David Evans wrote:

>   I'm a little confused about the current state of executable formats and
> so just want to check things out.

I should add this to the FAQ, but will be out of town for a couple of
days in a few hours.  If David Brownlee doesn't beat me to it I'll try
to remember to do it when I get back.

> a.out: The old format.  Can the bootblocks posted the other day handle
> 	   anything else?

No they can't.  There's not enough room in the current boot blocks to
fit more than one executable type loader or interpreter. a.out was the
original executable format for NetBSD/pmax.

> ECOFF: The format used by Ultrix.  Booting over the network requires a kernel
> 	   in this format.  The NetBSD bootblocks don't understand this.

The PROMs only understand ECOFF executables when netbooting.  Hopefully
soon (but probably after NetBSD 1.4) there will be a small ECOFF
"netboot" program that you load with TFTP (or mop) and then loads an ELF
(or other format) kernel.

> ELF: The new format.  Are kernels ever in this format?  Can the bootblocks
> 	 grok it?

Not yet :-)  I'm nearly finished a new two-stage bootblock where the
first stage to smart enough to load a small ELF program called /boot.
/boot is smart enough to load kernels in all three executable formats
above.

The "grand plan" is that only the "netboot" program will be ECOFF and
everything else will be ELF.  We will still ship the install kernel in
ECOFF as well so that the Ultrix bootblocks can load it for upgrading
those systems.

> The context of this is I'm trying to bring up a 3100 that seems very unstable
> under 1.3.3 but has been pretty much OK so far using the 'ssto' kernel from
> the February snapshot.  This is that same pesky 3100 that died horribly early
> with a TLB miss under 1.2* and 1.3 but ran fine under Ultrix.

I've seen a couple of messages from you on this but have no answers :-(

Simon.