```
Mount devfs inside a beinstall(8) chroot
It turns out that without /dev/null beinstall is not able to complete and
instead exits with the messages similar to these:
```
--------------------------------------------------------------
>>> Installing kernel GENERIC completed on Sun Oct 25 17:47:37 CET 2020
--------------------------------------------------------------
/tmp/beinstall.JleGoP/mnt: Inspecting dirs /usr/src /usr/obj/usr/src/amd64.amd64
--- installworld ---
make[1]: "/usr/obj/usr/src/amd64.amd64/toolchain-metadata.mk" line 1: Using cached toolchain metadata from build at t480 on Sun Oct 25 15:53:28 CET 2020
make[2]: "/dev/null" line 2: Need an operator
make[2]: Fatal errors encountered -- cannot continuemake[1]: "/usr/src/Makefile.inc1" line 593: CPUTYPE global should be set with ?=.
Cleaning up ...
umount -f /tmp/beinstall.JleGoP/mnt/usr/src /tmp/beinstall.JleGoP/mnt/usr/obj/usr/src/amd64.amd64 /tmp/beinstall.JleGoP/mnt
Destroyed successfully
error: Installworld failed!
```
Upon a bit of debugging, it turns out that /dev/null inside the chroot
environment is full random bytes. Mounting a proper devfs inside the chroot
seems to be the most appropriate way to fix it.
```