[ Sorry for the late reply. I'll try to answer your questions the best I can, but the interesting thing is at the end: zsh does not FTBFS anymore ]
On Sat, 12 Nov 2016, Axel Beckert wrote: > Hrm. A few questions, hopefully leading into the right direction: > > * Can you show me the output of "mount" of such an overlayfs mount > point? This is the output of "mount -l | grep schroot | grep overlay" on a machine which is currently building packages with the feature enabled: stretch-eatmydata on /run/schroot/mount/stretch-eatmydata-0ee2ec64-adef-490a-bcc5-63b44b7fcf66 type overlay (rw,relatime,lowerdir=/var/lib/schroot/union/underlay/stretch-eatmydata-0ee2ec64-adef-490a-bcc5-63b44b7fcf66,upperdir=/var/lib/schroot/union/overlay/stretch-eatmydata-0ee2ec64-adef-490a-bcc5-63b44b7fcf66/upper,workdir=/var/lib/schroot/union/overlay/stretch-eatmydata-0ee2ec64-adef-490a-bcc5-63b44b7fcf66/work) This is, however, something that the end user (me in this case) does not have to worry about. The way to enable overlayfs when using sbuild is to add a line saying "union-type=overlay" to the file which defines the chroot. As an example, here is my /etc/schroot/chroot.d/stretch-eatmydata file: [stretch-eatmydata] type=directory description=Debian stretch directory=/chroot/stretch groups=sbuild root-groups=sbuild preserve-environment=true union-type=overlay command-prefix=eatmydata I can then "schroot -c stretch-eatmydata" or tell sbuild to use "stretch-eatmydata" as the name of the chroot to be used. [ The end result is that sbuild does not bother to uninstall the build-dependencies after the build. Official autobuilders do something similar with LVM but I never had the time to do it that way ]. > * Does overlayfs support atimes? If not, this the likelyhood that this > is a duplicate of #764650 is very high. If it supports atimes only > optionally, can you enable them in your build and see if the issue > vanishes? I have no idea, sorry. Also, I would not even know how to enable it in case it was optional. As I said before, this is something which schroot handles for me automatically. > * Can you verify that this failure is deterministic, i.e. do 10 builds > and see if all of them fail in the same way? (zsh unfortunately has > a history of occassional non-deterministic and hard to debug test > suite failures or hangs, see e.g. https://bugs.debian.org/760061) This is where things get interesting :-) The failure happened always when I first detected it (so yes, it was deterministic). Today I tried again (a lot of times as well) and it always built ok. Then I tried "diff" on the build logs and found the variables required to reproduce it: Using Linux 4.7 AND sbuild with overlayfs. If you still want to reproduce this, I think it would still be possible by getting linux-image-4.7 from snapshot.debian.org, but that would be an exercise of "software archeologism". Let's just say that overlayfs was not good enough in Linux 4.7. I think this bug should be closed and maybe reassigned to linux as well with an "affects src:zsh". Thanks a lot.
