dkms module is built against host kernel, when asking to build against a chroot kernel

[Dimitri John Ledkov]

I was validating https://bugs.launchpad.net/ubuntu/+source/rtl8812au/+bug/1960169 in a focal chroot on an impish host.

despite only having v5.15 kernel in a chroot, the dkms module was attempted to be built against the host kernel, which failed.

dkms modules should respect the kernel version dkms is asking the module to built against.

Setting up rtl8812au-dkms (4.3.8.12175.20140902+dfsg-0ubuntu13~20.04.4) ...
Loading new rtl8812au-4.3.8.12175.20140902+dfsg DKMS files...
It is likely that 5.13.0-40-generic belongs to a chroot's host
Building for 5.15.0-25-generic
Building initial module for 5.15.0-25-generic
ERROR: Cannot create report: [Errno 17] File exists: '/var/crash/rtl8812au-dkms.0.crash'
Error! Bad return status for module build on kernel: 5.15.0-25-generic (x86_64)
Consult /var/lib/dkms/rtl8812au/4.3.8.12175.20140902+dfsg/build/make.log for more informati
on.
dpkg: error processing package rtl8812au-dkms (--configure):
 installed rtl8812au-dkms package post-installation script subprocess returned error exit s
tatus 10
dmesg: read kernel buffer failed: Operation not permitted
                                                         Errors were encountered while proc
essing:
 rtl8812au-dkms
E: Sub-process /usr/bin/dpkg returned an error code (1)
root@normal-snake:~# cat /var/lib/dkms/rtl8812au/4.3.8.12175.20140902+dfsg/build/make.log
DKMS make.log for rtl8812au-4.3.8.12175.20140902+dfsg for kernel 5.15.0-25-generic (x86_64)
Wed Apr 27 15:22:31 UTC 2022
make ARCH=x86_64 CROSS_COMPILE= -C /lib/modules/5.13.0-40-generic/build M=/var/lib/dkms/rtl8812au/4.3.8.12175.20140902+dfsg/build modules
make[1]: *** /lib/modules/5.13.0-40-generic/build: No such file or directory. Stop.
make: *** [Makefile:1457: modules] Error 2

Note how make file is inconsistent with the dkms output.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Launchpad Janitor (janitor)]

This bug was fixed in the package rtl8812au - 4.3.8.12175.20140902+dfsg-0ubuntu21

---------------
rtl8812au (4.3.8.12175.20140902+dfsg-0ubuntu21) noble; urgency=medium

  * Fix dkms.conf to build against the requested kernel, rather than the
    host kernel. LP: #1970635

 -- Dimitri John Ledkov <email address hidden> Tue, 12 Dec 2023 13:56:39 +0000