Re: [Etherboot-developers] NIC file and ROM images

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

<ja...@Mc...> writes:

> Interesting thread about the multiple PCI headers in a
> bootrom.
> 
> I realize this would take alot of reworking how an
> Etherboot bootrom image is put together, but I'm thinking
> that much of the code in bootrom is common code that
> is used in all bootroms.  That is, the tftp, dhcp/bootp,
> main, and probably more.
> 
> Concatenating the bootrom images would just duplicate the
> same code over and over again.
> 
> I don't know what the ratio of unique code to common code
> is, but it seems like it is far more common code than unique.
> 
> What if you (we) could build a bootrom that knows about ALL
> pci network chipsets.
> 
> It would start with a whole bunch of 512 byte PCI headers.
> Followed by the main() and other common code,  Then, the 
> unique routines that each card needs. I don't know how big
> that is, but it seems pretty small, per chipset.
> 
> I use 29ee512 chips for the Linksys and 3Com cards, 
> I'll bet we could fit support for a lot of chipsets into 64k.
> 
> Well, it's just a random thought.

You caught the basic idea.  Especially when you notice Etherboot
only has 2 3com drivers, so all of the code is common.  The
open question is if it is technically feasible to have multiple
ROM images.

While writing this it occors to me that for a PCI expansion ROM
there is one other possibility.  If it isn't technically feasible
to have overlapping ROM images, it should be feasible to have multiple
images, with just enough code to remap the PCI rom and read out the
real ROM image.  Getting the BIOS to do all of the mapping and
selecting for us is probably a better way to go, but if a small enough
mini loader can be written I am certain we can make it work.

I'm hoping I can get someone else to volunteer for some of this.  But
if not I might be able to find a little bit of time to check this out.

Eric