Re: [Etherboot-developers] NBP Help

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

"Rajesh Shantaram Patharkar" <raj...@ta...> writes:

> 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.

Almost by definition there is no standard flow. 

But since you are limited to 32KB, generally the next step is to download
a kernel.

If you want to look at the open source implmentations there is:
etherboot,
syslinux,
and a few others.

> 
>    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.
> 

Etherboot is probably unique in that regard.  As the usuall use for etherboot
is not being loaded from a boot rom but instead being the boot rom
and loading other programs.  Etherboots success is a direct reflection
of what a poor job PXE has done in developing a useable standard.

Eric