Debian ISOs on USB stick, was: SOLVED

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

Hi,

David Christensen wrote:
> > the Debian installer modifies the contents of the USB flash drive when
> > it runs.

Do you mean inside the range of the ISO image or outside by creating a
new partition ?


songbird wrote:
> if it is an iso image copied to the USB stick it should not
> be modified if you haven't somehow told the installer to
> install the system to that USB stick (somehow).

There are other parties which feel entitled to operate on the EFI System
Partition of a USB stick.
In
  https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1056998
we found that Lenovo Thinkpad firmware created directories for storing
an empty file named "/efi/Lenovo/BIOS/SelfHealing.fd" and that MS-Windows
created a 12-byte file named "/System Volume Information/WPSettings.dat"
when it had contact with the USB stick.


> i guess if you wanted to be really sure you could mount it read-only.

I think it's the installer which mounts the ISO 9660 filesystem.
Whatever, the Linux kernel has no regular means to alter an ISO 9660
filesystem. Neither kernel nor Debain installer will be so daring to
operate with byte level commands on that filesystem.

But the FAT filesystem in file /boot/grub/efi.img of the ISO 9660
filesystem in debian-12.*-amd64-netinst.iso is advertised by the partition
table of the image and thus attracts vermin.


Have a nice day :)

Thomas