# systemd gone crazy : screen flashes at boot, can't log in

## Carlino

Hello,

Well, don't remember what has been upgraded last time I ran emerge -Du @world, (besides Nvidia drivers), but since, I just can't reach my box.

Boot time ends with no gdm showing up ; well I can deal with that... But the worse thing is that I can't even get to log in, from tty, since the screen, (and lights on the keyboard) keep flashing, really fast, (faster than when "kernel panic" strikes).

I hit the keys "root", intending to log as root, despite flashes, but some letters need to be hit several times to get on the screen ; just can't get my password to be validated....

So, I've chroot in, recompile kernel, but couldn't get to run module-rebuild, ending up with:

```
 Failed to validate a sane '/dev'.

bash process substitute doesn't work; this may be an indication of a broken '/dev/fd'.
```

Is it because /usr/portage is on a different fs ? Tried to mount the fs into chrooted environment, but no result.

I also mounted /var/log, so I could dig in logs and try to find out why boot is so funky...Ran journalctl from chrooted environment, but  no luck : I got "No journal files were found".

So I ended up recording the boot sequence, (it goes so fast before it switches to flashing tty, that I can't even get to read where it twisted).

So what I see (in slow motion from my cell phone recorder):

```
[ OK ] Starting Accounts Service...

[ OK ] Created slice user-104.slice.  

          Starting User Manager for UID 104

[ OK ] Started Session  c1 for user gdm.

[ OK ] Started User Manager for UID 104...

          Stopping User Manager for UID 104...

[ OK ] Stopped User Manage for UID 104.

[ OK ] Removed slice user-104.slice.

[ OK ] Created slice user-104.slice.  

          Starting User Manager for UID 104

[ OK ] Started Session  c2 for user gdm.

[ OK ] Started User Manager for UID 104...

          Stopping User Manager for UID 104...

[ OK ] Stopped User Manage for UID 104.

[ OK ] Removed slice user-104.slice.

[ OK ] Created slice user-104.slice.  

          Starting User Manager for UID 104

[ OK ] Started Session  c3 for user gdm.

[ OK ] Started User Manager for UID 104...

          Stopping User Manager for UID 104...

[ OK ] Stopped User Manage for UID 104.

[ OK ] Removed slice user-104.slice.

[ OK ] Created slice user-104.slice.  

          Starting User Manager for UID 104

[ OK ] Started Session  c4 for user gdm.

[ OK ] Started User Manager for UID 104...

          Stopping User Manager for UID 104...

[ OK ] Stopped User Manage for UID 104.

[ OK ] Removed slice user-104.slice.
```

And so on in an infinite loop with c ("from Started Session  c* for user gdm".) increasing. I thing that's what lead to the flickering / flashing tty.

So, is there a way I could boot interactively with systemd, like with OpenRC ? What did I miss with not being able to emerge --ask @module-rebuild ( Failed to validate a sane '/dev'.), after I recompile my kernel, from chroot env ? Any clue about  slice user-104.slice ?

Regards

----------

## Carlino

So far I managed to boot in rescue mode, editing grub before boot time, and adding "rescue" at the end of the line starting with "linux" ; so, I do boot and get a nice and shiny tty, (no flickering or shining behaviour).

So now, I can get to see what journalctl -r is up to.... Well, first hint, it's talking about a nvidia driver not matching the kernel version, or so. I'm going to recompile, and then run @module-rebuild. 

Let's start from here....

----------

## Carlino

Well, upgrading the kernel didn't change much besides the fact that now, boot time doesn't end up with endless loop on "Created slice user-104.slice", it just hangs on

```
[ OK ] Started User Manager for UID 104... 
```

and then, nothing ; hanged, frozen.... BUT, if I pool out RJ45 cable, then, gdm starts, and I can login... but that's it, because, I never reach the desktop environment ; black screen. even weirder : RJ45 cable pooled out, GDM available : I only can log in as root, and reach the desktop environment ! how nuts is that ?!

----------

## Wallsandfences

Did you reinstall nividia-drivers?

Rüdiger

----------

## eccerr0r

Also make sure you emerge with --newuse just in case... 

Just double checking your kernel (gentoo-sources) is built with "systemd support"?

----------

## Yamakuzure

It would be nice if systemd stopped restarting crashed services over and over again, huh? IIRC you can turn that behaviour off, but I do not remember where.

----------

