RE: AoE INT13h progress

> You should ask AoE what the geometry is and then munge in the way a
BIOS
> would.  As an alternative, you could always have H=255 S=63; today
> that's really good enough for most things, since volumes < 8 GB are so
> rare.

Yep. Also, it is possible to figure out the geometry by reading the
partition table on an already partitioned disk, which I believe the
linux kernel does. With a combination of:

. AoE's geometry info
. HEADS=255, SECTORS=63, CYL=(Total Blocks) / 63 / 255
. Partition table derived

We should be able to come up with something that works for everyone.

> > Actually just thinking about it... maybe I can ask AoE what the
geometry
> > is...
> > . How to make it exist with Etherboot in a way that is actually
useful.
> >
> > The things to be done before it is truly useful are:
> > . 'write' and 'extended write' Int13 functions
> > . any other Int13 function that turns out to be required.
> > . A config menu of some sort, eg for setting the geometry and
turning
> > AoE booting on and off.
> 
> I don't think you need a menu for setting the geometry.

Agreed.

> You only need
> to turn AoE booting on and off if your AoE code is resident, but I
would
> suggest not doing that, and instead let the AoE-capable code be a
> secondary download, so that it can be updated centrally.

The beauty of AoE is that it requires no tcp/ip stack at all, just the
ability to send and receive Ethernet frames. No DHCP server or anything.
My idea is that you can put a new ((E)EP)ROM/Flash on a network card and
suddenly it becomes an AoE initiator. If you are relying on a server to
tftp code from then you might as well just use an initramfs.

The one thing in the settings that I forgot to mention is some way to
nominate which shelf & slot to boot from. This would require 3 bytes of
nv (2 for shelf, one for slot) storage. Most network cards have a serial
eeprom that stores the MAC address and some other info. Maybe there is
room in there, although (I think) Etherboot doesn't have a standard
interface for accessing it. That leaves some spare CMOS space in the
BIOS, which almost certainly isn't consistent between PC's. Maybe we can
use the bytes from the existing harddisk specification...

Thanks for the input.

James



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