There is a new pull request by ahesford against master on the void-packages repository

https://github.com/ahesford/void-packages zfs
https://github.com/void-linux/void-packages/pull/24242

zfs: add support for linux5.8
Backport an upstream commit to support `__vmalloc` prototype change. Also clean up the `dkms.patch` to avoid `dkms.conf.orig` artifacts from an imperfect match and more intelligently prune patches from the build tree in preparation for packing `clean.tar.gz` for DKMS.

Build and run tested on `linux5.7` and `linux5.8`. There should be no issues with older kernel versions.

@Vaelatern @ericonr @zdykstra 

A patch file from https://github.com/void-linux/void-packages/pull/24242.patch is attached