ubuntu 16.04 install fails at grub install on btrfs

[AurelienG]

root@ubuntu:/# parted -l
Model: ATA WDC WD5000BPKX-2 (scsi)
Disk /dev/sdb: 500GB
Sector size (logical/physical): 512B/4096B
Partition Table: gpt
Disk Flags:
Number Start End Size File system Name Flags
 1 105MB 1153MB 1049MB btrfs
 2 1153MB 11.6GB 10.5GB btrfs
 3 11.6GB 116GB 105GB btrfs

root@ubuntu:/# mount
/dev/sdb2 on /yourmom type btrfs (rw,relatime,space_cache,subvolid=5,subvol=/)
/dev/sdb1 on /yourmom/boot type btrfs (rw,relatime,space_cache,subvolid=5,subvol=/)

root@ubuntu:/# grub-install --root-directory=/yourmom /dev/sdb
Installing for i386-pc platform.
grub-install: warning: this GPT partition label contains no BIOS Boot Partition; embedding won't be possible.
grub-install: error: filesystem `btrfs' doesn't support blocklists.

The 1000M partition is for /boot, the 10G for /, the 100G for /home.
I created the partitions using gparted 0.25.0
The release of Ubuntu is 16.04
I expected grub-install to succeed as there is plenty of space before the first partition.

ubuntu@ubuntu:~$ apt-cache policy grub2-common
grub2-common:
  Installed: 2.02~beta2-36ubuntu3
  Candidate: 2.02~beta2-36ubuntu3
  Version table:
 *** 2.02~beta2-36ubuntu3 500
        500 http://archive.ubuntu.com/ubuntu xenial/main amd64 Packages
        100 /var/lib/dpkg/status

I got the install working by using an msdos table and an unformatted primary partition instead of free space at the beginning of the disk :

(parted) print all
Model: ATA WDC WD5000BPKX-2 (scsi)
Disk /dev/sdb: 500GB
Sector size (logical/physical): 512B/4096B
Partition Table: msdos
Disk Flags:
Number Start End Size Type File system Flags
 1 10.5MB 115MB 105MB primary boot
 2 115MB 500GB 500GB extended
 5 116MB 1165MB 1049MB logical btrfs
 6 1166MB 11.7GB 10.5GB logical btrfs
 7 11.7GB 117GB 105GB logical btrfs

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: ubiquity 2.21.63 [modified: lib/partman/automatically_partition/question]
ProcVersionSignature: Ubuntu 4.4.0-21.37-generic 4.4.6
Uname: Linux 4.4.0-21-generic x86_64
ApportVersion: 2.20.1-0ubuntu2
Architecture: amd64
CasperVersion: 1.376
Date: Mon May 9 07:28:51 2016
InstallCmdLine: file=/cdrom/preseed/ubuntu.seed boot=casper initrd=/casper/initrd.lz quiet splash ---
LiveMediaBuild: Ubuntu 16.04 LTS "Xenial Xerus" - Release amd64 (20160420.1)
ProcEnviron:
 LANGUAGE=fr_CA.UTF-8
 PATH=(custom, no user)
 LANG=fr_CA.UTF-8
 SHELL=/bin/bash
SourcePackage: grub-installer
UpgradeStatus: No upgrade log present (probably fresh install)

[Phillip Susi (psusi)]

Your disk is partitioned using GPT but you are booting in bios mode. You must create a 1 mb bios_grub partition to do this.

[AurelienG (aurelien-gelbart)]

Thanks, and sorry (ubiquity took me there instead of the forums).