Mobian issue

content/blog/2023-01-mobian-black-screen.md

@@ -0,0 +1,90 @@
+---
+Title: Black screen at boot on my PinePhone
+Date: 2023-01-13 09:33:00
+Summary: My phone was no longer booting…
+---
+
+OK so today my [PinePhone](https://fr.wikipedia.org/wiki/PinePhone)
+does no longer boot, it goes like this:
+
+- Press power button to boot it,
+- type rootfs passphrase (I use full disk encryption),
+- Mobian "spash screen" for a short time,
+- black screen, and that's it.
+
+My first bet was a graphical issue due to a recent upgrade ("sweet"
+memories of Ubuntu failing to start its X server after almost any
+upgrade...) so I try to ssh to it first... "no route to host", damned!
+It don't have its IP yet so it failed before network setup.
+
+But it's a PinePhone, and it runs
+[Mobian](https://mobian-project.org/), a Debian for mobiles, so I'm
+not in the dark, let's read the boot logs first before going down the
+rabbit hole of connecting a UART on the jack port to debug it over
+serial:
+
+- Press power button,
+- type rootfs passphrase again,
+- press a volume button to get rid of the Mobian splash to see logs
+
+```text
+The root filesystem on /dev/mapper/calamares_crypt requires a manual fsck
+```
+
+OK!
+
+Looks easy, but without a keyboard? Let's mount the
+[eMMC](https://en.wikipedia.org/wiki/MultiMediaCard#eMMC) over USB!
+
+As my phone boots using [Tow-Boot](https://tow-boot.org/) it's easy:
+
+- Shut it down (~8s on the power button).
+- Plug it to laptop with a USB-C cable.
+- Make it enter "USB Mass Storage mode" (by holding the
+  volume up button at startup before and during the second
+  vibration).
+- Instantly my laptop sees it and udisks auto mounts it, gnome asks
+  for main partition passphrase to mount it too, nice!
+- Boom, it disappears... and on `journalctl -e` I see `usb 1-5: device
+  descriptor read/64, error -71` ... `I/O error, dev sda` ...
+
+At this point I think there's just two options: either my USB-C cable
+was badly plugged, or my eMMC is dead. I vote for the USB-C cable
+issue and try again.
+
+- Rebooting phone in USB mass storage mode again, but this time
+  without giving my passphrase to avoid automount: it
+  needs an fsck anyway.
+- I can browse `/media/mdk/boot` and see no read error in `sudo journalctl -f`.
+- `sudo fdisk -l /dev/sda` sees ~30GiB and both partitions.
+
+
+I use encryption so to fsck the root partition, I have to use `cryptsetup` first:
+
+```bash
+$ sudo cryptsetup open /dev/sda2 mobian  # it asks for my passphrase
+$ file /dev/mapper/mobian  # That's the unencrypted view of my partition
+/dev/mapper/mobian: symbolic link to ../dm-0
+$ sudo fdisk -l /dev/mapper/mobian  # Just out of curiosity
+Disk /dev/mapper/mobian : 28.47 GiB, 30574379008 octets, 59715584 secteurs
+$ sudo fsck /dev/mapper/mobian  # Running fsck manually!
+fsck from util-linux 2.38.1
+e2fsck 1.46.6-rc1 (12-Sep-2022)
+root contains a file system with errors, check forced.
+[many many errors]
+$ sudo mount /dev/mapper/mobian /mnt  # To check if it works
+$ ls /mnt  # Yeah!
+bin  boot  dev  etc  home  lib  lost+found  media  mnt  opt  proc  root  run  sbin  srv  sys  tmp  usr  var
+$ sudo umount /mnt
+$ sudo cryptsetup close mobian
+```
+
+It looks OK, let's reboot the phone...
+
+It works!!!
+
+I know, your grandma would not be able to do fix it that way (mine
+neither), but I'm still very happy to be able to fix my phone myself
+when it has issues.
+
+What would people do when a phone does no longer boot? Buy another?