v4l2loopback-dkms won't build on kernel 5.8

[Jonas Gamao]

I'm on HWE-edge kernels (5.8.0-25-generic as of right now), and v4l2loopback won't build on KDE Neon 20.04.

Here's the output when I run `# apt full-upgrade`:

  Setting up v4l2loopback-dkms (0.12.3-1ubuntu0.1) ...
  Removing old v4l2loopback-0.12.3 DKMS files...

  ------------------------------
  Deleting module version: 0.12.3
  completely from the DKMS tree.
  ------------------------------
  Done.
  Loading new v4l2loopback-0.12.3 DKMS files...
  Building for 5.8.0-25-generic
  Building initial module for 5.8.0-25-generic
  ERROR (dkms apport): kernel package linux-headers-5.8.0-25-generic is not supported
  Error! Bad return status for module build on kernel: 5.8.0-25-generic (x86_64)
  Consult /var/lib/dkms/v4l2loopback/0.12.3/build/make.log for more information.
  dpkg: error processing package v4l2loopback-dkms (--configure):
   installed v4l2loopback-dkms package post-installation script subprocess returned error exit status 10

Any idea what's the issue?

[Jonas Gamao (yamiyukisenpai)]

This is the contents of make.log:

DKMS make.log for v4l2loopback-0.12.3 for kernel 5.8.0-25-generic (x86_64)
Mon 09 Nov 2020 01:23:16 PM EST
Building v4l2-loopback driver...
make -C /lib/modules/5.8.0-25-generic/build M=/var/lib/dkms/v4l2loopback/0.12.3/build modules
make[1]: Entering directory '/usr/src/linux-headers-5.8.0-25-generic'
  CC [M] /var/lib/dkms/v4l2loopback/0.12.3/build/v4l2loopback.o
/var/lib/dkms/v4l2loopback/0.12.3/build/v4l2loopback.c:137:47: warning: ‘struct timeval’ declared inside parameter list will not be visible outside of this definition or declaration
  137 | static inline void v4l2l_get_timestamp(struct timeval *tv) {
      | ^~~~~~~
/var/lib/dkms/v4l2loopback/0.12.3/build/v4l2loopback.c: In function ‘v4l2l_get_timestamp’:
/var/lib/dkms/v4l2loopback/0.12.3/build/v4l2loopback.c:147:4: error: dereferencing pointer to incomplete type ‘struct timeval’
  147 | tv->tv_sec = (time_t)ts.tv_sec;
      | ^~
/var/lib/dkms/v4l2loopback/0.12.3/build/v4l2loopback.c:147:16: error: ‘time_t’ undeclared (first use in this function); did you mean ‘ktime_t’?
  147 | tv->tv_sec = (time_t)ts.tv_sec;
      | ^~~~~~
      | ktime_t
/var/lib/dkms/v4l2loopback/0.12.3/build/v4l2loopback.c:147:16: note: each undeclared identifier is reported only once for each function it appears in
/var/lib/dkms/v4l2loopback/0.12.3/build/v4l2loopback.c:147:23: error: expected ‘;’ before ‘ts’
  147 | tv->tv_sec = (time_t)ts.tv_sec;
      | ^~
      | ;
/var/lib/dkms/v4l2loopback/0.12.3/build/v4l2loopback.c: In function ‘vidioc_qbuf’:
/var/lib/dkms/v4l2loopback/0.12.3/build/v4l2loopback.c:1527:24: error: passing argument 1 of ‘v4l2l_get_timestamp’ from incompatible pointer type [-Werror=incompatible-pointer-types]
 1527 | v4l2l_get_timestamp(&b->buffer.timestamp);
      | ^~~~~~~~~~~~~~~~~~~~
      | |
      | struct __kernel_v4l2_timeval *
/var/lib/dkms/v4l2loopback/0.12.3/build/v4l2loopback.c:137:56: note: expected ‘struct timeval *’ but argument is of type ‘struct __kernel_v4l2_timeval *’
  137 | static inline void v4l2l_get_timestamp(struct timeval *tv) {
      | ~~~~~~~~~~~~~~~~^~
/var/lib/dkms/v4l2loopback/0.12.3/build/v4l2loopback.c: In function ‘v4l2_loopback_write’:
/var/lib/dkms/v4l2loopback/0.12.3/build/v4l2loopback.c:1954:22: error: passing argument 1 of ‘v4l2l_get_timestamp’ from incompatible pointer type [-Werror=incompatible-pointer-types]
 1954 | v4l2l_get_timestamp(&b->timestamp);
      | ^~~~~~~~~~~~~
      | |
      | struct __kernel_v4l2_timeval *
/var/lib/dkms/v4l2loopback/0.12.3/build/v4l2loopback.c:137:56: note: expected ‘struct timeval *’ but argument is of type ‘struct __kernel_v4l2_timeval *’
  137 | static inline void v4l2l_get_timestamp(struct timeval *tv) {
      | ~~~~~~~~~~~~~~~~^~
/var/lib/dkms/v4l2loopback/0.12.3/build/v4l2loopback.c: In function ‘init_buffers’:
/var/lib/dkms/v4l2loopback/0.12...

[Launchpad Janitor (janitor)]

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