Re: cdrom boot for sgi
On Tue, Apr 23, 2002 at 01:53:16PM +0200, Florian Lohoff wrote:
> > The install system seems to start normally
> >
> > Also I have noticed that the fake volheader has "number of heads" set to zero... can use fdisk to
> > interogate this... A SGI boot CD has number of heads set to one.
>
> That should be fixed easily - But this shows there is something wrong
> with reading 512 byte blocks from a cdrom - I think we get low-level
> (Read: scsi) errors when trying to issue a scsi read request on non 2048
> byte aligned boundaries or something. One would need an scsi bus analyzer
> to actually get more reasonable knowledge of what going on.
I've been following this thread with a little interest, since I was a
CD mastering engineer by day for a lot of years.
I just want to confirm that you know that what's on the media for
CD/CD-R/CD-RW isn't even stored in a tracks/sectors scheme. It's
written in one long serial groove that runs from the inner part of the
disc to the outer part of the disc, like an LP record in reverse. So
the software is not for the CD drives benefit -- it couldn't care less
about byte boundaries _internally_. It just has to make things look
right at the guzotta.
Reading 512-byte blocks is strictly a hardware function, should have
nothing to do with the cd writer. I presume people are trying to read
from SCSI CD-ROM drives that they already know will boot the machine
in question? (I know it's a stupid question, just checking the obvious.)
I do remember having to go hunt down old Toshiba T-3401's in order to
get things working on some Indy's, DECstations, and MicroVAXen I
salvaged. Anything over 4x maybe, 8x (almost certainly) is unlikely
to work.
Pardon the bandwidth if I've missed the point, either partially or
entirely.
Cheers,
Phil Mendelsohn
--
www.rephil.org
"Trying to do something with your life is like
sitting down to eat a moose." --Douglas Wood
--
To UNSUBSCRIBE, email to debian-mips-request@lists.debian.org
with a subject of "unsubscribe". Trouble? Contact listmaster@lists.debian.org
Reply to: