.TH 9BOOT 8
.SH NAME
9bootfat, 9bootiso, 9bootpxe \- PC bootloader for FAT, ISO and PXE network booting
.SH SYNOPSIS
Started by PC BIOS or chainloaded by partition bootsector
.SH DESCRIPTION
9boot is the bootloader used on PCs to start the Plan 9 kernel.
Its task is to read and parse the
.IR plan9.ini (8)
configuration file, gather some basic system information like
the amount of usable system memory, do some basic system
initialization and load the kernel from the boot media into memory.

After reading the configuration, the loader will automatically 
attempt to boot the kernel that was specified by the
.B bootfile=
parameter. If there is no such parameter, a key
gets pressed on the keyboard or the kernel file was not
found then the loader enters the interactive
boot console.

The syntax of the boot console is the same as in
the
.IR plan9.ini (8)
file.
.BR
The word
.B clear
[
.I prefix
]
can be used to remove parameters from the current configuration.
If a
.IR prefix
is specified, the first parameter that matches the prefix
is removed. If the
.IR prefix
argument is omitted, the whole configuration will be reset.
The word
.B boot
will end the console and resume booting the kernel.

There are many ways to boot a PC so
.IR 9boot
was split into a number of distinct programs one for each boot
method.
.SH FAT BOOTING
When booting Plan 9 from a harddisk or USB pen drive, a
FAT16/32 partition
.IR (9fat) 
is used to store the kernel and 
.IR plan9.ini (8)
configuration. Due to size limitations, instead of loading
the kernel directly, the bootsector
.IR (pbs)
of the FAT partition loads
a 2nd stage bootloader 
.IR (9bootfat)
from the root directory of the filesystem.
.SH CD-ROM BOOTING
Booting from CD-ROM requires only the 
.IR 9bootiso
bootloader to be included in the ISO-9660 image under
.B 386/9bootiso,
set as a non-emulation bootblock (see
.IR mk9660 (8)).
Boot parameters are read from
.B cfg/plan9.ini.
.SH NETWORK BOOTING
With a PXE capable BIOS and network card one can download
.IR 9bootpxe
and boot the kernel from a TFTP server (see
.IR dhcpd (8)
and
.IR ndb (6)
for details). Once started,
.IR 9bootpxe
will read the file
.B /cfg/pxe/$ether
from the tftp server, where
.B $ether
is the MAC address of the client's network card
in lower case hex, and use this as its
.IR plan9.ini (8)
file.
.SH FILES
.B /386/pbs
.br
.B /386/9bootfat
.br
.B /386/9bootiso
.br
.B /386/9bootpxe
.SH SOURCE
.BR /sys/src/boot/pc
.SH "SEE ALSO"
.IR plan9.ini (8)