Add ZFS build extensions

[igorpecovnik]

Description

It seems its possible to build dkms kernel driver this way. Need further experimenting since headers might not be O.K.

Need to be enabled separate

Jira reference number [AR-9999]

How Has This Been Tested?

Not properly tested yet.

Checklist:

• [ ] My code follows the style guidelines of this project
• [ ] I have performed a self-review of my own code
• [ ] I have commented my code, particularly in hard-to-understand areas
• [ ] I have made corresponding changes to the documentation
• [ ] My changes generate no new warnings
• [ ] Any dependent changes have been merged and published in downstream modules

[igorpecovnik]

ZFS builds on target with the same packages, but fails to build in the chroot.

It is likely that 5.13.0-37-generic belongs to a chroot's host
Building for 5.15.31-x86
Building initial module for 5.15.31-x86
configure: error:
        *** Unable to build an empty module.

ERROR (dkms apport): kernel package linux-headers-5.15.31-x86 is not supported
Error! Bad return status for module build on kernel: 5.15.31-x86 (x86_64)
Consult /var/lib/dkms/zfs/2.1.2/build/make.log for more information.
dpkg: error processing package zfs-dkms (--configure):
 installed zfs-dkms package post-installation script subprocess returned error exit status 10
Setting up libzpool5linux (2.1.2-1ubuntu3) ...
Setting up zfsutils-linux (2.1.2-1ubuntu3) ...
modprobe: FATAL: Module zfs not found in directory /lib/modules/5.13.0-37-generic

[rpardini]

Yes. This can work (and does, in the case of x86 and nvidia driver in a separate PR), but if we're cross-compiling, this would run under qemu. And considering ZFS build is quite resource intensive, running make/gcc under qemu would be very, very slow.

I am due to investigate if there's an easy way to build dkms stuff in-tree, during the kernel compilation, but have not gotten to that point yet...

[igorpecovnik]

Stalled.