.|
echo essid left–armpit >/net/ether1/clone
Scan results appear in the ifstats file and can be read out like:
Ad–hoc mode or WEP encryption is currently not supported.
wpi Intel PRO Wireless 3945abg PCI/PCI–Express wireless adapters
require firmware from http://firmware.openbsd.org/firmware/*/wpi–firmware*.tgz
to be present on attach in /lib/firmware or /boot. See iwl section
above for configuration details.
WPA/WPA2 encryption is detected automatically and a prompt for
the password will appear when using the WIFI interface for netbooting.
To avoid the prompt, the password can be specified with the boot
Disable automatic IPv6 configuration from incoming router advertisements.
PCI based controllers such as (S)ATA and NVMe are autodetected.
disables dma on ata devices.
explicitly enables dma on a specific ata device.
This defines a SCSI interface which cannot be automatically detected
by the kernel.
Known TYPEs are
NCR/Symbios/LSI–Logic 53c8xx–based adapters and Mylex MultiMaster
(Buslogic BT–*) adapters are automatically detected and need no
Adaptec 154x series of controllers (and clones). Almost completely
configurable, only the|
option need be given.
By default, the NCR 53c8xx driver searches for up to 32 controllers.
This can be changed by setting the variable *maxsd53c8xx.
By default the Mylex driver resets SCSI cards by using both the
hard reset and SCSI bus reset flags in the driver interface. If
a variable *noscsireset is defined, the SCSI bus reset flag is
This specifies a space–separated list of Ethernet interfaces to
be bound at boot to the ATA–over–Ethernet driver, aoe(3). For example,
aoeif=ether0 ether1. Only interfaces on this list will initially
be accessible via AoE.
This specifies an ATA–over–Ethernet device accessible via the interfaces
named in aoeif on AoE shelf and slot to use as a root device for
X=address size sectorsize
This reserves physical memory as a ramdisk that will appear as
sd(3) device sdZX. When the address argument is omited or zero,
then the ramdisk will be allocated from the top of physical memory.
This defines a sound interface. PCI–based audio devices such as
Intel HD audio or AC97 are autodetected and do not require any
Known types are
hda Intel HD audio.
ac97 AC97 based card.
sb16 Sound Blaster 16.
ess1688 A Sound Blaster clone.
The DMA channel may be any of 5, 6, or 7. The defaults are
This is typically done in order to reuse the IRQ for another device.
Plan 9 automatically configures COM1 and COM2, if found, as eia0
(port 0x3F8, IRQ4) and eia1 (port 0x2F8, IRQ3) respectively. These
devices can be disabled by adding a line:
Additional i8250 (ISA) uarts (uart2 to uart5) can be configured
Perle PCI–Fast4, PCI–Fast8, and PCI–Fast16 controllers are automatically
detected and need no configuration lines.
uartX=type=isa port=port irq=irq|
The line serial=type=com can be used to specify settings for a
would use COM1 at 19,200 baud with odd parity.
This is used by the kernel and 9boot(8) to specify the console
device. A number 0 or 1 specifies COM1 or COM2 respectively. A
serial console is initially configured with the uart(3) configuration
string b9600 l8 pn s1, specifying 9600 baud, 8 bit bytes, no parity,
and one stop bit. If params is given, it will be used
by the kernel to further configure the uart. Due to BIOS limitations,
9boot(8) ignores params and always assumes the default configuration.
Notice that there is no = sign in the params syntax. For example,
The value net specifies ``netconsole'' which sends console messages
as UDP packets over the network. It bypasses the IP stack and
writes Ethernet packets directly to the NIC. In this case params
is mandatory and takes the form
Srcip, srcport (default 6665), dstip and dstport (default 6666)
specify the source IP address, source port, destination IP address
and destination port, respectively. Devno (default 0) specifies
which NIC to use, a value of n corresponds to NIC at #ln (see
ether(3)). Dstmac specifies the destination MAC address; broadcast
packets are sent if it is unspecified. Note that it is possible,
but not recommended, to send packets to a host outside the local
network by specifying the MAC address of the gateway as dstmac.
Example lines are
srcip [ !srcport ] [ /devno ] , dstip [ !dstport ] [ /dstmac ]
USB keyboards are automatically detected.
This inhibits the kernel and 9boot(8) from reading from the PS2
This specifies the keyboard map to use. Value can be a map file
found in /sys/lib/kbmap on the ramdisk.
USB mice are automatically detected.
This specifies where the mouse is attached.
ps2 the PS2 mouse/keyboard port. The BIOS setup procedure should
be used to configure the machine appropriately.
0 for COM1
an Intellimouse on the PS2 port.|
1 for COM2
Disable probing for and automatic configuration of PC card controllers.
If the default IRQ for the PCMCIA is correct, this entry can be
omitted. The value of type is ignored.
Disable probing for and automatic configuration of PCMCIA controllers.
This is used to direct the actions of 9boot(8) by naming the file
from which to load the kernel in the current BIOS boot device.
The value of this variable is passed to boot(8) by the kernel
as the name of the root file system to automatically mount and
boot into. It is typically used to specify additional arguments
to pass to cwfs(4) or ipconfig(8). For example, if the system
is to run from a local cwfs(4) partition, the definition might
bootargs=local!/dev/sdC0/fscache. See boot(8) for more.
Suppress the bootargs prompt and use value as the answer instead.
Always use value as the answer to the bootargs prompt, retrying
Changes the mount arguments for the root file server that was
specified by bootargs above. By changing dir in $rootdir, a different
sub–directory on the root file server can be used as the system
root. see boot(8) for details.
