Bug#1088605: installation-reports: No installable kernel was found in the defined APT sources

["Thomas Schmitt" <scdbackup@gmx.net>]

Hi,

Daniel Lewart wrote:
> I did find 215 MiB of exact duplicate files.
> ...
> 24724624 Oct 30 10:07 firmware/firmware-atheros_20240909-2_all.deb
> 24724624 Oct 30 10:07 pool/non-free-firmware/f/firmware-nonfree/firmware-atheros_20240909-2_all.deb

These two most probably share their content in the ISO. So their
duplication would cost less than a kilobyte for the additional directory
record. Reason would be that both files had the same dev_t,ino_t
numbers when the ISO was created. In this case libisofs lets both
directory records point to the same content in the ISO.

You may verify this by a xorriso run:

  xorriso -indev debian-testing-amd64-netinst.iso \
          -find / -name firmware-atheros_20240909-2_all.deb \
                -exec report_lba --

When doing the equivalent with firmware-atheros*.deb in
debian-12.7.0-amd64-netinst.iso i get on stdout:

  Report layout: xt , Startlba ,   Blocks , Filesize , ISO image path
  File data lba:  0 ,    18483 ,     8217 , 16827872 , '/firmware/firmware-atheros_20230210-5_all.deb'
  File data lba:  0 ,    18483 ,     8217 , 16827872 , '/pool/non-free-firmware/f/firmware-nonfree/firmware-atheros_20230210-5_all.deb'

Decisive is that both files have the same Startlba.
(One could get the content by: dd bs=2048 skip=18483 count=8217 )


> 10024896 Dec  8 21:20 install.amd/gtk/vmlinuz
> 10024896 Dec  8 21:20 install.amd/vmlinuz
> 10024896 Dec  8 21:20 install.amd/xen/vmlinuz

I get from debian-12.7.0-amd64-netinst.iso :

  Report layout: xt , Startlba ,   Blocks , Filesize , ISO image path
  File data lba:  0 ,    94511 ,     3993 ,  8177600 , '/install.amd/gtk/vmlinuz'
  File data lba:  0 ,    94511 ,     3993 ,  8177600 , '/install.amd/vmlinuz'
  File data lba:  0 ,    94511 ,     3993 ,  8177600 , '/install.amd/xen/vmlinuz'

So these three share their content, too.

debian-12.7.0-amd64-netinst.iso has a size of 631 MiB.
The Linux kernel is not aware of shared content. When mounted as /mnt/iso
i see:

  $ du -s /mnt/iso
  766644  /mnt/iso

So there is a deduplication of about 135 MiB.


Have a nice day :)

Thomas