Re: net install CD
Hi Thomas,
Thank you for the clearly defined steps on reducing the size of the
ISO. However I didn't have a working Linux system to perform those
steps with.
I ended up just putting the iso I had onto a 16GB USB stick to get my
computer working again.
I just thought I'd let you know I appreciated the effort in guiding me
through shrinking the image myself, it was very well written and
clear.
Tim McConnell
On Mon, Sep 22, 2025 at 2:15 AM Thomas Schmitt <scdbackup@gmx.net> wrote:
>
> Hi,
>
> Tim MCCONNEL wrote:
> > I got the image from: cdimage.debian.org/Debian-cd/current/amd64/iso-cd
>
> Downloading
> http://cdimage.debian.org/debian-cd/current/amd64/iso-cd/debian-13.1.0-amd64-netinst.iso
> yields a downloaded file with 821,035,008 bytes = ~0.8 GB.
>
> Thus my first proposal is to just try putting it on your 8 GB stick
> and to see what happens.
>
>
> But for the sake of science let's assume that you really have problems
> with an oversized Debian ISO.
>
> In this case i would try to repack it while removing a few files, of
> which i believe that i won't need them. The obvious candidates in the
> netinst ISO are the firmware files. In larger Debian ISOs there may be
> some other big .deb files which you may decide not to need.
>
> Mount the ISO
>
> mkdir /mnt/iso
>
> mount debian-13.1.0-amd64-netinst.iso /mnt/iso
>
> Look for big firmwware files which your hardware will not need.
>
> find /mnt/iso -exec ls -ld '{}' ';' 2>&1 | less
>
> yields lines like
>
> -r--r--r-- 2 root root 29474828 Apr 24 22:47 /mnt/iso/firmware/firmware-atheros_20250410-2_all.deb
> ...
> -r--r--r-- 2 root root 39481748 Apr 24 22:47 /mnt/iso/firmware/firmware-nvidia-graphics_20250410-2_all.deb
>
> That's 70 MB. It might be difficult to find another 130 MB of unneeded
> stuff in the 800 MB of netinst.
>
> The firmware files in ISO directory
> /firmware/
> are hardlinked with files in the
> /pool/non-free-firmware/*/firmware-nonfree/
> directories. In case of the above two:
>
> -r--r--r-- 2 root root 29474828 Apr 24 22:47 /mnt/iso/pool/non-free-firmware/f/firmware-nonfree/firmware-atheros_20250410-2_all.deb
> -r--r--r-- 2 root root 39481748 Apr 24 22:47 /mnt/iso/pool/non-free-firmware/f/firmware-nonfree/firmware-nvidia-graphics_20250410-2_all.deb
>
> You'd need to remove both file paths of each file in order to get rid
> of their content in the ISO.
>
> After having made the decision which files to remove, you may create
> the new ISO filsystem according to
> https://wiki.debian.org/RepackBootableISO#In_xorriso_load_ISO_tree_and_write_modified_new_ISO
>
> That would be:
>
> umount /mnt/iso
>
> xorriso \
> -indev debian-13.1.0-amd64-netinst.iso \
> -outdev debian-13.1.0-amd64-custom.iso \
> -rm /firmware/firmware-atheros_20250410-2_all.deb \
> /firmware/firmware-nvidia-graphics_20250410-2_all.deb \
> /pool/non-free-firmware/f/firmware-nonfree/firmware-atheros_20250410-2_all.deb \
> /pool/non-free-firmware/f/firmware-nonfree/firmware-nvidia-graphics_20250410-2_all.deb \
> -- \
> -boot_image any replay \
> -compliance no_emul_toc \
> -padding included
>
> This xorriso run is supposed to report
> -----------------------------------------------------------------------
> ...
> Drive current: -indev 'debian-13.1.0-amd64-netinst.iso'
> Media current: stdio file, overwriteable
> Media status : is written , is appendable
> Boot record : El Torito , MBR isohybrid cyl-align-on GPT APM
> Media summary: 1 session, 400896 data blocks, 783m data, 340g free
> Volume id : 'Debian 13.1.0 amd64 n'
> ...
> Drive current: -outdev 'debian-13.1.0-amd64-custom.iso'
> ...
> Removed from ISO image: file '/firmware/firmware-atheros_20250410-2_all.deb'
> Removed from ISO image: file '/firmware/firmware-nvidia-graphics_20250410-2_all.deb'
> Removed from ISO image: file '/pool/non-free-firmware/f/firmware-nonfree/firmware-atheros_20250410-2_all.deb'
> Removed from ISO image: file '/pool/non-free-firmware/f/firmware-nonfree/firmware-nvidia-graphics_20250410-2_all.deb'
> xorriso : WARNING : -volid text problematic as automatic mount point name
> xorriso : WARNING : -volid text does not comply to ISO 9660 / ECMA 119 rules
> xorriso : NOTE : Replayed 22 boot related commands
> ...
> Written to medium : 367104 sectors at LBA 0
> Writing to 'debian-13.1.0-amd64-custom.iso' completed successfully.
> -----------------------------------------------------------------------
> So the file debian-13.1.0-amd64-custom.iso is about 33000 sectors of
> 2048 bytes smaller than the original ISO.
>
> (The warning about the -volid text is due to blanks, dot, and lower
> case letters in the Volume Id text "Debian 13.1.0 amd64 n".)
>
> Inspection by
> x=debian-13.1.0-amd64-netinst.iso
> xorriso -indev $x -report_el_torito plain -report_system_area plain
> and
> x=debian-13.1.0-amd64-custom.iso
> xorriso -indev $x -report_el_torito plain -report_system_area plain
> shows the same (quite entangled) boot equipment in both ISOs.
>
> The remaining question is, whether the debian-installer tolerates the
> missing of the two firmware files. One will have to try.
>
>
> I wrote:
> > > i'm chiming in because your mail address is not subscribed to this
> > > list (you could do at https://lists.debian.org/debian-cd ) and because
> > > the two answers so far did not Cc your mail address.
>
> Tim MCCONNEL wrote:
> > Sorry if I broke the rules.
>
> No rules were broken. It's just unusual on the Debian lists to Cc
> the original poster of a mail thread. So i felt the need to justify my
> Cc to you.
> Debian mailing lists add a header X-Spam-Status where the word
> LDOSUBSCRIBER indicates that the sender is subscribed to the list.
> When i don't see it, i assume that the sender will not receive messages
> which are sent only to the list.
>
>
> Have a nice day :)
>
> Thomas
>
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