Suppress the user prompt and use value as the answer instead.
Changes the systems default role. Possible settings for value
are cpu and terminal.
Causes boot(8) to start factotum with the –p option, so that it
can be debugged.
This gives the name of the file holding the disk partition for
the cache file system, cfs(4). Extending the bootargs example,
one would write cfs=#S/sdC0/cache.
This deprecated variable was used to specify the disk used by
the cache file system and other disk–resident services. It is superseded
by bootargs and cfs.
These specify the network address (IP or domain name) of the file,
authentication and secstore server to use when mounting a network–provided
root file system. When not specified, then these settings are
determined via DHCP. When secstore is not specified, then the
authentication server is used.
*e820=type 0xstart 0xend ...
This variable is automatically generated by the boot loader (see
9boot(8)) by doing a BIOS E820 memory scan while still in realmode
and passed to the kernel. The format is an unordered list of decimal
region type and hexadecimal 64–bit start and end addresses of the
Specifies a list of ranges of UMB to exclude from use by drivers.
Ranges are inclusive on both ends and separated by commas. For
This defines the maximum physical address that the system will
scan when sizing memory. By default the PC operating system will
scan up to 3.75 gigabytes (0xF0000000, the base of kernel virtual
address space), but setting *maxmem will limit the scan. *maxmem
must be less than 3.75 gigabytes. This variable is
not consulted if using the E820 memory map.
This defines what percentage of available memory is reserved for
the kernel allocation pool. The remainder is left for user processes.
The default value is 30 on CPU servers, 60 on terminals with less
than 16MB of memory, and 40 on terminals with memories of 16MB
or more. Terminals use more kernel memory
because draw(3) maintains its graphic images in kernel memory.
This deprecated option is rarely necessary in newer kernels.
This limits the maximum amount of memory (in megabytes) the graphics
image memory pool can grow. The default is unlimited for terminals
and cpu servers.
Disables AVX and AVX2 on AMD64 CPUs.
If machine check exceptions are supported by the processor, then
they are enabled by default. Setting *nomce causes them to be
disabled even when available.
A multiprocessor machine will enable all processors by default.
Setting *nomp restricts the kernel to starting only one processor
and using the traditional interrupt controller.
Setting *ncpu restricts the kernel to starting at most value processors.
Prints a summary of the multiprocessor APIC interrupt configuration.
Disables message signaled interrupts for PCI devices. This option
has no effect when *nomp is set.
Disables memory type range register (MTRR) support when set. (debug)
Disables the use of the per processor timestamp counter registers
as high resolution clock.
Disables the HPET timer to be used as the high resolution clock.
This puts a limit on the maximum bus number probed on a PCI bus
(default 7). For example, a value of 1 should suffice on a 'standard'
motherboard with an AGP slot. This, and *pcimaxdno below are rarely
used and only on troublesome or suspect hardware.
This puts a limit on the maximum device number probed on a PCI
bus (default 31).
Disable pci routing during boot. May solve interrupt routing problems
on certain machines.
Prints a summary of the detected PCI busses and devices.
Prevents cpu servers from rebooting on kernel panic, to enable
inspection of panic messages.
Disable printing a stack dump on panic. Useful if there is only
a limited cga screen available, otherwise the textual information
about the panic may scroll off.
This option controls the search for ACPI tables by the kernel.
The value is the hexadecimal physical address of the RSD structure
and is passed by the EFI bootloer 9boot(8) automatically. The
special value of 1 or empty make the kernel search for the structure
in BIOS memory area (This is the default). The special value
of 0 will disable ACPI support (for interrupt routing) in the
kernel, but still make table data available in #P/acpitbls file
of the arch(3) device.
This enables the ``advanced power management'' interface as described
in apm(3) and apm(8). The main feature of the interface is the
ability to watch battery life (see stats(8)). It is not on by
default because it causes problems on some laptops.
Specifies a list of ranges of I/O ports to exclude from use by
drivers. Ranges are inclusive on both ends and separated by commas.
Disable USB host controller detection.
Disable specific USB host controller types.
Disable nusbrc(8) startup at boot time.
When defined, nusbrc(8) will use the dynamically assigned usb
device address to name usb devices instead of the device unique
This inhibits the kernel and 9boot(8) from using the CGA text
These are used not by the kernel but by screenrc which is called
from termrc (see cpurc(8)) when starting vga(8). If value is set
to ask then the user is prompted for a choice on boot.
This is used by the kernel to attach a pre–initialized linear framebuffer
that was setup by the bootloader or firmware. The value has four
space separated fields: the resolution and bitdepth of the screen,
the color channel descriptor, the physical address of the framebuffer
and a optional aperture size.
*bootscreen=800x600x32 x8r8g8b8 0x80000000 0x001d4c00|
This is used to specify the screen blanking behavior of the MGA4xx
video driver. Values are standby, suspend, and off. The first
two specify differing levels of power saving; the third turns
the monitor off completely.
This is used to orient the screen on startup. Values are left,
right, inverted, and none. If no value is given, the default is
This is used to specify an nvram device and optionally the length
of the ram and read/write offset to use. These values are consulted
by readnvram (see authsrv(2)). The most common use of the nvram
is to hold a secstore(1) password for use by factotum(4).
This is used by the WORM file server kernel to locate a file holding
information to configure the file system. The file cannot live
on a SCSI disk. The default is fd!0!plan9.nvr (sic), unless bootfile
is set, in which case it is plan9.nvr on the same disk as bootfile.
The syntax is either fd!unit!name or
hd!unit!name where unit is the numeric unit id. This variant syntax
is a vestige of the file server kernel's origins.