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      1 #	$NetBSD: README,v 1.3 2001/06/13 21:38:30 fredette Exp $
      2 
      3 README for ndbootd-0.5
      4 
      5 Copyright (c) 2001 Matthew Fredette.  All rights reserved.
      6 
      7 See the file COPYING for no-warranty and distribution terms.
      8 
      9 ndbootd is a daemon that serves Sun's old Network Disk (ND) protocol.
     10 This protocol was designed by Sun before they designed NFS.  ND simply
     11 makes the raw blocks of a disk available to network clients.  Contrast
     12 this with the true namespace and file abstractions that NFS provides.
     13 
     14 The only reason you're likely to encounter ND nowadays is if you have
     15 an old Sun-2 machine, like the 2/120 or 2/50.  The Sun-2 PROMs can
     16 only use ND to boot over the network.  (Later, the Sun-3 PROMs would
     17 use RARP and TFTP to boot over the network.)
     18 
     19 ndbootd is a very simple ND server that only supports client reads.
     20 
     21 usage: ndbootd [OPTIONS] BOOT1-BIN
     22 where OPTIONS are:
     23   -s, --boot2 { BOOT2-BIN | DIR }
     24                           find a second-stage boot program in the file
     25                           BOOT2-BIN or in the directory DIR
     26   -i, --interface NAME    use interface NAME
     27   -w, --window-size COUNT 
     28                           send at most COUNT unacknowledged packets [default=6]
     29   -d, --debug             set debug mode
     30 
     31 ndbootd exports a disk that the clients consider to be /dev/ndp0 (ND
     32 public unit zero).  The disk is available to any client listed in
     33 /etc/ethers (Sun-2 PROMs don't do RARP, but they do learn their IP
     34 address from the first ND response they receive from the server.)
     35 
     36 BOOT1-BIN is a file containing the mandatory first-stage network boot
     37 program.  The layout of the exported disk is:
     38 
     39 block 0: normally a Sun disklabel (but ignored by the PROM)
     40 blocks 1-15: the first-stage network boot program
     41 
     42 With the --boot2 option, ndbootd will also make a second-stage network
     43 boot program available to clients.  When --boot2 is used with a
     44 filename BOOT2-BIN, that file is the second-stage network boot program
     45 to be served to all clients.
     46 
     47 When --boot2 is used with a directory name DIR, ndbootd finds a
     48 client's second-stage network boot program by turning its IP address
     49 into a filename in that directory, in the same manner later Sun-3
     50 PROMs do when TFTPing (i.e., if a client has IP address 192.168.1.10,
     51 ndbootd expects to find DIR/C0A8010A.SUN2).  The expected use of
     52 --boot2 is with the /tftpboot directory, making ndbootd a functional
     53 replacement for tftp when used with an ND-aware first-stage boot
     54 program.
     55 
     56 Any second-stage network boot program always begins at block 16 of the
     57 exported disk, regardless of the length of the first-stage network
     58 boot program.
     59 
     60 Whether or not there is a second-stage network boot program, the
     61 exported disk appears to have infinite length.  The content of all
     62 blocks not used by the first- or second-stage network boot programs is
     63 undefined.
     64 
     65 All first- and second-stage network boot programs must have had their
     66 exec headers stripped off.
     67 
     68 Normally, ndbootd listens on the first up and running IP interface it
     69 finds.  Use the --interface option to give a specific interface.
     70 
     71 One parameter of the ND protocol is a sort of window size.  This is
     72 the number of 1-kilobyte packets that can be transmitted before
     73 waiting for an acknowledgement.  To change this from the default 6,
     74 use the --window-size option.
     75 
     76 When debug support is compiled in (it is by default), the --debug
     77 option turns on debugging.
     78 
     79 ndbootd has only been compiled and tested under NetBSD with BPF
     80 support, although there is a fair autoconf framework, and the raw
     81 interface support is broken out, which should allow for reasonable
     82 porting.
     83 
     84 Note that ndbootd was developed specifically to help me to boot my
     85 experimental NetBSD port on my Sun-2/120.  In this scenario, the
     86 first-stage network boot (bootyy) continues to use ND to load in the
     87 second-stage boot program (netboot), which can do a full
     88 RARP/bootparams/NFS boot.  (If the program netboot ever fit in 16
     89 blocks, we could eliminate bootyy, but this is unlikely.)
     90 
     91 (Aside: it is unusual for a network boot to have two stages of boot
     92 programs before the kernel; this is normally only done on real disks.
     93 But to the Sun-2 PROMs, /dev/ndp0 is just like a real disk in that it
     94 provides no EOF condition (like a tape boot gets, or like the Sun-3
     95 TFTP method gets), so it only loads a fixed number of blocks.)
     96 
     97 Whether ndbootd can be used to netboot SunOS on a Sun-2 is unknown, but
     98 the hope is that you can use the SunOS-provided sun2.bb file as the
     99 first-stage boot program, not use any --boot2 option, and ndbootd will
    100 perform as the SunOS ndbootd did.
    101 
    102 To configure ndbootd for compiling, run the 'configure' script,
    103 followed by make.  To report bugs in compiling or using ndbootd, email
    104 fredette (a] alum.mit.edu, and please include as much information as you
    105 can about what you're trying to do and what goes wrong.  I don't have
    106 much time to do support, but I'll try.
    107