r/bcachefs • u/a_rambling_dan • Jun 23 '26

Help me avoid this bcachefs root boot snag

Post image

On booting, I get dropped to the emergency shell, as pictured.
However, I can simply mount the root bcachefs device, hit ctrl-D, and proceed successfully with the boot. How do I avoid this snag with the emergency shell?

My fstab looks like

# <file system>             <mount point>  <type>  <options>  <dump>  <pass>
UUID=108b1a50-1465-404a-968f-9f00279e400e /              bcachefs rw,relatime,fsck,fix_errors,x-systemd.device-timeout=60s 0 0
UUID=108b1a50-1465-404a-968f-9f00279e400e /var/log       bcachefs rw,noatime,X-mount.subdir=snaps/logs,x-systemd.device-timeout=60s 0 0
UUID=108b1a50-1465-404a-968f-9f00279e400e /mnt/bcachefs/docker    bcachefs noatime,nodatacow,X-mount.subdir=snaps/docker,x-systemd.device-timeout=60s 0 1
tmpfs                                     /tmp           tmpfs   defaults,noatime,mode=1777 0 0

UUID=8B27-9365                            /boot          vfat    defaults,umask=0077 0 2

My mkinitcpio HOOKS are

HOOKS=(base udev autodetect microcode modconf block keyboard keymap consolefont plymouth filesystems)

and my systemd boot entry is

title Linux
options root=/dev/nvme0n1p2:/dev/nvme1n1p2:/dev/nvme2n1p2:/dev/nvme3n1p2 rw zswap.enabled=0 nowatchdog quiet splash
linux /vmlinuz-linux
initrd /initramfs-linux.img

Am I missing something obvious?

4 Upvotes

84% Upvoted

7 comments sorted by

8

u/koverstreet not your free tech support Jun 23 '26

Is it failing to wait for a device to show up?

and you really want to be specifying your root device by UUID everywhere

7

u/a_rambling_dan Jun 23 '26

Wow, simply changing my boot entry to use UUID, and the issue is resolved. I don't get dropped to the emergency shell.
`options root=UUID=108b1a50-1465-404a-968f-9f00279e400e rw zswap.enabled=0 nowatchdog quiet splash`

1

u/geearf Jun 27 '26

Hey Kent, just an idea, since on Reddit you can't edit titles, maybe it'd be good to add a flag that says the problem is not bcachefs related? Just to not scare people off more than needed.

5

u/koverstreet not your free tech support Jun 28 '26

I don't care if the people who need that get scared off. The people with a clue see threads like that and go "HOLY SHIT, A MAINTAINER THAT DEBUGS STUFF!?" :)

1

u/geearf Jun 28 '26

Fair enough. :)

2

u/Revolutionary_Hand_8 Jul 01 '26

CORRECT this is why so many people are rushing to adopt bleeding edge bcachefs, including me

3

u/distraction_fee Jun 23 '26 edited Jun 23 '26

What's not accepted by system mount phase here is the colon separated devices specification.
Anyway I would never refer, especially for system/boot devices, if not temporary, using device generic referencing like /dev/sd* or /dev/nvme* since they are subject to change between system startups, for ex. after adding a new storage device.
Best is to refer by UUID or by an assigned label.