Re: Etherboot/BSD Netboot root_path tag handling

[Ken Yap <ken@nlc.net.au>]

>> Currently the root_path vendor tag (id 17) is basically ignored using
>> mknbi-linux.  The assembler code dealing with the root filesystem path
>> only looks at the tag if no boot file name is known - a case that will
>> never happen at least with Etherboot.  So generally you'll end up with the
>> dirname of the boot file.
>> 
>> 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 just looked at this and it looks like there are no adverse effects.
I would even say that the root-path should not fallback to the bootfile
but to some other default, or even blank in the last resort. (BTW,
this explains why when I install RH/Turbolinux/SuSE via NFS and ask for
th assignment of an IP address via DHCP/BOOTP, the installer suggests
bootfile as the directory to mount.)  The bootfile and the root-path
are separate things that have been wrongly (IMO) conflated in the
setup file. To be concrete, the bootfile is typically something like:
/tftpdir/xterminal.nb, whereas the root-path is typically something like:
server:/ltsroot/xterm. So actually making use of option 17 should not
affect TFTP loading, and allow the NFS path to be set via the DHCP/BOOTP
config file.
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