[K12OSN] option-128 and option-129 in dhcpd.conf

[Jim McQuillan]

Rob,

option-129 is used to pass command-line arguments to the kernel during
the boot process.  This is ONLY when using Etherboot to load the kernel.

And, Etherboot will ignore option-129, unless option-128 contains the
special value of 'e4:45:74:68:00:00'.

Most of the time, you don't need to pass any special arguments to the
kernel.  But, if you have an ISA network adapter, you'll need to tell
the kernel about it, so that the proper driver module can be loaded.
So, you'll see things like:

    option option-128   e4:45:74:68:00:00;
    option option-129   "NIC=ne IO=0x300";

That will inform the kernel that you want to load the ne2000 network
driver module, and the IO address is 0x300.

Some cards, like the 3com 3c509 don't require the IO parameter.

Again, the above parameters are only used for Etherboot, and it really
doesn't matter whether you are booting from an etherboot floppy or an
etherboot bootrom.

For PCI network cards, we don't need to pass these parameters, because
the kernel+initrd can scan the PCI bus and discover the PCI card, and
then it does a lookup in a table, to see which module to load.

That's why I consider a minimum LTSP thin client to be anything with a
PCI bus.  It's just so much easier than dealing with old ISA stuff.

Jim McQuillan
jam at Ltsp.org



On Thu, 10 Feb 2005, Rob Owens wrote:

>
> What do these 2 lines do?  I've seen write-ups that say to comment them out if you're booting from a floppy, but I'd like to know what their purpose is.
>
> Thanks
>
> -Rob
>
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