Commit Graph

2 Commits

Author SHA1 Message Date
Peter Wemm
c3aac50f28 $Id$ -> $FreeBSD$ 1999-08-28 01:08:13 +00:00
Joerg Wunsch
c38b4f3b91 (Part #2, after the Internet link broke totally yesterday.)
This is the long-threatened ISO 9660 CD-ROM bootstrap code.

This work has been sponsored by Plutotech International, Inc (who paid
the initial work), and interface business GmbH (where i did most of
the work).  A big thanks also goes to Bruce Evans, for his continuing
help and answering my stupid questions.

The code is basically functioning, with the following caveats:

. Rock Ridge attributes are not yet supported.
. Only SCSI CD-ROMs are supported, since i fail to see any possibility
  to determine the drive type using BIOS functions.  (Even for hard disks,
  this determination is done by a big hack only.)
. El Torito specifies a lot of crap and useless misfeatures, but crucial
  things like the ability to figure out the CD TOC have been ``forgotten''.
  Thus, if you wanna boot a multisession CD, you need to know at which CD
  block your session starts, and need to speciffy it using the @ clause.

. None of the CD-ROM controllers i've seen so far implements the full
  El Torito specification at all.  Adaptec is probably the closest, but
  they miss on non-emulation booting (which would be the most logical
  choice for us).  Thus, the current code bloats the 7.5 KB boot code
  up to 1.44 MB, in order to fake a `floppy' image.

  If you wanna use it, specify this file as the boot image on the
  command-line of the mksiosfs command (option -b).

  Caveat emptor: some versions of the Adaptec BIOS might even fail to
  access the CD-ROM at all, using the BIOS functions.  I think i've
  notice this for ver 1.26, the code has been tested with ver 1.23.

The boot string is as follows:

        [@sess-start] [filename] [-flags]

sess-start      Extend # where the last session starts, measured in
                CD-ROM blocks.

filename        As usual, but the input is case-insensitive by now
                (since we  don't grok RR anyway).

flags           As usual, but -C (use CDROM root f/s) is default, so
                specifying -C will decactivate this option (which is
                probably not what you want :).

A lot of cleanup work is probably required, and some of the files
could/should be merged back to biosboot, perhaps made conditional on
some #ifdef.  The malloc implementation that comes with cdboot might
also be useful for kzipboot.  (I needed a malloc() since the root dir
ain't fixed in size on a CD.)

I've been testing all this with a 2.2-STABLE as the base for biosboot.
I don't expect too many surprises, although i know the biosboot stuff
has been changed a lot in -current lately.  I'm sure Bruce will
comment on all this here anyway. :-)
1997-07-11 05:52:41 +00:00