Take a look at this:

C:\> docker run --rm -it --privileged ubuntu:focal
root@4c806ae5de55:/# apt-get update
root@4c806ae5de55:/# apt-get install dmsetup
root@4c806ae5de55:/# dmsetup targets
verity           v1.7.0
thin-pool        v1.22.0
thin             v1.22.0
raid             v1.15.1
crypt            v1.22.0
striped          v1.6.0
linear           v1.4.0
error            v1.5.0

Conspicuous by its absence is the snapshot target that I'm trying to use. It exists on a real Ubuntu install, but not here. How do I make it come back?

I'm running Docker Desktop on Windows, which appears to be configured to use the WSL 2 backend.

Edit: I presume, given the way Docker works, this has nothing to do with what container I'm trying to run, and everything to do with what Linux kernel WSL is using. From what I can tell, you can install multiple WSL distributions, but they all use the same Microsoft custom kernel. Presumably I would have to somehow build a whole custom kernel, or at least build dm_snapshot.ko suitable for loading into the WSL kernel. (?)


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