ISO image size -regarding

Ian Smith smithi at
Sat Jan 9 14:04:21 UTC 2010

In freebsd-questions Digest, Vol 292, Issue 14, Message: 12
On Fri, 8 Jan 2010 16:41:24 -0800 Knight Tiger <caugar at> wrote:
 > Hi,
 > I am trying to create a custom ISO image of FreeBSD 6.4. The only
 > difference between the release ISO and this custom image is a modified
 > driver (amdsmb.ko). I did not create the new driver. I believe it was
 > backported from a later release.
 > I understand that this is not a backport of the driver  but a hack but
 > the ISO size surprises me.
 > The steps I had followed (listed below) resulted in an ISO image of
 > around 1 GB while the original ISO image is around 600 MB. The new
 > image work boots fine but I am not sure why it is huge
 > Steps:
 > // mount the release ISO
 > # mdconfig -a -t vnode -f 6.4-RELEASE-i386-disc1.iso -u 0
 > # mount_cd9660 /dev/acd0 /mnt
 > # pwd
 > /usr/home/scott
 > # mkdir custom
 > # cd custom
 > // copy iso files to custom
 > # rsync  -a /mnt .

Hi Scott,

nearly all in /rescue are hardlinks to one big executable, and there are 
also hardlinks in /bin and /sbin, hence your size difference.  rsync(1):

              Note that -a does not preserve hardlinks, because finding multi-
              ply-linked  files is expensive.  You must separately specify -H.
              Note also that for compatibility, -a currently does not  include
              --flags  (see there) to include preserving change file flags (if
              supported by the OS).

 > # scp scott at remote:/boot/kernel/amdsmb.ko boot/kernel/.
 > // wrap up in a ISO
 > # cd ..
 > #mkisofs -R -b boot/cdboot -no-emul-boot -o custom.iso custom
 > The ISO file is created successfully but is huge. I mounted it in
 > VirtualBox and boots just fine. I was able to install the OS (although
 > I have not checked the functionality of amdsmb changes yet)
 > I looked up information on creating custom ISO images but they had all
 > involved rebuilding the kernel while I am not sure if I need to do the
 > same Any leads is appreciated.

Yes, running make release might be just a tad over the top for this :)

cheers, Ian

More information about the freebsd-questions mailing list