Re: [Etherboot-developers] NBP Help

[Rajesh S. P. <raj...@ta...>]

Hello All,
     Thank you very much for your replies. I think this is the first mailling
list where i got proper replies.
     I am not going to develop any NBP, But will be developing PXE stack. So
wanted to know when NBP it is downloaded at 0:7C00 addr, how it goes, what it
lokks for execution. Is there any standard of flow of execution for NBP? how
does it executes and all that.

   As you mentioned, it unloads what not needed.
>NBPs can use as much PXE as they need to. The UNDI network driver is
available to NBP. So is DHCP/TFTP but
>it's normally broken; use the etherboot code.
Also you have talked about Etherboot PXE Loader which unloads all PXE stack
takes the control and executes, loads everything of its own (own stack) and
suppose that it should use driver that is already present.
    So as mentioned in the PXE specs, when NBP is downloaded it checks the
environment needed and if REQUIRED environment is not there it should return
control back to BIOS.
   Now I would like to know what is this REQUIRED environment, what exactly it

looks for to executes, From your mail, for etherboot it seems that NBP has its

own stack (DHCP, TFTP/MTFTP, etc) which it uses to download remaining things.
Is it same for all others.

Looking forward to receive replies.
Thanks in advance.
Regards
Rajesh



Peter Lister wrote:

> >      I am working on PXE. I would like to know how NBP interacts with
> > PXE? do they use PXE stack Or they are OS loaders and so they install OS
> > first and use the OS stack?
>
> Read the PXE spec.
>
> NBPs can use as much PXE as they need to (and unload what they don't
> need). The UNDI network driver is available to NBP. So is DHCP/TFTP but
> it's normally broken; use the etherboot code.
>
> Look at Etherboot's PXELOADER code in loader.S to see a minimal NBP. It
> just unloads the whole of PXE and then proceeds as if loaded from rom,
> using it's own driver. There is a placeholder compile flag to leave UNDI
> loaded for anyone interested in getting Etherboot to use it. Compare
> with pxelinux, which uses UNDI, DHCP and TFTP.
>
> I hope it's obvious that Etherboot must use either UNDI or a native
> driver, or there's no way to load the OS. :)
>
> Out of interest what are you doing with PXE? If all you need to do is
> boot Linux, Etherboot or pxelinux will do this now. Writing a new NBP
> just for fun seems pointless. Unless you have an odd idea of "fun".
>
> Adding UNDI support as an Etherboot driver would be a good NBP project
> and could form the basis of a useful open source NBP toolkit. It would
> be useful to quite a few people because it would make Etherboot via PXE
> easier to set up for sites which have many hardware types.
>
> You could also improve Etherboot's PXE support (i.e. so that Etherboot
> can provide PXE to other NBPs), maybe merging the existing the NILO code
> so that Etherboot can run any NBP. The standard of the Intel PXE code
> library (used in most vendor's NIC firmware) is - er - low. Look at
> HPA's pxelinux pages or read the syslinux list to see just how low. Even
> devoted PXE users would like better open source PXE firmware; Etherboot
> (and it's driver library) is the obvious platform and has had skeleton
> PXE support added already (which, I note, Eric B just migrated to its
> very own pxe.c). This could be chainable (a "menu module"?) from a
> "vanilla Etherboot" in turn loading a "real" NBP like NTLOADER. Or even
> be statically linked with an existing binary NBP...
>
> mknbi-pxe closedOS.pxe closedOS.nbi
>
> ...to turn it into something which can be loaded directly by Etherboot!
>
> >    Can anybody tell me links those will give me more deatiled
> > information on NBPs
>
> Intel changed the URL, but kept no placeholder; even their own URLs have
> not been updated, so you can be forgiven for not finding it...
>
> http://www.intel.com/labs/manage/wfm/wfmspecs.htm