.TH PLAN9.INI 8
.SH NAME
plan9.ini \- configuration file primarily for PCs
.SH SYNOPSIS
.I none
.SH DESCRIPTION
When booting Plan 9 on a PC, the bootstrap programs described in
.IR 9boot (8)
first read,
via TFTP or a FAT filesystem on the boot disk,
a file containing configuration information.
This file,
.BI /cfg/pxe/ hex-digits
(TFTP; see
.IR 9boot (8))
or
.B plan9.ini
(FAT),
looks like a shell script containing lines of the form
.IP
.EX
name=\f2value\fP
.EE
.LP
each of which defines a kernel or device parameter.
.PP
Blank lines and
Carriage Returns
.IB ( \er )
are ignored.
.B #
comments are ignored, but are only recognised if
.L #
appears at the start of a line.
.PP
For devices, the generic format of
.I value
is
.IP
.EX
type=TYPE [port=N] [irq=N] [mem=N] [size=N] [dma=N] [ea=N]
.EE
.LP
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.
.PP
The file is used by the bootstrap programs
and the kernel to configure the hardware available,
although nowadays the kernel can usually detect the attached hardware
by itself.
The information it contains is also passed to the boot
process, and subsequently other programs,
as environment variables
(see
.IR boot (8)).
However, values whose names begin with an asterisk
.L *
are used by the kernel and are stored in
.L #ec
rather than
.LR #e .
.PP
The following sections describe how variables are used.
.SS ETHERNET
.SS \fLetherX=\fIvalue
This defines an Ethernet interface.
.IR 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
.BR etherX+1 .
After probing as directed by the
.BI ether X
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
.LR *noetherprobe= .
.ig
This automatic probing is only done by the kernel, not by
the bootstrap programs.
Thus, if you want to load a kernel over the Ethernet, you need
to specify an
.B ether0
line so that
.I 9boot
can find the Ethernet card, even if the kernel would
have automatically detected it.
..
.PP
Many cards are software configurable and do not require all options.
Unspecified options default to the factory defaults.
.PP
Known
.IR TYPE s
are
.TF vt6102
.PD
.TP
.B igbe
The Intel 8254X Gigabit Ethernet controllers,
as found on the Intel PRO/1000 adapters for copper (not fiber).
Completely configurable.
.TP
.B igbepcie
The Intel 8256[36], 8257[12], and 82573[ev] Gigabit Ethernet
PCI-Express controllers.
Completely configurable.
.TP
.B rtl8169
The Realtek 8169 Gigabit Ethernet controller.
Completely configurable.
.TP
.B 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 configurable.
.TP
.B dp83820
National Semiconductor DP83820-based Gigabit Ethernet adapters, notably
the D-Link DGE-500T.
Completely configurable.
.TP
.B vgbe
The VIA Velocity Gigabit Ethernet controller.
Known to drive the VIA8237 (ABIT AV8), but at 100Mb/s full-duplex only.
.TP
.B m10g
The Myricom 10-Gigabit Ethernet 10G-PCIE-8A controller.
Completely configurable.
.TP
.B i82598
The Intel 8259[89] 10-Gigabit Ethernet PCI-Express controllers.
Completely configurable.
.TP
.B i82557
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)
.BR 10BASE-T ,
.BR 10BASE-2 ,
.BR 10BASE-5 ,
.BR 100BASE-TX ,
.BR 10BASE-TFD ,
.BR 100BASE-TXFD ,
.BR 100BASE-T4 ,
.BR 100BASE-FX ,
or
.BR 100BASE-FXFD .
Completely configurable.
.TP
.B 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
.BR i82557 .
Some cards using the
.B PNIC
and
.B PNIC2
near-clone chips may also work.
.TP
.B 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
.B ea=
attribute.
Completely configurable.
.TP
.B rtl8139
The Realtek 8139 Fast Ethernet controller.
Completely configurable.
.TP
.B vt6102
The VIA VT6102 Fast Ethernet Controller (Rhine II).
