9BOOT(8)                                                 9BOOT(8)

          9bootfat, 9bootiso, 9boothyb, 9bootpxe, bootia32.efi,
          bootx64.efi, efiboot.fat - PC bootloader for FAT, ISO and
          PXE network booting

          Started by PC BIOS/EFI or chainloaded by partition

          9boot is the bootloader used on PCs to start the Plan 9
          kernel.  Its task is to read and parse the plan9.ini(8) con-
          figuration 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

          After reading the configuration, the loader will automati-
          cally attempt to boot the kernel that was specified by the
          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
          plan9.ini(8) file with key=value pairs setting boot parame-
          ters. In addition a few command words are recognized that
          are intended for interactive use:

               can be used to remove parameters from the configura-
               tion.  If a prefix is specified, the first parameter
               that matches the prefix is removed. If the prefix argu-
               ment is omitted, the whole configuration will be reset.

          show displays the current configuration in memory.

          wait will return to the console prompt after processing the
               configuration file preventing automatic boot.

          boot will end the console and attempt booting the kernel.

          There are many ways to boot a PC so 9boot was split into a
          number of distinct programs one for each boot method.

          When booting Plan 9 from a harddisk or USB pen drive, a
          FAT16/32 partition (9fat) is used to store the kernel and
          plan9.ini(8) configuration. Due to size limitations, instead
          of loading the kernel directly, the bootsector (pbs) of the

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     9BOOT(8)                                                 9BOOT(8)

          FAT partition loads a 2nd stage bootloader (9bootfat) from
          the root directory of the filesystem.

          Booting from CD-ROM requires only the 9bootiso bootloader to
          be included in the ISO-9660 image under /386/9bootiso, set
          as a non-emulation bootblock (see -B in mk9660(8)). Boot
          parameters are read from /cfg/plan9.ini.

          With the 9boothyb loader, an ISO image can be made into a
          bootable disk by creating a MBR and appending a bootable DOS
          partition containing 9boothyb renamed to 9bootfat. The
          loader will read the ISO filesystem as if it were stored on
          a CD-ROM drive.

          With a PXE capable BIOS and network card one can download
          9bootpxe and boot the kernel from a TFTP server (see
          dhcpd(8) and ndb(6) for details). Once started, 9bootpxe
          will read the file /cfg/pxe/$ether or, if this file is not
          present, /cfg/pxe/default from the tftp server, where $ether
          is the MAC address of the client's network card in lower
          case hex, and uses this as its plan9.ini(8) file.

          EFI firmware looks for the files bootia32.efi (for 386) or
          bootx64.efi (for amd64) in the boot media and executes them.
          For local disk media, these files are located in the direc-
          tory /efi/boot of the FAT formatted boot partition.  For
          CD-ROM media, the boot partition is provided as a embedded
          FAT filesystem image efiboot.fat (see -E in mk9660(8)). In
          the network boot case, the bootia32.efi or bootx64.efi files
          are used as the BSP program instead of 9bootpxe. Once
          started, the boot media (PXE, ISO, FAT) is discovered and
          plan9.ini(8) configuration is read from it in the same way
          as with the BIOS-based 9boot* loaders.



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     9BOOT(8)                                                 9BOOT(8)

          plan9.ini(8), mk9660(8), dhcpd(8), ndb(6)

          9boot first appeared in 9front (April, 2011).  EFI support
          first appeared in 9front (Oct, 2014).

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