Re: [Etherboot-developers] Q: Multiple drivers.

[<ebi...@ln...>]

ke...@us... (Ken Yap) writes:

> >1) Is it reasonable for etherboot to support multiple cards,
> >   and possible multiple cards with different drivers at
> >   one time.
> 
> Yes, this is a reasonable thing. In the past when the code was in a ROM,
> it would have violated the principle of least surprise for the code on
> one NIC's ROM to boot another NIC, but Etherboot has extended its
> tentacles into the BIOS and other places now. 

Hmm. Then it isn't intentional that etherboot always boots the first
NIC of that type in the system?

As for BIOS's I guess it should be documented that when you have a
relationship with the motherboard vendor, and a motherboard has an
onboard NIC it is a reasonable request to ask the vendor to the
motherboard vendor to include the option rom in their BIOS.

> One thing that would be
> nice, if possible, is for the single driver version to by selection or
> by default boot only the physical NIC it lives in. That way controlling
> the interface is a matter of choosing the right NIC to put the ROM in.

That sounds like a totally reasonable choice.
 
> The interface to the drivers is rather poor, it only takes the first NIC
> it finds. Ideally it should enumerate all the NICs it can boot and
> choose a good default or give the user a choice (one of multiple NICs of
> the same or different models).

A workable strategy is to try each NIC in turn and when that fails
try the next NIC, with ESC selecting the next NIC.  It isn't perfect
but it does a fairly good job.  Starting with the NIC we are associated
with can certainly help.

Trying multiple NIC in parallel is faster, but it is harder to implement.

> >2) Would it be reasonable to have a version of the hard/floppy
> >   booting code that uses polled ide/floppy drivers instead of
> >   the BIOS.
> 
> Provided that this is a compile time option, this is ok. I expect that
> the code will take up room and ROM users should not have to pay the cost
> in ROM space if they are not using the disk access. At the same time,
> the API to disk access could probably be improved.

That isn't a hard provision to meet.
 
> >I have code that implements supports multiple cards with the same
> >drive, and polled ide & floppy access, and I'm trying to find
> >the best place for it to have a home, be maintained, and be useful.
> >
> >If it something you don't mind seeing in etherboot then I will look
> >into this.  
> 
> Sounds great. Any contributions are gratefully received.

Cool.

What got me started is Adam Agnew who assembled the polled ide code is
working on trusted booting.  And intially wrote the code against
etherboot.


Eric