.TP
.B vt6105m
The VIA VT6105M Fast Ethernet Controller (Rhine III).
.TP
.B smc91cxx
SMC 91cXX chip-based PCMCIA adapters, notably the SMC EtherEZ card.
.TP
.B 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
.B media=
to the value
.BR 10BaseT ,
.BR 10Base2 ,
.BR 100BaseTX ,
.BR 100BaseFX ,
.BR aui ,
and
.BR mii .
If you need to force full duplex, because for example the Ethernet switch does not negotiate correctly,
just name the word (no value)
.B fullduplex
or
.BR 100BASE-TXFD .
Similarly, to force 100Mbit operation, specify
.BR force100 .
Port 0x110 is used for the little ISA configuration dance.
.TP
.B 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
.EX
	port=0x240 irq=10
.EE
The media may be specified as
.B media=10BaseT
or
.BR media=10Base2 .
.TP
.B 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 are
.EX
	port=0x300 irq=9
.EE
These cards are NE2000 clones.
Other NE2000 compatible PCMCIA cards may be tried
with the option
.EX
	id=string
.EE
where
.B string
is a unique identifier string contained in the attribute
memory of the card (see
.IR pcmcia (8));
unlike most options in
.BR plan9.ini ,
this string is case-sensitive.
The option
.B 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.
.TP
.B 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
.EX
	port=0x300 irq=2 mem=0x04000 size=0x4000
.EE
The option (no value)
.B nodummyrr
is needed on some (near) clones to turn off a dummy remote read in the driver.
.TP
.B amd79c970
The AMD PCnet PCI Ethernet Adapter (AM79C970).
(This is the Ethernet adapter used by VMware.)
Completely configurable, no options need be given.
.TP
.B 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
.EX
	port=0x280 irq=3 mem=0xD0000 size=0x2000
.EE
BUG: On many machines only the 16 bit card works.
.TP
.B sink
A
.B /dev/null
for Ethernet packets \(em the interface discards sent
packets and never receives any.
This is used to provide a test bed for
some experimental Ethernet bridging software.
.TP
.B wavelan
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.
.IP
These cards take a number of unique options to aid in
identifying the card correctly on the 802.11b network.
The network may be
.I "ad hoc"
or
.I managed
(i.e. use an access point):
.EX
	mode=[adhoc, managed]
.EE
and defaults to
.IR managed .
The 802.11b network to attach to
.RI ( managed
mode)
or identify as
.RI ( "ad hoc"
mode),
is specified by
.EX
	essid=string
.EE
and defaults to a null string.
The card station name is given by
.EX
	station=string
.EE
and defaults to
.IR "Plan 9 STA" .
The channel to use is given by
.EX
	channel=number
.EE
where
.I number
lies in the range 1 to 16 inclusive;
the channel is normally negotiated automatically.
.IP
If the card is capable of encryption,
the following options may be used:
.EX
	crypt=[off, on]
.EE
and defaults to
.IR on .
.EX
	key\fIN\fP=string
.EE
sets the encryption key
.I N
(where
.I N
is in the range 1 to 4 inclusive) to
.IR string ;
this will also set the transmit key to
.I N
(see below).
There are two formats for
.I 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
.IR 0x ).
The lengths are checked,
as is the format of a hex key.
.EX
	txkey=number
.EE
sets the transmit key to use to be
.I number
in the range 1 to 4 inclusive.
If it is desired to exclude or include unencrypted packets
.EX
	clear=[off, on]
.EE
configures reception and defaults to inclusion.
.IP
The defaults are intended to match the common case of
a managed network with encryption and a typical entry would
only require, for example
.EX
	essid=left-armpit key1=afish key2=calledraawaru
.EE
if the port and IRQ defaults are used.
These options may be set after boot by writing to the device's
.I ctl
file using a space as the separator between option and value, e.g.
