SUMMARY: bootabe CD.s

From: Douglas L. Acker (
Date: Sat Jul 10 1993 - 05:28:35 CDT

Not too much help .. I got the one answer below and someone else who
was willing to let me hire him to figure it out. I can confirm the
below since I tried dd'ing the raw device and that didnt work too

I think the answer is more political than technical as SUN Support
wasn't too positive.

> Does anyone have any information how one creates a bootable CD for

I havn't done this myself, but here are some points to consider:

The CD must have a Sun disk label on block 0. Using this label you can
partion the disk. Sun's disc labels describes the `harddisks'
geometry, too. Since CDROMs are not devided into tracks/cylinders/...,
Sun is using some fake parameters in their label:

e.g. the Soloris 2.1 installation disc:

rotations per minute: 350
# physical cylinders: 2048
alternates per cylinder: 0
interleave: 1
# data cylinders: 2048
# alternate cylinders: 0
# heads: 1
# of 512 byte sectors/track: 640

This covers 2048*640*0.5K = 640MB, each `cylinder' contains 640*0.5K =
320K. Partition sizes can be adjusted in `cylinder' increments.

Sun's installation discs contain a huge ISO9660 Filesystem in
partition 'a'. Note that ISO9660 reservers 16 2K sectors at the
beginning of the filesystem into which the CDROM's label is written.
The other partions 'b' .. 'h' contain a small root filesystem (a type
UFS fs) for each of the available kernel architectures. Each
machine's Boot Prom Monitor knows on which partition on the CD it can
find a suitable root fs for it's own kernel architecture. Basically
this information is encoded in the Monitor's 'cdrom' alias, that is
used when you issue the 'boot cdrom' command.

By using the full expanded form of the device name ('boot
/sbus/esp/sd@6,0:d'), you can boot from any partition on the cd.

The root filesystems are probably constructed like ordinary harddisk
root filesystems (using tools like newfs, installboot, ...).

If you're not booting, you can mount such a disk like an ordinary
ISO9660 disc (mount -rt hsfs /dev/sr0 /cdrom (sunos4), or mount -F
hsfs -r /dev/sr0 /cdrom (sunos5)).

I would probably try to create such a CD image on a spare 600MB
harddisk, test this 'CDROM dics' and later transfer the whole HD's
image onto a real CDROM disc.

Douglas L.Acker Western Geophysical Exploration Products
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