My system consists of a Linux server (basically Slackware-3.6 but with kernel 2.2.10 and various other irrelevant package upgrades) and 2 Sun3’s, only one of which is ever in use at any given time (thus they use the same swap partition on the server – later).
The Sun3’s are diskless and hence boot from the Linux box, and mount all filesystems from it. The Sun’s run NetBSD 1.3.2 largely because the Sun 3 port of Linux was not very stable or mature when I set things up.
OK, some basic info for future use:
|Host||Hostname||Ethernet addr||IP addr|
The boot process for the Suns is basically as follows:
- tell the machine to boot from the ethernet device
- it gets its IP address by rarp
- it uses tftp to get a 2nd stage boot program **whose name is the IP address of the client** from the server
- the 2nd stage boot loader gets boot parameters from the bootp server
- the boot parameters specify where the root filesystem, containing the kernel, is located.
- The boot loader nfs-mounts this remote root f/s and boots the kernel.
- Once it has its root f/s the boot process is pretty standard as per a diskful machine.
OK, in more detail:
Power on machine, hit
L1-A if necessary to get a monitor prompt
Enter boot command, specifying ethernet interface as the boot device:
> b le(0,0,0)
First thing that happens is the machine broadcasts rarp requests saying “This is my ethernet addr, can somebody tell me my IP address please”.
My linux kernel is compiled with rarp support, and the kernel rarp table is populated at boot time by the following commands in rc.local:
rarp -s hermon 08:00:20:00:49:16 rarp -s carmel 08:00:20:06:1F:50
(/etc/hosts on moriah contains entries for hermon and carmel so the names are resolvable to numeric addresses)
(the forward-mapping arp table is also set up at boot time on moriah by
"arp -f /etc/ethers" command – sadly rarp has no corresponding
-foption so each entry must be added individually).
On receiving a response from moriah to the rarp request, the Sun contacts the tftp server on moriah and attempts to download the file
/tftpboot/<my-IP-addr> from it. /tftpboot on moriah looks like:
moriah% ls -lF /tftpboot/ total 16 lrwxrwxrwx 1 root root 7 Aug 3 23:00 C0A8C802 -> netboot* lrwxrwxrwx 1 root root 7 Aug 3 23:00 C0A8C803 -> netboot* -rwxr-xr-x 1 root root 15360 Aug 1 22:56 netboot*
netboot is the NetBSD stage 2 boot program. IP addresses are in hex as you can see.
The tftp server
in.tftpd runs from inetd on moriah – the relevant line from
moriah% grep tftp /etc/inetd.conf tftp dgram udp wait nobody /usr/sbin/in.tftpd in.tftpd
and from /etc/services:
moriah% grep tftp /etc/services tftp 69/udp
Once dowloaded, the stage 2 boot program executes: its first task is to get its boot parameters from the bootp server. I had trouble getting the bootpd program which came with Slackware to work so I replaced it with bootparamd from the NetKit.
bootparamd runs as a daemon, but could just as well run from inetd. It uses the file /etc/bootparams to hold boot config information:
moriah% cat /etc/bootparams hermon root=moriah:/export/root/hermon swap=moriah:/export/swap carmel root=moriah:/export/root/carmel swap=moriah:/export/swap
All that is specified in this case is the root and swap partitions for each of the 2 Sun’s – as I said they share a swap partition as only one is ever up at any one time.
From then on it’s plain sailing (you must of course have nfs working on the server so the clients can mount the filesystems). The boot loader mounts the root fs from the server, and loads the kernel (which in the case of NetBSD must be
/netbsd – I only found this out by trial and error). The root fs in my case contains everything, but there’s no reason why you shouldn’t nfs mount other filesystems in the usual way of course once the kernel boots. Here’s the contents of
moriah% ls -lF /export/root/hermon total 3955 drwxr-xr-x 2 root root 1024 Jan 5 1998 altroot/ drwxr-xr-x 2 root root 1024 Jan 5 1998 bin/ -rw------- 1 root root 458752 Aug 10 19:26 core drwxr-xr-x 3 root root 5120 Aug 17 01:35 dev/ drwxr-xr-x 8 root root 2048 Aug 14 15:26 etc/ -rw------- 1 root root 16656 Aug 13 15:58 getty.core drwxr-xr-x 3 root root 1024 Aug 13 15:55 home/ drwxr-xr-x 2 root root 1024 Dec 6 1997 mnt/ lrwxrwxrwx 1 root root 13 Aug 14 05:56 netbsd -> netbsd.hermon* -rw-r--r-- 1 root root 1025115 Aug 2 21:34 netbsd-gen -rw-r--r-- 1 root root 769619 Aug 2 21:34 netbsd-inst -rw-r--r-- 1 root root 983596 Aug 2 21:35 netbsd-rd -rwxr-xr-x 1 root root 750847 Aug 14 05:56 netbsd.hermon* drwxr-xr-x 2 root root 1024 Aug 10 00:21 proc/ drwxr-xr-x 3 root root 1024 Aug 10 00:03 root/ drwxr-xr-x 2 root root 2048 Jan 5 1998 sbin/ drwxr-xr-x 2 root root 1024 Dec 19 1997 stand/ drwxr-xr-x 2 root root 1024 Aug 13 16:06 swap/ lrwxrwxrwx 1 root root 11 Aug 10 00:02 sys -> usr/src/sys/ drwxrwxrwt 3 root root 1024 Aug 17 01:18 tmp/ drwxr-xr-x 15 root root 1024 Aug 13 15:45 usr/ drwxr-xr-x 19 root root 1024 Dec 6 1997 var/
There’s a few old kernels lying aroud, the one in use I configured and built for this machine. The only other thing that I had trouble figuring out was how to tell the Sun to swap on the server (on another partition). Here is
/export/root/hermon/etc/fstab which specifies this (in this case no other f/s are mounted as the root contains everything):
moriah% cat /export/root/hermon/etc/fstab moriah:/export/swap none swap sw,nfsmntpt=/swap