Upgrade to Linux 4.x
_Originally created by @intrigeri on [#10298 (Redmine)](https://public-redmine-archive.tails.boum.org/code/issues/10298)_
Tails should work on recent hardware. If we don’t do anything special,
we’re stuck with Linux 3.16, missing out on the Linux kernel’s hardware
support improvements.
Our preferred way to upgrade Tails to Linux 4.x would be to migrate from
aufs to overlayfs (tails/tails#8415). We have done a lot of the needed work on our
side, but before we go on we are blocked by work that must be done
upstream (AppArmor support for overlayfs in the Linux kernel, aka.
tails/tails#9045).
If this plan works in time for Tails 3.0 (Debian Stretch), fine: we’ll
then have to finish porting Debian Live and Tails -specific bits to
overlayfs.
If it does not, then we will have to stick to aufs, which implies
building out-of-tree aufs modules ourselves (note that the support
patches have been re-introduced in Debian’s Linux kernel, so that is
possible now.
In any case, we will also have to deal with other new issues we’ll
discover with recent kernels (see subtasks).
Feature Branch: feature/10298-linux-4.x-aufs
### Subtasks
- [x] tails/tails#9969
- [x] tails/tails#11511
### Related issues
- **Related to** tails/tails#11441
- **Related to** tails/tails#11518
- **Blocks** tails/tails#7649
- **Blocks** tails/tails#10289
- **Blocks** tails/tails#11281
- **Blocks** tails/tails#8485
issue