.EX
	echo 'key2 1d8f65c9a52d83c8e4b43f94af' >/net/ether0/0/ctl
.EE
.IP
Card-specific power management may be enabled/disabled by
.EX
	pm=[on, off]
.EE
.TP
.B wavelanpci
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.
.
.SS DISKS, TAPES
(S)ATA controllers are autodetected.
.SS \fLusbX=type=uhci\fP
.SS \fLusbX=type=ohci\fP
.SS \fLusbX=type=ehci\fP
This specifies the settings for a USB UHCI, OHCI or EHCI controller.
Like the Ethernet controllers, USB controllers are autodetected
after scanning for the ones listed in
.IR plan9.ini .
Thus, most systems will not need a
.B usbX
line.
Also like the Ethernet controllers, USB autoprobing can be
disabled by specifying the line
.BR *nousbprobe= .
.SS \fLscsiX=\fIvalue
This defines a SCSI interface which cannot be automatically detected
by the kernel.
.PP
Known
.IR TYPE s 
are
.TP
.B aha1542
Adaptec 154x series of controllers (and clones).
Almost completely configurable, only the
.EX
	port=0x300
.EE
option need be given.
.PP
NCR/Symbios/LSI-Logic 53c8xx-based adapters
and Mylex MultiMaster (Buslogic BT-*) adapters are
automatically detected and need no entries.
.PP
By default, the NCR 53c8xx driver searches for up to 32 controllers.
This can be changed by setting the variable
.BR *maxsd53c8xx .
.PP
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
.BR *noscsireset
is defined, the SCSI bus reset flag is omitted.
.SS \fLaoeif=\fP\fIlist\fP
This specifies a space-separated
.I list
of Ethernet interfaces to be bound at boot to the ATA-over-Ethernet driver,
.IR aoe (3).
For example,
.LR "aoeif=ether0 ether1" .
Only interfaces on this list will initially be accessible via AoE.
.SS \fLaoedev=e!#æ/aoe/\fIshelf\fL.\fIslot\fR
This specifies an ATA-over-Ethernet device accessible via the interfaces
named in
.IR aoeif
on AoE
.I shelf
and
.I slot
to use as a root device for bootstrapping.
.SS AUDIO
.SS \fLaudioX=\fIvalue
This defines a pre-USB sound interface.
.PP
Known types are
.TF ess1688
.PD
.TP
.B sb16
Sound Blaster 16.
.TP
.B ess1688
A Sound Blaster clone.
.PP
The DMA channel may be any of 5, 6, or 7.
The defaults are
.IP
.EX
port=0x220 irq=7 dma=5
.EE
.SS Uarts
Plan 9 automatically configures COM1 and COM2, if found,
as
.B eia0
(port 0x3F8, IRQ4)
and
.B eia1
(port 0x2F8, IRQ3)
respectively.
These devices can be disabled by adding a line:
.IP
.EX
eia\fIX\fP=disabled
.EE
.LP
This is typically done in order to reuse the IRQ for
another device.
.PP
Plan 9 used to support various serial concentrators,
including the TTC 8 serial line card and various models
in the Star Gate Avanstar series of intelligent serial boards.
These are no longer supported; the much simpler
Perle PCI-Fast4, PCI-Fast8, and PCI-Fast16 controllers
have taken their places.
These latter cards are automatically detected
and need no configuration lines.
.PP
The line
.B serial=type=com
can be used to specify settings for a PCMCIA modem.
.SS \fLmouseport=\fIvalue
This specifies where the mouse is attached.
.I Value
can be
.TP
.B ps2
the PS2 mouse/keyboard port.  The BIOS setup procedure
should be used to configure the machine appropriately.
.TP
.B ps2intellimouse
an Intellimouse on the PS2 port.
.TP
.B 0
for COM1
.TP
.B 1
for COM2
.SS \fLmodemport=\fIvalue
Picks the UART line to call out on.
This is used when connecting to a file server over
an async line.
.I Value
is the number of the port.
.SS \fLconsole=\fIvalue params
This is used to specify the console device.
