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Joerg Wunsch
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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. :-)
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