On Mon, Nov 13, 2017 at 10:35:19AM -0700, Ben Hildred wrote: > On Fri, Nov 10, 2017 at 12:50 PM, Cyril Brulebois <[1]kibi@debian.org> > wrote: > > Nicholas D Steeves <[2]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. > > OK, This Is a crazy Idea, but . . . When generating Installer images, they > get various readmes and so on, and I believe one of them includes version > information, so we can parse that file for the version number, compare it > with the one in the initrd (to be added). This handles the common cases of > cd (overkill as cds are read only) and USB (presumably most important), > but fails on net-install (where it is not needed). We can have installer > loader scripts copy the version info file to mark the drives they are > using which should catch most of the rest of the cases. > A variation of this is to have a pseudo random token in the version file > which is passed on the command-line to the installer instead of modifying > the initrd. This has the advantage that we could have special case values > for net-boot to skip the scan. (ie if the token was a hexadecimal value > but the special case was the word netboot. > > both cases make identifying and protecting partitions used to store > archives and iso images easy by manually placing the version file. Why does net-boot need to be special cased? By default, shouldn't the net-boot media be excluded as an installation target--except for the expert case. Another feature that could be piggybacked on the "mount block device and identify if it's Debian installation media" is OS identification. It's been so many years since I dual-booted with another OS that I don't know if this functionality already exists. If it does exist, I'm guessing that is where this new "Identify installation media" could be added. Re: the identification step: I don't think it's crazy :-) Do you know if such a magic file already exists (especially if the installer build was recorded)? Can busybox-provided cat, grep, cksum and cmp provide strong enough magic file match, or do you think we also need a /sys/.../something/uuid check as well? Cheers, Nicholas
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