[systemd-devel] Too little information is shown when system enters emergency mode

[Frederic Crozat]

Le dimanche 21 octobre 2012 à 15:59 +0400, Andrey Borzenkov a écrit :
> This issue comes up relatively often on openSUSE forums. Users
> complaint that when system drops in emergency, there is nothing that
> would explain user why it happened or what to do. Typical situation is
> https://bugzilla.novell.com/show_bug.cgi?id=782904.
> 
> openSUSE by default is using "splash quiet" kernel parameter. So the
> first issue is, interpretation of "quite" changed in systemd. Now it
> means suppress all output of systemd services. As result we have the
> following (even without boot splash involved) when some device in
> fstab is missing:
> 
> doing fast boot
> Creating device nodes with udev
> Waiting for device /dev/root to appear:  ok
> fsck from util-linux 2.21.2
> [/sbin/fsck.ext4 (1) -- /] fsck.ext4 -a /dev/sda6
> /dev/sda6: clean, 31805/705744 files, 344231/2819584 blocks
> fsck succeeded. Mounting root device read-write.
> Mounting root /dev/root
> mount -o rw,acl,user_xattr -t ext4 /dev/root /root
> [   10.706463] piix4_smbus 0000:00:07.3: SMBus base address
> uninitialized - upgrade BIOS or use force_addr=0xaddr
> Welcome to emergency mode. Use "systemctl default" or ^D to enter default mode.
> Give root password for login:
> 
> This is literally everything that user sees on console. My first
> reaction was to add "systemctl --failed" as pre-exec to emergency.
> Unfortunately:
> 
> linux-q652:~ # systemctl --no-pager --failed
> UNIT LOAD   ACTIVE SUB JOB DESCRIPTION
> 
> LOAD   = Reflects whether the unit definition was properly loaded.
> ACTIVE = The high-level unit activation state, i.e. generalization of SUB.
> SUB    = The low-level unit activation state, values depend on unit type.
> JOB    = Pending job for the unit.
> 
> 0 units listed. Pass --all to see inactive units, too.
> 
> Everything is fine. This is understandable - we are now in different
> transaction and as far as I understand, systemctl --failed shows only
> results of currently active transaction (am I right?).
> 
> Only when "quiet" is turned off, do I really see something (again -
> assuming we do not have bootsplash ...)
> 
> Started /boot/efi                                                      [  OK  ]
> Dependency failed. Aborted start of /mnt                               [ ABORT]
> Dependency failed. Aborted start of Login Service                      [ ABORT]
> Dependency failed. Aborted start of D-Bus System Message Bus           [ ABORT]
> Welcome to emergency mode. Use "systemctl default" or ^D to enter default mode.
> 
> So right now if anything goes extremely wrong we have baffled user
> sitting before "emergency mode" prompt and not knowing what to do
> next. Is it considered a problem by someone else? Would it be feasible
> to turn off "quiet" and bootsplash immediately after any unit failed
> during system boot?

Please note the version of systemd (v44) in openSUSE doesn't have all
the needed bits to always display on the screen why dependency failed
(and you end up in emergency mode). This is fixed with systemd 195 which
should land in Factory pretty soon.

However, on a more general basis (not openSUSE specific), I think we
should add some special handly in systemd for a kernel command line
option (for instance debug or debug=1), which would "expand" into
"systemd.log_level=debug systemd.log_target=kmsg). This would be much
easier to tell users when debug is needed and we could also add an
additional menu entry in bootloader (under the "advanced settings") so
this setting would be always available, if needed.

-- 
Frederic Crozat <fcrozat at suse.com>
SUSE