Subject: Re: NetBSD improvements WAS Re: RealAudio
To: Jim Wise <>
From: Jonathan Stone <jonathan@DSG.Stanford.EDU>
List: current-users
Date: 11/03/1997 13:27:58
Jim Wise <> writes:

>On Sat, 1 Nov 1997, Jonathan Stone wrote:
>> Excuse me, but I genuinely don't understand.  What would a ``booter
>> application'' that runs under SunOS 4.1.x on a single-disk system look
>> like?  For Ultrix?  For VMS?  For HP-UX?  

>Well, how about a kernel and a ramdisk image for each of these
>architectures?  The CD liner notes would have instructions to:
>        1. Insert CD
>        2. Type (your system's boot PROM equivalent of)
>                 boot cdrom /boot/arch/sun3/netbsd

Huh? Sorry, I guess i'm too close to how things actually work to
understand what you're suggesting.

My first guess was that you're assuming considerably more smarts in
the bootPROMs than most machines actually have -- enough smarts to
interpret an iso9660 filesystem and load an arbitrary file out of it
as a bootimage, for starters.  But that's a long way from the truth:

  * The PROMS on many vaxes cannot boot CDs unless the CD has a
    bootblock (containig vax machinecode) at a fixed location,
    like the first 512 byte blocks.
    The PROMS  *certainly* can't boot Unix pathnames.

  * The PROMS on many vaxes cannot boot CDs unless the CD has a
    bootblock, containing mipsel machinecode,  at a fixed location.
    The standard bootblocks don't know how to boot  CDs.
    There may also be problems with 512-byte sectoring, but AFAIK
    that's a drive issue, not an issue with he CD itself.
  * AFAIK the PROMS on Sun3s cannot boot CDs unless they have a standard
    Sun3 bootblock. 

  * The PROMs on most 486 and many early Pentium motherboads 
    cannot boot CDs, either.

Of course, all these machines use the same location -- first 512
bytes, or first 4k or 8k -- for their lowest-level boot information.
Basically, they just read a few blocks of machinecode off the very
beginning of the disk and jump straight into it. (sun3s might read
data rather than code, but the format is fixed so that doesn't really help.)

So I still don't understand your suggestion. Is there something I'm
missing?  Where do theese ramdisk images *go*?  Are they on a separate
floppy for each architecture?  (What, 8 floppies? More? Size, cost
manufacturing time -- ugh.)

Is there a separate CD for each architecture?  (not as bad as the
floppies, but inventory costs, ordering the wrong CD, or even shipping
a 12-pack -- again, ugh.)