## Fixing Debian/Ubuntu UEFI boot manager with Debian/Ubuntu Live

source : [Code Bites](https://emmanuel-galindo.github.io/en/2017/04/05/fixing-debian-boot-uefi-grub/)  

Steps summary:  

- Boot Debian Live
- Verify Debian Live was loaded with UEFI
- Review devices location and current configuration
- Mount broken system (via chroot)
- Reinstall grub-efi
- Verify configuration
- Logout from chroot and reboot

### Verify Debian Live was loaded with UEFI :  

~~~
$ dmesg | grep -i efi 
~~~

~~~
$ ls -l /sys/firmware/efi | grep vars
~~~

### Mount broken system (via chroot)

Mounting another system via chroot is the usual procedure to recover broken system’s. Once the chroot comand is issues, Debian Live will treat the broken system’s “/” (root) as its own. Commands run in a chroot environment will affect the broken systems filesystems and not those of the Debian Live.  

#### My system is full ZFS

You have to add *-f* to force import because zfs think he should be on an other system.  
*-R* is to use an altroot path.  

~~~
zpool import -f -R /mnt rpool
~~~

~~~
zpool import bpool
~~~

Here system will tell you he can't mount it because /boot is in use. We don't wanted to mount it here, we will do it inside the chroot.  

~~~
zfs mount rpool/ROOT/ubuntu_myid
~~~

I'm in the case where ny zpool is encrypt !  

see : [zfs trouble encrypt zpool](zfs-trouble-live-boot-solution)

#### My system is not ZFS

Mount root partition (for example an lvm)  

~~~
# mount /dev/volumegroup/logicalvolume /mnt
~~~

Mount boot partition (F.e. in drive sda)  

~~~
# mount /dev/sda2 /mnt/boot
~~~

Mount the EFI System Partition (usually in /dev/sda1)

~~~
# mount /dev/sda1 /mnt/boot/efi
~~~

### Prepare chroot env

Mount the critical virtual filesystems with the following single command:

~~~
# for i in /dev /dev/pts /proc /sys /run; do sudo mount -B $i /mnt$i; done
~~~
   
Mount all zfs file system on rpool.   
   
~~~
# zfs mount -a
~~~
   
Chroot to your normal (and broken) system device

~~~
# chroot /mnt
~~~

Then here mon bpool zfs vol.  

~~~
inside chroot # zfs mount -a
~~~

Mount your EFI partition:  

~~~
inside chroot # mount -a
~~~

You should see :  

* all your rpool zfs vol
* /boot from your bpool.  
* Your efi partition.  

~~~
inside chroot # df -h
Sys. de fichiers                                 Taille Utilisé Dispo Uti% Monté sur
udev                                                16G       0   16G   0% /dev
tmpfs                                              3,2G    1,8M  3,2G   1% /run
rpool/ROOT/ubuntu_19k4ww                           272G    3,7G  269G   2% /
bpool/BOOT/ubuntu_19k4ww                           1,2G    270M  929M  23% /boot
rpool/USERDATA/nomad_43xnpb                        280G     12G  269G   5% /home/nomad
rpool/USERDATA/root_43xnpb                         269G    640K  269G   1% /root
rpool/ROOT/ubuntu_19k4ww/srv                       269G    128K  269G   1% /srv
rpool/ROOT/ubuntu_19k4ww/var/lib                   269G     34M  269G   1% /var/lib
rpool/ROOT/ubuntu_19k4ww/var/log                   269G     47M  269G   1% /var/log
rpool/ROOT/ubuntu_19k4ww/var/spool                 269G    128K  269G   1% /var/spool
/dev/nvme0n1p1                                     511M     16M  496M   4% /boot/efi
rpool/ROOT/ubuntu_19k4ww/var/games                 269G    128K  269G   1% /var/games
rpool/ROOT/ubuntu_19k4ww/var/snap                  269G    128K  269G   1% /var/snap
rpool/ROOT/ubuntu_19k4ww/var/mail                  269G    128K  269G   1% /var/mail
rpool/ROOT/ubuntu_19k4ww/usr/local                 269G    256K  269G   1% /usr/local
rpool/ROOT/ubuntu_19k4ww/var/www                   269G    128K  269G   1% /var/www
rpool/ROOT/ubuntu_19k4ww/var/lib/AccountsService   269G    128K  269G   1% /var/lib/AccountsService
rpool/ROOT/ubuntu_19k4ww/var/lib/NetworkManager    269G    256K  269G   1% /var/lib/NetworkManager
rpool/ROOT/ubuntu_19k4ww/var/lib/apt               269G     77M  269G   1% /var/lib/apt
rpool/ROOT/ubuntu_19k4ww/var/lib/dpkg              269G     41M  269G   1% /var/lib/dpkg
/dev/nvme0n1p1                                     511M     16M  496M   4% /boot/efi
~~~

### Reinstall grub-efi

~~~
inside chroot # apt-get install --reinstall grub-efi
~~~

~~~
inside chroot # grub-install /dev/sda
~~~

~~~
inside chroot # update-grub
~~~