Hi Ludo, On Sun, 17 Nov 2019 at 22:15, Ludovic Courtès wrote: > The only thing that’s missing here is that currently “guix build > /gnu/store/….drv” fails if the .drv doesn’t already exist, which is why > the trick above resorts to a lower-level mechanism. I miss how to fetch this missing .drv. :-) For example this evaluation built a recent enough Guix, right? --8<---------------cut here---------------start------------->8--- $ wget -q -O - 'http://ci.guix.gnu.org/build/1943556' | jq '."derivation"' --8<---------------cut here---------------start------------->8--- outputs the derivation file. But how do you fetch it? I have not found in the Cuirass API doc. Maybe I missing the obvious. Then, once I have downloaded this derivation, the old Guix should be able to build it, right? No daemon issue? --8<---------------cut here---------------start------------->8--- $ guix build "/gnu/store/bz1qqy225p1jlicwf07iiqr79icqddcv-guix-4de11dda7.drv" --8<---------------cut here---------------start------------->8--- This will populate the store with a new guix. Then I need to pull as root, in order to also update the daemon, right? --8<---------------cut here---------------start------------->8--- # /gnu/store/-guix-4de11dda7/bin/guix pulll --8<---------------cut here---------------start------------->8--- > Perhaps ‘guix pull’ should have a ‘--rescue’ option to do the trick > above? Is it possible? We need to track on Cuirass one recent enough derivation of Guix for each architecture, right? All the best, simon