Re: grub booting from cdrom/dvd ?

[Gerard W. Patterson]

On Thu, Dec 13, 2001 at 08:27:12PM +0100, Arno Wilhelm wrote:
> 
> Sounds great. It seems that it solves my questions above partially. In this 
> way you can boot an OS on a harddisk from the bootable cdrom. 
> But is it also possible to boot an OS from the bootable cdrom as it where a 
> harddisk? I doubt that because I could not find a way in the device section 
> of the info manual to name a cdrom device on the grub-promt. I found the 
> names for the harddisk or floppy ( hd0,0) or (fd0) ) but no name for a cdrom. 
> The only way I could imagine that if could work is the possibility of grub to 
> pass it a bios drive number ( e.g.: 0x80 for hd(0) ) instead the name of a 
> device. Maybe this could be the solution ? Does anybody know the bios drive 
> number of the first cdrom ?
> 

Hmm,

  Well this is what I use this for:

  I have a small linux operating system on my CD.  I use it to install a
  larger image for a install set that I have been designing for work.
  
  The way it works, is to boot a kernel from the eltorito image. (it is just
  a boot disk with a small initial ramdisk in it) which then mounts the
  CDROM and copies the rest of the operating system to some ramdisks and
  carries on from there.  This way I get a RAM based linux system that I can
  use to install/rescue/recover the main system on the hard drives of the
  system.

  I think this procedure could be extended to use the CDROM as a read-only
  /usr partition to provide a much larger operating system but I just liked
  the flexability of everything completely in RAM so I could put other
  things in the CDROM drive.  However, I usually work with systems with a
  minimum of 256 MB - 512 MB of ram too.  

  I don't know for sure, but it seems that you shouldn't have to worry about
  a BIOS drive number for the CDROM--if you use the above system.  However,
  you might be able to trick the machine in thinking your CRROM is a
  harddrive by setting the 'treat removable disks as hard drives option' in
  your BIOS.  I know there is this option for adaptec SCSI chipsets, but not
  sure about others.

  Regards,

    Gerry
-- 
Gerard W. Patterson, B.Sc           |   Computalog Ltd.
Software Engineering                |   Edmonton, AB
<address@hidden>    |   Canada