Hi Kibi,
I see Ben Hildred send a reply before I finished this draft :-) I'll
reply to it separately.
On 10 November 2017 at 14:50, Cyril Brulebois <kibi@debian.org> wrote:
> Nicholas D Steeves <nsteeves@gmail.com> (2017-11-10):
>> 1) get a list of disks
>> 2) identify the disk used by the installer
>> 3) exclude the disk found at #2
>
> How do you do 2?
>
> Last I touched this, nothing obvious appeared in d-i to know what the
> installer was booted from. ISTR having suggested at the time that
> bootloaders could set something to help d-i figure out where it booted
> from, but I don't think anything happened in this area since then.
My first thought was to implement something like the /\ this /\ , so
that /proc/cmdline could be used. The next idea was to tie it to the
installer build somehow. eg:
/dev/disk/by-uuid/2017-10-10-10-09-57-00 for Debian 9.2.1. Is that only for amd64?
* is a link that points to a device name...remove that disk from the list
* not necessary for optical media IIRC
* how hard would it be to make the installer aware of this?
* Is PTUUID better? (eg: 5c91ec76) Or does this depend on blkid?
Alternatively, and expensive fall-back like this:
use existing code to get list of disks and partition
for i in partitions_or_unpartitioned_disks; do
mount $i \
&& check for something that indicates it's Debian installation media \
&& check for specific version of something (would need a hook when building media to embed this)
or maybe check for existence of initrd.gz in $i, unpack it \
and compare checksum of something on initrd_used_to_boot_installer and initrd_found_on_$i \
&& rm disk_for_$i from list
or alternatively, maybe just check for a file that indicates "This is Debian installation media"
done
Alternatively all disks that match something that indicates "This is
Debian installation media", unless in expert mode. This breaks
installation from one drive that has been prepared as installation
media to another drive that has been prepared as installation media
(possibly with a different version),
Most these methods break down for custom media that uses
grub-imageboot...that's the case I don't know how to solve, but maybe
the following would work: use /proc/cmdline and then loop-back mount
the image, check for match between file on running system and mounted
image, and remove the parent disk/partition from the list?
Cheers,
Nicholas
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