As of r304321, boot loader gained support of SHA512 and Skein; setting checksum=skein should be allowed for boot filesystems. Same as https://www.illumos.org/issues/8906 . Illumos change https://github.com/illumos/illumos-gate/commit/0dd498c0020c4a0dd34d350b07f97399a475d102 should be applied on FreeBSD too.
A commit references this bug: Author: allanjude Date: Fri Jun 19 17:59:56 UTC 2020 New revision: 362396 URL: https://svnweb.freebsd.org/changeset/base/362396 Log: ZFS: Allow setting checksum=skein on boot pools PR: 245889 Reported by: delphij Sponsored by: Klara Inc. Changes: head/cddl/contrib/opensolaris/cmd/zfs/zfs.8 head/cddl/contrib/opensolaris/cmd/zpool/zpool-features.7 head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_ioctl.c
^Triage: Has this been merged to stable/11 already (mfc-stable +), or is it pending? base r362396 did't have an MFC flag, so unsure. If its already been merged, please add a "base rXXXXX" to autolink to the merge commit in a comment and set mfc-stable12 to + again, otherwise please reference this PR: in a subsequent merge and set it to + after the merge is complete
A commit references this bug: Author: allanjude Date: Sat Jul 11 15:57:48 UTC 2020 New revision: 363098 URL: https://svnweb.freebsd.org/changeset/base/363098 Log: MFC r362396 ZFS: Allow setting checksum=skein on boot pools PR: 245889 Reported by: delphij Sponsored by: Klara Inc. Event: July 2020 Bugathon Changes: _U stable/11/ stable/11/cddl/contrib/opensolaris/cmd/zfs/zfs.8 stable/11/cddl/contrib/opensolaris/cmd/zpool/zpool-features.7 stable/11/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_ioctl.c _U stable/12/ stable/12/cddl/contrib/opensolaris/cmd/zfs/zfs.8 stable/12/cddl/contrib/opensolaris/cmd/zpool/zpool-features.7 stable/12/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_ioctl.c
Sorry for noise, maybe I misunderstand… In man page of this patch (cddl/contrib/opensolaris/cmd/zfs/zfs.8) "The salted checksum algorithm is currently not supported on FreeBSD.", but in "sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_ioctl.c" if section "Salted checksums are not supported on root pools." was removed. So are salted checksums supported on FreeBSD or not? And on root/boot pools?
Skein is supported, for root/boot Edon-r is not supported at all (not even to mount the filesystem)