Re: kernels gettin' bigger

Nick Moffitt writes:

> begin  The ASCII Floating Head of Seth David Schoen  quotation:
> > > > We found some individual machines that did not support it.  (I
> > > > can go grep in the archive, but I remember seeing one with my
> > > > own eyes.)
> > > 	Hmmm.  Do you know if this was a sub-pentium machine?
> > 
> > I remember that there was a P6 or later laptop that could not boot
> > ISOLINUX at all and could not boot 2.88 MB SYSLINUX machines.
> > 
> > Outside the US, machines with no no-emulation support are probably
> > much more common.
> 
> 	Is it possible to use ISOLINUX with a proper el-torito boot
> setup?
> 
> 	I mean, we use SYSLINUX with el-torito.  Lots of people use
> ISOLINUX with no-emulation.  The Web page
> <http://syslinux.zytor.com/iso.php> advises no-emulation, and notes
> that ISOLINUX will perform a heuristic to see if your boot volume is a
> 1.2, 1.4, 2.88, or hard-drive volume.  

In my understanding both no-emulation and emulation modes are part of
El Torito, but emulation mode is the only one implemented on all El
Torito BIOSes.  SYSLINUX always uses emulation mode and ISOLINUX
always uses no-emulation mode.

> 	Stepping back from implementation details for a moment, would
> it be possible to use an additional stage bootloader in the El-Torito
> image, allowing us to store a large kernel on the ISO itself?

There is MEMDISK, but I don't see how it wold help here.

If something like two-kernel monte worked on all systems, we could use
that (boot kernel A with only block device support, mount CD, then
boot kernel B with more extensive driver support).

I don't know if all BIOSes would let you do something like
no-emulation CD access through interrupt services.  If they do, then a
fancier bootloader like GRUB might work well.

-- 
Seth David Schoen <[email protected]> | Very frankly, I am opposed to people
     http://www.loyalty.org/~schoen/   | being programmed by others.
     http://vitanuova.loyalty.org/     |     -- Fred Rogers (1928-2003),
                                       |        464 U.S. 417, 445 (1984)