Building a kernel-only 9front ISO

In situations where PXE booting is not possible it can be useful to have an ISO file containing just the 9front kernel for booting the machine and having it continue with TLS/TCP mount of the file server.

It is assumed that file and auth servers have already been set up.

Start with a plan9.ini with parameters suitable for the target machine and network.

/tmp/plan9.ini

   cdboot=yes
   bootfile=/amd64/9pc64
   auth=192.168.1.6
   fs=192.168.1.5
   user=moody
   bootargs=tls
   #
   mouseport=ps2
   monitor=vesa
   vgasize=1024x768x16

Create a proto(2) file describing the resultant ISO file tree:

/tmp/9boottree

   uid=sys
   gid=sys
   386    d775
          9bootfat      664
          9boothyb      664
          9bootiso      664
          mbr           664
          pbs           664

   cfg    d775
          plan9.ini     664

   amd64  d775
          9pc64  664

Populate the source file tree. This could be done by copying only the needed files into a temporary directory, but it is easier to reuse the root filesystem, replacing any files that need replacing — plan9.ini in this case:

   bind /tmp/plan9.ini /root/cfg/plan9.ini

Finally, build the ISO file with disk/mk9660(8):

   disk/mk9660 -c9j \
          -B /386/9bootiso \
          -s /root -p /tmp/9boottree \
          -v 'Plan 9' kern.iso

Burn the resulting kern.iso to a suitable drive.