Re: BTRFS partitioning scheme (was BTRFS with RAID1 cannot boot when removing drive)

[Saint Germain <saintger@gmail.com>]

On Thu, 13 Feb 2014 10:43:08 -0700, Chris Murphy
<lists@colorremedies.com> wrote :
> >>> sda3 = 1 TiB root partition (BTRFS), mounted on /
> >>> sda4 = 6 GiB swap partition
> >>> (that way I should be able to be compatible with both CSM or UEFI)
> >>> 
> >>> B) normal Debian installation on sdas, activate the CSM on the
> >>> motherboard and reboot.
> >>> 
> >>> C) apt-get install grub-efi-amd64 and grub-install /dev/sda
> >>> 
> >>> And the problems begin:
> >>> 1) grub-install doesn't give any error but using the --debug I
> >>> can see that it is not using EFI.
> >>> 2) Ok I force with grub-install --target=x86_64-efi
> >>> --efi-directory=/boot/efi --bootloader-id=grub --recheck --debug
> >>> /dev/sda
> >>> 3) This time something is generated in /boot/efi:
> >>> /boot/efi/EFI/grub/grubx64.efi
> >>> 4) Copy the file /boot/efi/EFI/grub/grubx64.efi to
> >>> /boot/efi/EFI/boot/bootx64.efi
> >> 
> >> 
> >>                ^^^^ is EFI/boot/ correct here?
> >> 
> >> If you're lucky then your BIOS will tell what path it will try to
> >> read for the boot code. For me that is /EFI/debian/grubx64.efi.
> >> 
> > 
> > I followed the advices here (first result on Google with "grub uefi
> > debian"): http://tanguy.ortolo.eu/blog/article51/debian-efi
> > 
> >>> 5) Reboot and disable the CSM on the motherboard
> >>> 6) No boot possible, I always go directly to the UEFI-BIOS
> >>> 
> >>> I am currently stuck there. I read a lot of conflicting advises
> >>> which doesn't work:
> >>>   - use "modprobe efivars" and efibootmgr: not possible because I
> >>> have not booted in EFI (chicken-egg problem)
> >> 
> >> 
> >> Not exactly. Boot in EFI mode into your favourite installer rescue
> >> mode, then chroot into the target filesystem and run efibootmgr
> >> there.
> >> 
> > 
> > In the end I managed to do it like this:
> > 1) Make a USB stick with FAT32 partition
> > 2) Install grub on it with:
> > grub-install --target=x86_64-efi --efi-directory=/media/usb0
> > --removable 3) Note on a paper the grub commands to start the
> > kernel in /boot/grub/grub.cfg 3) Reboot, Disable CSM in the
> > motherboard boot utility (BIOS?), Reboot with the USB stick
> > connected 4) Normally it should have started on the USB stick grub
> > command-line 5) Enter the necessary command to start the kernel (if
> > you have some problem with video mode, use "insmod efi_gop")
> > 6) Normally your operating system should start normally
> > 7) Check that efibootmgr is installed and working (normally efivars
> > should be loaded in the modules already)
> > 8) grub-install --efi-directory=/boot/efi --recheck --debug
> > (with the debug info you should see that it is using grub-efi and
> > not grub-pc) 9) efibootmgr -c -d /dev/sda -p 2 -w -L "Debian
> > (GRUB)" -l '\EFI\Debian\grubx64.efi'
> > (replace -p 2 with yout correct ESP partition number)
> > 10) Reboot and enjoy !
> 
> OK at least with GRUB 2.00 I never have to use any options with
> grub-install when installing to a chrooted system. It also even
> writes the proper entry into NVRAM for me, I don't have to use
> efibootmgr.

Yes you are right, this is probably unnecessary (see below).

> 
> Also I've never had single \ work with efibootmgr from shell. I have
> to use \\. Try typing efibootmgr -v to see the actual entry you
> created and whether it has the \ in the path.
> 

Here is the output:
BootCurrent: 0001
Timeout: 1 seconds
BootOrder: 0001,0000
Boot0000* debian        HD(2,7d8,106430,5d012c09-b70d-4225-ae18-9831f997c493)File(\EFI\debian\grubx64.efi)
Boot0001* Debian (GRUB) HD(2,7d8,106430,5d012c09-b70d-4225-ae18-9831f997c493)File(\EFI\Debian\grubx64.efi)

Ah the joy of FAT32 and the case sensitivity !
So it seems that grub-install automatically install the correct entry
 and using efibootmgr was unnecessary.
However it seems that single '\' works.

> But one thing that explains why the UEFI bootloading stuff is
> confusing for you is that every distro keeps their own grub patches.
> So there is very possibly a lot of difference between the downstream
> grub behaviors, and upstream.
> 

Understood. That is why I took the step to describe what I did.
Perhaps it will be useful for others (most info on the topic was
not for Debian...).

Thanks again for your insights !