Re: Etherboot/BSD Netboot root_path tag handling

[Klaus Espenlaub <espenlaub@informatik.uni-ulm.de>]

Bob Edwards wrote:
> 
> Klaus Espenlaub wrote:
> > The Linux Terminal Server Project already ran into this but worked around
> > by using the -d switch to set the root directory name inside the nbi image.
> > However this should be just a temporary hack in my opinion.
> >
> > Any votes against a small patch to the first.S file that reverses the order
> > of things - first the DHCP/BOOTP tag, then the boot file dirname?
> >
> 
> A very democratic process! As with any democracy, the folk being asked to
> make the decision are seldom able to think through the issues and need to
> have the thinking done for them. In this case, to save me some time, can you
> please spell out the implications (positive and negative) of swapping the
> order of parsing these tags? Namely, what is going to break in existing
> setups?

I didn't mean to be democratic - I just wanted some more opinions or even someone
telling me I'm totally insane dropping a feature his life depends on :)

Anyway, I understand your point, especially because the code in question is
some x86 assembly code... 

A short summary of the current behaviour (ONLY kernel images prepared with
"mknbi-linux -d rom" are affected at all by the change - if you passed "kernel"
or some absolute path with the -d option NOTHING will change):
- the dirname of the boot file is used as the root FS source directory
- if there was no dirname (i.e. the boot file used a /tftpboot relative name),
  the option 17 value is used

My original suggestion was to swap them, but Ken suggested to drop the dirname
code altogether.  However this will break the use of mknbi-linux for boot loaders
that don't pass the BOOTP info down to the next stage loader.  Etherboot has no
problem with that, but who knows which loader does.  The comments in first.S
indicate that at least ancient versions of (BSD) netboot didn't pass anything
and some similarly ancient versions passed just the boot file name.  I'd expect
those installations to be either extinct or keep using the old versions of
mknbi-linux, so this is probably not a showstopper and Ken's suggestion is now
my favourite.

Cheers
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