The default
value is
.BR cga ;
a number
.B 0
or
.B 1
specifies
.I COM1
or
.I COM2
respectively.
A serial console is initially configured with the
.IR uart (3)
configuration string
.B b9600
.B l8
.B pn
.BR s1 ,
specifying 9600 baud,
8 bit bytes, no parity, and one stop bit.
If
.I params
is given, it will be used to further
configure the uart.
Notice that there is no
.B =
sign in the
.I params
syntax.
For example,
.IP
.EX
console=0 b19200 po
.EE
.LP
would use COM1 at 19,200 baud
with odd parity.
.SS "PC CARD"
.SS \fLpccard0=disabled\fP
Disable probing for and automatic configuration of PC card controllers.
.SS \fLpcmciaX=type=XXX irq=\fIirq
If the default IRQ for the
PCMCIA
is correct, this entry can be omitted.  The value of
.B type
is ignored.
.SS \fLpcmcia0=disabled\fP
Disable probing for and automatic configuration of PCMCIA controllers.
.SS NVRAM
.SS \fLnvram=\fIfile\fP
.SS \fLnvrlen=\fIlength\fP
.SS \fLnvroff=\fIoffset\fP
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
.I readnvram
(see
.IR authsrv (2)).
The most common use of the nvram is to hold a
.IR secstore (1)
password for use by
.IR factotum (4).
.SS \fLnvr=\fIvalue
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
.B fd!0!plan9.nvr
(sic),
unless
.B bootfile
is set, in which case it is
.B plan9.nvr
on the same disk as
.BR bootfile .
The syntax is either
.BI fd! unit ! name
or
.BI hd! unit ! name
where
.I unit
is the numeric unit id.
This variant syntax is a vestige of the file server kernel's origins.
.SS BOOTING
.SS \fLbootfile=\fIvalue
This is used to direct the actions of
the bootstrap programs
by naming the device and file from which to load the kernel.
.SS \fLrootdir=\fIdir
.SS \fLrootspec=\fIspec
These are used by the bootstrap programs
to identify the directory
.I dir
to make the root directory for the kernel, and the
file system specifier
.I spec
(see
.B mount
in
.IR bind (2))
on which it can be found.
These are usually used to test variant file systems for distributions, etc.
.SS \fLbootargs=\fIargs
The value of this variable is passed to
.IR boot (8)
by the kernel as the name of the root file system.
It is typically used to specify additional arguments to
pass to
.IR kfs (4)
or
.IR ipconfig (8).
For example, if the system is to run from a local
.IR kfs (4)
partition, the definition might read
.BR bootargs=local!#S/sdC0/fs .
See
.IR boot (8)
for more.
.SS \fLnobootprompt=\fIroot
Suppress the
.L "root from"
prompt and use
.I root
as the answer instead.
.SS \fLuser=\fIuser
Suppress the
.L "user"
prompt and use
.I user
as the answer instead.
.SS \fLdebugfactotum=\fP
Causes
.IR boot (8)
to start
.I factotum
with the
.B -p
option, so that it can be debugged.
.SS \fLfactotumopts=\fIoptions
Causes
.IR boot (8)
to start
.I factotum
with the given
.IR options ,
which must be a single word (i.e., contain no whitespace).
.SS \fLventi=\fIvalue
When booting from a local fossil server backed by a local
or remote venti server,
this variable specifies how to establish the connection to the
venti server.
See
.IR boot (8)
for more.
.SS \fLcfs=\fIpartition
This names the file holding the disk partition
for the cache file system,
.IR cfs (4).
Extending the
.B bootargs
example, one would write
.BR cfs=#S/sdC0/cache .
.SS \fLbootdisk=\fIvalue
This deprecated variable was used to specify the disk used by
the cache file system and other disk-resident services.
It is superseded by
.B bootargs
and
.BR cfs .
.SS \fLpartition=\fIvalue
This defines the partition table
.IR 9load (8)
will examine to find disk partitioning information.
