107 lines
4.7 KiB
Plaintext
107 lines
4.7 KiB
Plaintext
# $NetBSD: README,v 1.2 2001/05/22 14:41:59 fredette Exp $
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README for ndbootd-0.1
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Copyright (c) 2001 Matthew Fredette. All rights reserved.
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See the file COPYING for no-warranty and distribution terms.
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ndbootd is a daemon that serves Sun's old Network Disk (ND) protocol.
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This protocol was designed by Sun before they designed NFS. ND simply
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makes the raw blocks of a disk available to network clients. Contrast
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this with the true namespace and file abstractions that NFS provides.
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The only reason you're likely to encounter ND nowadays is if you have
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an old Sun-2 machine, like the 2/120 or 2/50. The Sun-2 PROMs can
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only use ND to boot over the network. (Later, the Sun-3 PROMs would
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use RARP and TFTP to boot over the network.)
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ndbootd is a very simple ND server that only supports client reads.
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usage: ndbootd [OPTIONS] BOOT1-BIN
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where OPTIONS are:
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-s, --boot2 { BOOT2-BIN | DIR }
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find a second-stage boot program in the file
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BOOT2-BIN or in the directory DIR
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-i, --interface NAME use interface NAME
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-w, --window-size COUNT
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send at most COUNT unacknowledged packets [default=6]
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-d, --debug set debug mode
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ndbootd exports a disk that the clients consider to be /dev/ndp0 (ND
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public unit zero). The disk is available to any client listed in
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/etc/ethers (Sun-2 PROMs don't do RARP, but they do learn their IP
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address from the first ND response they receive from the server.)
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BOOT1-BIN is a file containing the mandatory first-stage network boot
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program. The layout of the exported disk is:
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block 0: normally a Sun disklabel (but ignored by the PROM)
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blocks 1-15: the first-stage network boot program
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With the --boot2 option, ndbootd will also make a second-stage network
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boot program available to clients. When --boot2 is used with a
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filename BOOT2-BIN, that file is the second-stage network boot program
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to be served to all clients.
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When --boot2 is used with a directory name DIR, ndbootd finds a
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client's second-stage network boot program by turning its IP address
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into a filename in that directory, in the same manner later Sun-3
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PROMs do when TFTPing (i.e., if a client has IP address 192.168.1.10,
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ndbootd expects to find DIR/C0A8010A.SUN2). The expected use of
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--boot2 is with the /tftpboot directory, making ndbootd a functional
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replacement for tftp when used with an ND-aware first-stage boot
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program.
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Any second-stage network boot program always begins at block 16 of the
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exported disk, regardless of the length of the first-stage network
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boot program.
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Whether or not there is a second-stage network boot program, the
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exported disk appears to have infinite length. The content of all
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blocks not used by the first- or second-stage network boot programs is
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undefined.
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All first- and second-stage network boot programs must have had their
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exec headers stripped off.
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Normally, ndbootd listens on the first up and running IP interface it
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finds. Use the --interface option to give a specific interface.
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One parameter of the ND protocol is a sort of window size. This is
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the number of 1-kilobyte packets that can be transmitted before
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waiting for an acknowledgement. To change this from the default 6,
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use the --window-size option.
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When debug support is compiled in (it is by default), the --debug
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option turns on debugging.
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ndbootd has only been compiled and tested under NetBSD with BPF
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support, although there is a fair autoconf framework, and the raw
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interface support is broken out, which should allow for reasonable
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porting.
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Note that ndbootd was developed specifically to help me to boot my
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experimental NetBSD port on my Sun-2/120. In this scenario, the
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first-stage network boot (bootyy) continues to use ND to load in the
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second-stage boot program (netboot), which can do a full
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RARP/bootparams/NFS boot. (If the program netboot ever fit in 16
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blocks, we could eliminate bootyy, but this is unlikely.)
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(Aside: it is unusual for a network boot to have two stages of boot
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programs before the kernel; this is normally only done on real disks.
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But to the Sun-2 PROMs, /dev/ndp0 is just like a real disk in that it
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provides no EOF condition (like a tape boot gets, or like the Sun-3
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TFTP method gets), so it only loads a fixed number of blocks.)
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Whether ndbootd can be used to netboot SunOS on a Sun-2 is unknown, but
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the hope is that you can use the SunOS-provided sun2.bb file as the
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first-stage boot program, not use any --boot2 option, and ndbootd will
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perform as the SunOS ndbootd did.
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To configure ndbootd for compiling, run the 'configure' script,
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followed by make. To report bugs in compiling or using ndbootd, email
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fredette@alum.mit.edu, and please include as much information as you
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can about what you're trying to do and what goes wrong. I don't have
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much time to do support, but I'll try.
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