Re: what about netbooting anything?

[Martin Dudle <dudle@ifi.unizh.ch>]

hi markus

long time ago you answered a mail from me. busy with other things
i finally found the time to answer now.

markus@infoscape.com wrote:
> 
> Martin Dudle writes:
> 
>  > forgive me if you consider this question stupid, but what about
>  > improving the netboot toolkit for it can create images out of any
>  > kind of program?
> 
> Booting an operating system is a very tricky thing, and therefore all
> operating systems use fundamentally different approaches to doing
> this. While it would theoretically be possible to join all of the
> mknbi-* programs under one single wrapper, there will not be very much
> code that they will have in common.
> 
>  > is there anybody working on such a thing?
> 
> Not as far as I would know, but if all you worry about is having a
> single program, then it should not be very difficult to write a shell
> script that calls the correct executable.

i'm not interested in having a single program that much than rather
having a program that enables me to boot free bsd over the net.

>  > it would be nice to have a mknbi (and no mknbi-XXXXX) that can take any
>  > kind of kernel (eg. a freebsd kernel) and make it net-bootable.
> 
> I do not have a freebsd system (as a matter of fact, I do have
> anything other than NT right now anyways), but writing a version of
> mknbi-freebsd should be very simple. You can probably modify
> mknbi-linux and use "etherboot"'s loader for freebsd as a
> reference. IIRC, freebsd directly loads an ELF image file.

what would i need to build up? the biggest problem for me right now is
to know what it basically takes to load any system. where and how do
i pass the paramteres to the kernel? what different structures must be
initialized in memory? i saw that the linux loader has a block of data
where it stores the data it gets from the boot server.

>  > looking at the sources i roughly guess that the different OS's rely
>  > on certain static facts which are unique to the specific OS. i'm
>  > interested in information about those basic assumptions and structures
>  > and would appreciate if someone might point me into the right
>  > direction.
> 
> If the operating system, that you want to load, comes with source
> code, then the best bet is taking a look at the source and possibly
> also taking a look at what other loaders (e.g. LILO, or the Grub)
> do. If the operating systems do not include source code, then you will
> have to dig up some other reference. This might not always be a simple
> task. If the target operating system has not been written with
> remote-bootability in mind, then things can be very tricky --- this is
> the reason why we still cannot boot NT.
> 
> Good luck and feel free to ask specific questions,

thanks. i think i will really try to implement a mknbi-fbsd. althought
i don't clearly see the different steps i'll have to follow.

gruss,

-martin

ps: soll ich lieber auf deutsch schreiben? ich habe gesehen, dass du 
aus deutschland kommst und dort auch studiert hast. :-)