plan9.ini – configuration file for PCs




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


type=TYPE [port=N] [irq=N] [mem=N] [size=N] [dma=N] [ea=N]

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 device.

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 environment variables.

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


The Intel 8254X Gigabit Ethernet controllers, as found on the Intel PRO/1000 adapters for copper (not fiber). Completely configurable.  


The Intel 8256[36], 8257[12], and 82573[ev] Gigabit Ethernet PCI-Express controllers. Completely configurable.  


The Realtek 8169 Gigabit Ethernet controller. Completely configurable.  


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 configurable.  


National Semiconductor DP83820-based Gigabit Ethernet adapters, notably the D-Link DGE-500T. Completely configurable.  


The VIA Velocity Gigabit Ethernet controller. Known to drive the VIA8237 (ABIT AV8), but at 100Mb/s full-duplex only.  


The Myricom 10-Gigabit Ethernet 10G-PCIE-8A controller. Completely configurable. Can’t boot through these due to enormous firmware loads.  


The Intel 8259[89] 10-Gigabit Ethernet PCI-Express controllers. Completely configurable.  


Cards using the Intel 8255[789] 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, 100BASE-TXFD, 100BASE-T4, 100BASE-FX, or 100BASE-FXFD. Completely configurable.  


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.  


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 configurable.  


The Realtek 8139 Fast Ethernet controller. Completely configurable.  


The VIA VT6102 Fast Ethernet Controller (Rhine II).  


SMC 91cXX chip-based PCMCIA adapters, notably the SMC EtherEZ card.  


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 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.  


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  

	port=0x240 irq=10

The media may be specified as media=10BaseT or media=10Base2.


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 are  

	port=0x300 irq=9

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=[01] 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.


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  

	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.


The AMD PCnet PCI Ethernet Adapter (AM79C970). (This is the Ethernet adapter used by VMware.) Completely configurable, no options need be given.  


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  

	port=0x280 irq=3 mem=0xD0000 size=0x2000

BUG: On many machines only the 16 bit card works.


Broadcom BCM57xx Gigabit Ethernet controllers. Completely configurable, no options need be given.  


Marvell 88e8057 Yukon2 Gigabit Ethernet controller. Completely configurable, no options need be given.  


Virtual Ethernet interface provided by QEMU/KVM and VirtualBox. No options need be given. The MAC address can be changed with the ea= option.  


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.  


Lucent 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):  

	mode=[adhoc, managed]

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 by


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 be used:  

	crypt=[off, on]

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 hex key.


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 packets

	clear=[off, on]

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, for example  

	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  

	pm=[on, off]


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.  


Intel Wireless WiFi Link mini PCI-Express adapters require firmware from*/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 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:

	cat /net/ether1/ifstats

Ad-hoc mode or WEP encryption is currently not supported.


Ralink Technology PCI/PCI-Express wireless adapters require firmware from*/ral-firmware*.tgz to be present on attach in /lib/firmware or /boot. See iwl section above for configuration details.  


Intel PRO Wireless 3945abg PCI/PCI-Express wireless adapters require firmware from*/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 parameter above.


Disable automatic IPv6 configuration from incoming router advertisements.


(S)ATA controllers 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


Adaptec 154x series of controllers (and clones). Almost completely configurable, only the  


option need be given.

NCR/Symbios/LSI-Logic 53c8xx-based adapters and Mylex MultiMaster (Buslogic BT-*) adapters are automatically detected and need no entries.

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 omitted.


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 bootstrapping.


ramdiskX=size sectorsize

ramdiskX=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 settings.

Known types are


Intel HD audio.  


AC97 based card.  


Sound Blaster 16.  


A Sound Blaster clone.  

The DMA channel may be any of 5, 6, or 7. The defaults are


port=0x220 irq=7 dma=5


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:



This is typically done in order to reuse the IRQ for another device.

unhandled troff command .P

Additional i8250 (ISA) uarts (uart2 to uart5) can be configured using:


uartX=type=isa port=port irq=irq

Perle PCI-Fast4, PCI-Fast8, and PCI-Fast16 controllers are automatically detected and need no configuration lines.

The line serial=type=com can be used to specify settings for a PCMCIA modem.


This specifies where the mouse is attached. Value can be


the PS2 mouse/keyboard port. The BIOS setup procedure should be used to configure the machine appropriately.  


an Intellimouse on the PS2 port.  


for COM1  


for COM2  


Picks the UART line to call out on. This is used when connecting to a file server over an async line. Value is the number of the port.

console=value params

This is used to specify the console device. The default value is cga; 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 to further configure the uart. Notice that there is no = sign in the params syntax. For example,


console=0 b19200 po

would use COM1 at 19,200 baud with odd parity.

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 ] [ /devno ] , dstip [ !dstport ] [ /dstmac ]  

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





Disable probing for and automatic configuration of PC card controllers.

pcmciaX=type=XXX irq=value

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 read bootargs=local!/dev/sdC0/fscache. See boot(8) for more.


Suppress the bootargs prompt and use value as the answer instead.



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 a unordered list of decimal region type and hexadecimal 64-bit start and end addresses of the area.


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.


If machine check exceptions are supported by the processor, then they are enabled by default. Setting this variable to 1 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.


Disables the use of the per processor timestamp counter registers as 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.


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.


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. For example:



Specifies a list of ranges of UMB to exclude from use by drivers. Ranges are inclusive on both ends and separated by commas. For example:



The presence of this option enables ACPI and the export of the #P/acpitbls file in arch(3) device. In multiprocessor mode, the kernel will use the ACPI tables to configure APIC interrupts unless a value of 0 is specified.


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.



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 name.




These are used not by the kernel but by 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 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.


A representative plan9.ini:


% cat /n/9fat:/plan9.ini
serial0=type=generic port=0x3E8 irq=5


9boot(8), booting(8), boot(8)