I am working on making d-i support installs from USB storage. Booting is
dealt with, but there's still the question of how d-i finds the install
media to install additional udebs and/or to get debs from.
As I thought about this, I realized that once it's mounted, a USB
storage device is essentially just another hard drive, so the design
should also allow for installs where a generic hard drive is used as the
install media. I am also leaning toward getting this to work with any
iso image that has d-i on it, so I don't have to worry about creating my
own isos (or other media) too.
The four scenarios I am envisioning are:
1. Download a debian iso to a partition you will not be putting Debian on.
"Boot" via a batch file that runs linux. May only work on more
antique versions of DOS.
2. Same as #1 except create a floppy image and boot from it.
3. Put a debian iso on a USB storage device, and boot from it[0].
4. Boot from a floppy which then detects your USB storage device.
In all cases the d-i initrd that is loaded contains drivers for hard
disks and usb storage, as well as a udeb (provisionally called
hd-media-detect) that tries to mount each hard drive and partition in
turn, and looks for iso files on them[1]. Once the d-i iso is found, it
loop mounts it to /cdrom, and the rest of the install proceeds more or
less as normal, using the cdrom-retreiver to pull files from it,
possibly using a modified version of cdrom-checker to validate it first.
The only caveat during the install is that it will need to avoid letting
the user partition the drive from which the iso is loop mounted, or
format the partition the iso is in. This may call for some changes in
the partitioner and formating modules.
Before reboot, for scenario 2, there should probably be something to
unmount the iso and remind the user that they can unplug their usb
device now, equivilant to the cd eject code in cdrom-detect.
--
see shy jo
[0] I dunno if a straight iso dd'd to usb storage is bootable. This may
really involve putting the iso in a partition on the usb device,
along with a d-i initrd and kernel, and adding a proper boot loader.
[1] This would be a two stage scan. In the first stage, just look for
*.iso, *.raw[2] in the top level directory. If a d-i iso is not found,
go on to the second stage, which runs find on the whole drive. User
interaction may or may not be involved, to choose amoung isos.
[2] If we keep shipping confusingly named ".raw" files.
Attachment:
signature.asc
Description: Digital signature