GEOM class idea...

Soeren Straarup xride at
Mon Jun 14 14:06:36 GMT 2004

On Sun, 13 Jun 2004, Poul-Henning Kamp wrote:

> OK, here is one of the more nasty ideas for a GEOM class:
> Many of us read CD's into iso images, stick them on a harddisk and
> mount them from there when we need to access them.  This usually
> costs us a md(4) vnode gadget, and that is really a waste.
> Write a GEOM class which is a slicer, but it needs to work on CD9660
> image headers as metadata, and work the following way:
> Read in the first ISO image onto our archive disk:
> 	dd if=/dev/acd0 of=/dev/ad8 bs=2k
> On close, the disk is tasted, and our "geom_cdarch" class finds a
> valid CD9660 volume description and attaches to the disk.
> It extracts the image size from the CD9660 descriptor (offset 0x8050,
> 32bitLE.  Repeated at 0x8054 as 32bitBE) and creates a slice with
> this ISO image in it.
> Since there is no valid CD9660 descriptor on the disk right after
> this image, the remaining free space gets put into a special
> slice ("ad8.freespace").
> To read in the next ISO image:
> 	dd if=/dev/acd0 of=/dev/ad8.freespace bs=2k
> On close the geom_cdarch class looks for a valid CD9660 volume and
> if it finds one, creates a new slice and recreates the freespace
> slice with the space now available, and we can repeat the process
> until we run out of space.
> Any takers ?
> --
> Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
> phk at FreeBSD.ORG         | TCP/IP since RFC 956
> FreeBSD committer       | BSD since 4.3-tahoe
> Never attribute to malice what can adequately be explained by incompetence.

Question: Will the iso 'fs' be bootable and listed by the boot manager?
That is if the iso is a bootable iso image

Best regards Søren

Soeren Straarup   | aka OZ2DAK aka Xride
FreeBSD wannabe   | FreeBSD since 2.2.6-R
     Don't let your brain be in idle to long
      it might get stuck there

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