[Gb-ccb] Backup of the CCB microdrive

[Martin Shepherd]

On Fri, 14 Oct 2005, John Ford wrote:
>...
> Maybe we could network boot it?

I've spent this afternoon looking into this possibility. The GRUB
boot-loader has the capability to boot over the network, although
setting this up would take some work. It would involve the following
steps:

1. The version of GRUB that comes with Fedora doesn't enable network
    booting. Thus I would need to recompile and reinstall grub. I
    downloaded the source code this afternoon, and verified that it has
    a network driver and corresponding configuration option that should
    support the network interface on the CCB computer. Basically I
    would do the following, in the directory of the GRUB source-code
    distribution:

      ./configure --enable-natsemi
      make
      make install
      grub-install

    I don't want to do this unless we agree that we want to go ahead
    with network booting, because if there is any problem with the
    installation of grub, then the system could become unbootable.

2. We would need to make the kernel etc available on an NRAO computer,
    via TFTP. This brings up 3 questions:

     A. Would NRAO's security policy allow this?
     B. Can one make a mounted CD (ie a live CD like Knoppix) available
        via TFTP, or would we have to copy the contents of the CD to a
        TFTP area first?
     C. Do live CDs like Knoppix contain the normal kernel files etc, or
        do they have some custom compression/decompression scheme that would
        flummox GRUB?

3. To actually start a network boot, without having to take the lid
    off the CCB to connect a monitor and keyboard, we would need access
    to the GRUB boot screen, via the serial COM port.

    I have been investigating this as well. The most convenient method
    would have been to get the BIOS to redirect all console output to
    the COM port. Some BIOSes do support this, but I just got a reply
    to my query about this to Lippert, and they told me that the BIOS
    on the Cool Roadrunner III CPU-board, doesn't support console
    redirection. They told me that it might be possible to add this,
    but that if we wanted this, then we should talk to their sales
    department. ie. It would cost more money.

    Since the BIOS can't do console redirection, we won't be able to
    interact with the BIOS screens from the COM port, and will have to
    take the lid off the CCB if we ever want to fiddle with the BIOS.

    However, the lack of console redirection doesn't prevent us from
    redirecting console messages to the COM port, once the boot-loader
    has taken over control from the BIOS. This can be done by adding
    configuration lines like the following to the
    GRUB configuration file (/etc/grub.conf):

     serial --unit=0 --speed=9600 --word=8 --parity=no --stop=1
     terminal --timeout=10 serial console

    We will need to hook up a VT100-compatible terminal emulator,
    configured as above, to check that this works.

    If a terminal emulator that isn't VT100 compatible, is used, then
    we would instead have to use:

     serial --unit=0 --speed=9600 --word=8 --parity=no --stop=1
     terminal --timeout=10 --dumb serial console

    I'm putting off trying this until somebody has time to hook up a
    terminal emulator to the COM port on the front panel of the CCB.

4. I would add a menu entry to the Grub configuration file, to allow
    the selection of the network boot. This would look something like:

     Title Network Boot
     # Get an IP address for the CCB computer.
     dhcp
     # Assuming that the DHCP server doesn't tell us the TFTP server's address,
     # we then need to explicitly specify this.
     tftpserver 192.33.116.whatever
     # Tell GRUB that the root-directory is to be accessed over the
     # network device.
     root (nd)
     # Tell Grub the name of the kernel image on the TFTP server, and
     # tell the kernel not to use DMA with the microdrive, or ACPI.
     kernel /vmlinuz-2.6.12-1.1398_FC4 ro root=LABEL=/ ide=nodma acpi=off
     initrd /initrd-2.6.12-1.1398_FC4.img

So. Is it worth setting up network booting, and when would it be
possible to try out the console-redirection to the COM port, with a
terminal emulator?

Martin