RE: Etherboot as backend of INT13h AoE driver

Some more thinking, after looking at the code and development
documentation (which btw, is far and above any other open source
documentation I've ever read!)...

I'm not sure I like the sound of the pxe thing, but that could just be
because I don't really understand it.

The boot process would now look much the same up until the int19h
routine starts executing. Then, instead of doing the current etherboot
thing, it would:
. Prompt the user for a setup screen (eg which AoE device to call C:
etc) (don't know where to store this info though... probably only need a
handful of bytes of BIOS nv storage)
. Exit if we aren't set as bootable (or maybe not bother with this)
. Install our Int13h handler (can this be done from 32 bit?)
. Read the boot sector and run it as per normal boot (do we have to do
this, or can we just exit from the int19h or jump into the previous
int19h handler?)

The Int13 handler will obviously need the trampoline thing going on. I
think the only commands required are read and write sectors, although we
may need to implement the extended versions of those commands too.

From what I've read so far, we'll only need a small handful of ATA
commands, and the AoE protocol is pretty straight forward. We already
have the send and receive packet routines from the Ethernet drivers. No
need to worry about TCP/IP. No need for interrupts either. Reading or
writing is really just a matter of sending a few packets and waiting for
responses.

I'll keep looking.

James



> -----Original Message-----
> From: Marty Connor [mailto:[email protected]]
> Sent: Monday, 5 December 2005 22:48
> To: Etherboot Developers List
> Subject: Re: [Etherboot-developers] Etherboot as backend of INT13h AoE
> driver
> 
> 
> On Dec 3, 2005, at 11:35 PM, James Harper wrote:
> > Thinking about what it would take to write a BIOS driver for the AoE
> > (ATA over Ethernet) protocol, it occurred to me that Etherboot
already
> > contains the code to read and write frames from a large variety of
> > different network cards, and that it might work as the backend of
> > an AoE
> > INT13h driver.
> 
> This sounds like an interesting idea.  I've thought more than once
> that having an AOE driver for Etherboot would be very cool.
> 
> Linux Journal has a nice article on the technology here:
> 
>      http://www.linuxjournal.com/article/8149
> 
> > For this to work, Etherboot would need to be able to receive
> > interrupts
> > from the card (eg not be polled), and would need to able to stay
> > resident in high memory until another OS took over.
> 
> This sounds like something we could do with our PXE support.  I'm
> guessing that AOE code could be a protocol:
> 
>     aoe://xxxx/foo.bin
> 
> or something like that.
> 
> We have interrupt support in a number of drivers, and more can be
> added.  PXE requires INT support for UNDI, I believe.
> 
> > I think it might
> > also need to be 16 bit code too... is Etherboot 16 bit, or is it
only
> > the init code which runs as 16 bit?
> 
> I'll defer to Michael on this, but I believe we already have to deal
> with this at startup, and he has added trampoline code to deal with
> 16 bit code sections.
> 
> > Thanks
> > James
> 
> Thanks for suggesting this.  I think it would be an interesting
> addition to Etherboot.
> 
> If it's something you're interested in helping with, let us know.
> I'm sure others will have some thoughts.
> How would you like to proceed?  I think sample hardware is
> inexpensive, and I believe there is GPL-compatible code out support
AOE.
> 
> Please let us know what you have in mind in terms of development.
> 
> Marty
> 
> --
>      Try: http://rom-o-matic.net/ to make Etherboot images instantly.
> 
>     Name: Marty Connor
> US Mail: Entity Cyber, Inc.; P.O. Box 391827;
>           Cambridge, MA 02139; USA
>    Voice: (617) 491-6935; Fax: (617) 491-7046
>    Email: [email protected]
>      Web: http://www.etherboot.org/
> 
> 



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