By default, a partition table in a Plan 9 partition
is consulted; if no such table is found, an old-Plan 9
partition table on the next-to-last or last sector
of the disk is consulted.
A value of
.B new
consults only the first table,
.B old
only the second.
.SS \fLreadparts=\fP
Causes
.IR boot (8)
to look for MBR and Plan 9 partition tables on all
.IR sd (3)
disks, even before
.I factotum
is started, so NVRAM, for example, may be found.
On PCs,
.I 9load
(but not
.IR 9boot )
normally does this and passes the partitions found in
.BR #ec/sd\fICn\fPpart .
.SS \fLfs=\fIa.b.c.d
.SS \fLauth=\fIa.b.c.d
These specify the IP address of the file and authentication server
to use when mounting a network-provided root file system.
They are used only if the addresses cannot be determined via DHCP.
.SS PROCESSOR
.SS \fL*norealmode=\fP
The PC kernel switches the processor to 16-bit real mode
to run BIOS interrupts, for example to find the memory map or to enable VESA.
This variable disables such switches.
.SS \fL*noe820scan=\fP
When available, the PC kernel uses the BIOS E820 memory map
to size memory.  This variable disables the scan.
.SS \fL*maxmem=\fIaddress
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
.B *maxmem
will limit the scan.
.B *maxmem
must be less than 3.75 gigabytes.
This variable is not consulted if using the E820 memory map.
.SS \fL*kernelpercent=\fIpercent
This defines the percentage of available memory reserved for the kernel allocation pool.
The remainder is left for user processes.  The default
.I percent
is
.B 30
on CPU servers,
.B 60
on terminals with less than 16MB of memory,
and
.B 40
on terminals with memories of 16MB or more.
Terminals use more kernel memory because
.IR draw (3)
maintains its graphic images in kernel memory.
This deprecated option is rarely necessary in newer kernels.
.SS \fL*nomce=\fIvalue
If machine check exceptions are supported by the processor,
then they are enabled by default.
Setting this variable to
.B 1
causes them to be disabled even when available.
.SS \fL*nomp=\fP
A multiprocessor machine will enable all processors by default.
Setting
.B *nomp
restricts the kernel to starting only one processor and using the
traditional interrupt controller.
.SS \fL*ncpu=\fIcpus\fP
Setting
.B *ncpu
restricts the kernel to starting at most
.I cpus
processors.
.SS \fL*pcimaxbno=\fIbno\fP
Limits the maximum bus number probed
on a PCI bus (default 7).
For example, a
.I bno
of 1 should suffice on a 'standard' motherboard with an AGP slot.
This, and
.B *pcimaxdno
below are rarely used and only on troublesome or suspect hardware.
.SS \fL*pcimaxdno=\fIdno\fP
Limits the maximum device number probed
on a PCI bus (default 31).
.SS \fL*nopcirouting=\fP
Disable pci routing during boot.  May solve interrupt routing
problems on certain machines.
.SS \fL*nodumpstack=\fP
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.
.\" .SS \fL*nobios=\fP
.\" what does this do?  something with pci
.SS \fLioexclude=\fIrange\fP
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:
.EX
    ioexclude=0x330-0x337,0x430-0x43F
.EE
.SS \fLumbexclude=\fIrange\fP
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:
.EX
    umbexclude=0xD1800-0xD3FFF
.EE
.SS \fLapm0=\fP
This enables the ``advanced power management'' interface
as described in
.IR apm (3)
and
.IR apm (8).
The main feature of the interface is the ability to watch
battery life (see
.IR stats (8)).
It is not on by default because it causes problems on some laptops.
.SS VIDEO
.SS \fLmonitor=\fImonitor
.SS \fLvgasize=\fIx\fPx\fIy\fPx\fId
These are used not by the kernel but by
.I termrc
(see
.IR cpurc (8))
when starting
.IR vga (8).
.SS \fL*dpms=\fIvalue
This is used to specify the screen blanking behavior of the MGA4xx
video driver.
