On Tue, 8 Feb 2000, Jonathan Stone wrote:

> Why not? If I recall correctly, the machines in question wouldn't
> MOP-boot later versions of Ultrix, either. Perhaps there's some
> language barrier here, but a bug is a bug.

 OK, it depends on how it was speced in the beginning.  If the
implementation disagrees with specs then it's a bug.

 However we call it, it's equally nasty, anyway...

> Yes, NetBSD kernels compile to ELF. They also compile to ECOFF, since
> that's all the bootPROMs can TFTP-boot.  ECOFF was developed by Third
> Eye and used by MipsCo for their compiler toolchain.  Ultrix, and IRIX
> up until IRIX5, used ECOFF.

 If ELF is supported than converting to ECOFF is just a matter of passing
the binary through objcopy or some other converter.  COFF was actually
quite popular before ELF got invented and is still used somewhere (DEC
OSF/1 for Alpha comes to mind).  It proved not to be well suited for
shared libraries though, so almost everyone switched to ELF now.  Ultrix
doesn't care, I know, since it doesn't support shared libraries (that is
version 4.4 I used some time ago did not, even though the supplied strip
program complained of an image being not ELF if provided a non-COFF binary
;-) ).

> Commiserations on being a Linux developer.  There's still hope
> you'll see the light someday.

 I don't know what you are writing of.  I am a low-level developer
(although I sometimes perform user-level stuff for fun) and I do not get
into any religious wars.  I do not think Linux is so much inferior than
NetBSD you have to feel sorry (there is MS-DOS out there for those looking
for inferiority).  I just happened to get familiar with Linux over years
(that's what we have at the University beside commercial Unices) and also
I think there is much more to code for PMAX for Linux then for NetBSD.  If
I were just to use the system, I'd probably choose NetBSD. 
Congratulations for getting so far, BTW! 

> Everyone suggests that the first time they hear about the ECOFF-only
> PROMs. Unfortunately, ECOFF and ELF are sufficiently different that
> objcopy format conversions aren't bootable.  The required extensions
> to make them bootable are (last I asked) too special-purpose to really
> fit well into binutils. That's why we have elf2ecoff in the NetBSD
> tree: it doesnt handle more general conversions, but it does grok the
> constraints of ELF->ECOFF and produce bootable kernels.

 No, no, no.  I meant the opposite -- to convert ECOFF to ELF images in
order to MOP-boot them (once I write the necessary support ;-) ).  As
opposed to TFTP-booting, MOP-booting is quite straightforward.  Apart from
the raw binary image (I mean pure contents of sections, i.e. no headers of
whatever kind), the ROM needs only to be supplied by the load address
(which gets prepended in the first MOP reply packet) an the entry point,
which is being sent in a separate packet after the image got transferred. 
So it's easy to support any image provided it's easy to fetch the two
addresses from the image and the image is easy to be stripped to a raw
binary (of course, you have to fill any holes between sections if the
source image is not contiguous).

 COFF (or whatever "cooked" format) support is what I find really weird
(or unfortunate), but it's probably a result of DEC developers being
unable to find a reasonable solution to get the load address and the entry
point passed through BOOTP/TFTP protocols.  So instead of inventing some
other format just for TFTP, they chose to put COFF support into ROM.  The
same applies to Alpha, BTW, which I've been using for a few years, before,
so I can't say I'm not familiar with the matter.

> It's supposed to, for machines that have slots for option cards to
> do FDDI or WAN.  Dave Boggs loaned me a couple of his WRL T-3 cards, but
> I dont know if they support netboot at all.

 Hmm, this would apply to any TURBOchannel equipped machines, as there are
such FDDI cards (which support netbooting) and also the "Digital Systems
and Options Catalog" claims there are TURBOchannel WAN cards for MIPS
systems, so they might support netbooting (shouldn't be that difficult to
check if you have such boards).  It depends on the firmware the cards have
-- the system firmware just checks for "boot" objects on option cards and
if such an object is present, it just gets executed.

-- 
+  Maciej W. Rozycki, Technical University of Gdansk, Poland   +
+--------------------------------------------------------------+
+        e-mail: macro@ds2.pg.gda.pl, PGP key available        +