Ben's notes

Fedora - reinstall / fix grub2 UEFI

Some hints to fix booting your favourite OS. Tested with Fedora 25 and Windows 10.

Fedora

Boot from live USB

Switch to root and mount the needed filesystems:

sudo -i

mkdir -p /mnt/sysimage
mount /dev/fedora/root /mnt/sysimage

mount --bind /dev /mnt/sysimage/dev
mount --bind /run /mnt/sysimage/run
mount -t devpts pts /mnt/sysimage/dev/pts
mount -t proc proc /mnt/sysimage/proc
mount -t sysfs sys /mnt/sysimage/sys 

modprobe efivarfs
mount -t efivarfs efivarfs /mnt/sysimage/sys/firmware/efi/efivars

Copy the resolv.conf to have some networking in the chroot:

mkdir -p /mnt/sysimage/var/run/NetworkManager
cp /var/run/NetworkManager/resolv.conf /mnt/sysimage/var/run/NetworkManager

Enter the chroot and mount /boot and /boot/efi filesystems:
```
chroot /mnt/sysimage

mount /boot
mount /boot/efi
```

Reinstall grub2:

dnf -y reinstall grub2 grub2-efi grub2-efi-modules shim
grub2-mkconfig -o /boot/efi/EFI/fedora/grub.cfg

Check if entry exists in EFI menu:
```
efibootmgr
```

Add entry if it is missing:

grep efibootmgr /var/log/anaconda/program.log 
22:47:35,458 INFO program: Running... efibootmgr
22:47:35,477 INFO program: Running... efibootmgr -c -w -L Fedora -d /dev/nvme0n1 -p 2 -l \EFI\fedora\shim.efi

#Run the command found above:
efibootmgr -c -w -L Fedora -d /dev/nvme0n1 -p 2 -l '\EFI\fedora\shim.efi'

(optional) Add another OS for example:

efibootmgr -c -w -L Windows -d /dev/nvme0n1 -p 2 -l '\EFI\Microsoft\Boot\bootmgfw.efi'

(optional) Change the boot order:
```
efibootmgr -o 1,0
```
(optional) Delete entry:
```
efibootmgr -b 0 -B
```
(optional) Change timeout:
```
efibootmgr -t 2
```

Unmount filesystems and reboot:

umount /boot/efi
umount /boot
exit
umount /mnt/sysimage/sys/firmware/efi/efivars
umount /mnt/sysimage/sys
umount /mnt/sysimage/run
umount /mnt/sysimage/proc
umount /mnt/sysimage/dev/pts
umount /mnt/sysimage/dev
umount /mnt/sysimage

reboot

Windows 10

Modify the path for the Windows boot manager to Fedora:
```
bcdedit /set {bootmgr} path \EFI\fedora\shim.efi
```
Alternatively you can use EasyUEFI to edit the entries.