Values are
.BR standby ,
.BR suspend ,
and
.BR off .
The first two specify differing levels of power saving;
the third turns the monitor off completely.
.SS Multiple Configurations
.PP
A
.B plan9.ini
file may contain multiple configurations,
each within a block beginning with a line
.EX
	[tag]
.EE
A special block with the tag
.B menu
gives a list of blocks from which the user may
interactively select the contents of
.BR plan9.ini .
There may also be multiple blocks with the tag
.B common
which will be included in all selections;
if any lines appear in
.B plan9.ini
before the first block,
they are treated as a
.B common
block.
.LP
Within the
.B menu
block the following configuration lines are allowed:
.SS \fLmenuitem=tag[, description]
The block identified by
.B tag
will appear in the presented menu.
The menu entry will consist of the
.B tag
unless the optional
.B description
is given.
.SS \fLmenudefault=tag[, timeout]
Identifies a default block to be given in the
menu selection prompt.
If the optional
.B timeout
is given (in seconds),
the default block will be selected if there is no user
input within the timeout period.
.SS \fLmenuconsole=value[, baud]
Selects a serial console upon which to present the menu
as no
.B console
or
.B baud
configuration information will have been processed yet
(the
.B plan9.ini
contents are still to be decided...).
.LP
In response to the menu being printed,
the user is prompted to select a menu item from the list.
If the numeric response is followed by a
.BR p ,
the selected configuration is printed and the menu presented
again.
.LP
The line
.EX
	menuitem=tag
.EE
is prefixed to the selected configuration as an aid to
user-level initialization scripts.
.br
.ne 4
.SH EXAMPLES
.PP
A representative
.BR plan9.ini :
.IP
.EX
% cat /n/c:/plan9.ini
ether0=type=3C509
mouseport=ps2
modemport=1
serial0=type=generic port=0x3E8 irq=5
monitor=445x
vgasize=1600x1200x8
%
.EE
.PP
Minimum CONFIG.SYS and AUTOEXEC.BAT files to use
COM2 as a console:
.IP
.EX
% cat /n/c:/config.sys
SHELL=COMMAND.COM COM2 /P
% cat /n/c:/autoexec.bat
@ECHO OFF
PROMPT $p$g
PATH C:\eDOS;C:\eBIN
mode com2:96,n,8,1,p
SET TEMP=C:\eTMP
%
.EE
.PP
Simple
.B plan9.ini
with multiple configurations:
.IP
.EX
[menu]
menuitem=vga, Plan 9 with VGA
menuitem=novga, Plan 9 no automatic VGA
menudefault=vga

[vga]
monitor=multisync135
vgasize=1024x768x8

[novga]

[common]
ether0=type=i82557
audio0=type=sb16 port=0x220 irq=5 dma=1
.EE
.PP
With this, the following menu will be presented on boot:
.IP
.EX
Plan 9 Startup Menu:
====================
    1. Plan 9 with VGA
    2. Plan 9 no automatic VGA
Selection[default==1]:
.EE
.PP
Selecting item 1 generates the following
.B plan9.ini
to be used by the remainder of the bootstrap process:
.IP
.EX
menuitem=vga
monitor=multisync135
vgasize=1024x768x8
ether0=type=i82557
audio0=type=sb16 port=0x220 irq=5 dma=1
.EE
.PP
and selecting item 2:
.IP
.EX
menuitem=novga
ether0=type=i82557
audio0=type=sb16 port=0x220 irq=5 dma=1
.EE
.SH "SEE ALSO"
.IR 9boot (8),
.IR booting (8),
.IR boot (8)
.SH BUGS
Being able to set the console device to other than a
display is marginally useful on file servers; MS-DOS
and the programs which run under it are so tightly bound
to the display that it is necessary to have a display if any
setup or reconfiguration programs need to be run.
Also, the delay before any messages appear at boot time
is disconcerting, as any error messages from the BIOS
are lost.
.PP
This idea is at best an interesting experiment that needs another iteration.