LinuxSA Mailing list archives

  From: Rick Marshall <rjm@herzfeld.com.au>
  To  : Mark Newton <newton@atdot.dotat.org>
  Date: Fri, 12 Mar 1999 16:35:25 +1100

Re: Big disk drive + small PC + linux

>

Mark,

Thanks for the details on Linux boot. As you probably gathered I did a lot of
support work with Unixware, SCO, and Solaris (System V Unix) in the old days. I
guess I had naively expected Linux to be at least as smart about ignoring the
BIOS as the older products. I know... never assume.

The 1023 limit is because the BIOS uses only 10 bits for cylinder address. The
other 6 are used for something else. Its sort of the BIOS equivalent of the Y2K
problem. Who could possibly need a disk with more than 1024 cylinders? or a
computer with more than 640K RAM? What was I saying about assuming things....
I think Intel made some sort of similar assumptions when designing the segmented
architecure.

Don't forget too that real Unix can sub partition a disk partition which is why
/stand can work. This would make a good holiday project. ;-)

Rick

> Rick Marshall wrote:
>
>  > Can't speak for Linux because I haven't tried it, but in the old days SCO,
>  > Interactive, and Solaris could boot any size disk irrespective of the
>  > BIOS. This is because Unix and (I presume) Linux store the disk config in
>  > the boot sector. All you should need is any BIOS def to get going. We used
>  > to use type 1 and let Unix take over from there.
>
> Linux is rather different from most other UNIXes in the way it boots.
>
>

<snip>

> Linux could benefit from that third approach: Rather than using LILO
> to boot /vmLinuz or whatever, it should be possible to write a tertiary
> bootstrap and have LILO boot that instead.  This would have the benefit
> of introducing significant extra functionality, usability and
> configurability without having any impact whatsoever on the existing
> boot-time infrastructure employed by Linux.
>
> Does anyone want to take on a holiday project? :-)
>
> In the short term, you need to make sure that the disk you're booting
> from features a boot partition which falls entirely within the first
> 1024 cylinders.
>
>     - mark
>
> --------------------------------------------------------------------
> I tried an internal modem,                    newton@atdot.dotat.org
>      but it hurt when I walked.                          Mark Newton
> ----- Voice: +61-4-1958-3414 ------------- Fax: +61-8-83034403 -----

--
mailto:rjm@herzfeld.com.au <=>  RICK MARSHALL  <=> http://www.herzfeld.com/isl
   International Software Laboratories Pty Limited - Australia, New Zealand
     Footwear: Retail Management, Point of Sale, Wholesale, Manufacturing
    (-: All in Linux :-)   (-: On the Web :-)   (-: All in UNIBASE 5GL :-)



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