Hi,

I use Kubuntu 15.10 + backport + neon (http://neon.kde.org/).
I have this strange behavior on login (SDDM):

In fact, I have this after some seconds.

I found the following workaround (see video):
http://ovh.to/xCV9YuY
1- Login
2- Logout => Now SDDM is correct
3- Login again

Why this bug? What could be the solution?

Garbled framebuffer - possibly in relation with the bootsplash.
What GPU/driver is this?

Try to use a VGA terminal during the boot phase:
https://wiki.archlinux.org/index.php/GR ... ramebuffer

(Ubuntu should use /etc/default/grub as well, so don't worry about the distro)

Hi,

My graphic card is a [AMD/ATI] RS780L [Radeon 3000].

I tried to disable the "framebuffer" but I still have the same issue.
As you can see in the video:
1- sddm login panel is correct
2- after 1s, it becomes strange
3- after a blind login/logout, sddm is again correct and still correct

An idea?

Radeon or fglrx driver?
Is it a multiscreen setup?
Does switching the VT (ctrl+alt+f2) fix or prevent this?


The sddm greeter is a QtQuick application, ie. a GL canvas.
The garbage indicates that at some point some data is corrupted, eg. when transferring VBOs between system and gpu RAM.

The system log jounald?) might contain gl errors or warnings about this.
For the radeon driver, enabling DRI3 might help

luebking wrote:Radeon or fglrx driver?

Radeon

luebking wrote:Is it a multiscreen setup?

No

luebking wrote:Does switching the VT (ctrl+alt+f2) fix or prevent this?

When the screen is strange like on the screen capture, it's impossible to swith on tty2.

luebking wrote:The sddm greeter is a QtQuick application, ie. a GL canvas.
The garbage indicates that at some point some data is corrupted, eg. when transferring VBOs between system and gpu RAM.

The system log jounald?) might contain gl errors or warnings about this.

With KSystemLog, I didn't find error. How to do to find them?

luebking wrote:For the radeon driver, enabling DRI3 might help

I did it but I still have the issue:

Code: Select all

 s@ORDI> grep -i dri3 /var/log/Xorg.0.log                     
[    45.971] (**) RADEON(0): Option "DRI3"
[    46.054] (**) RADEON(0): DRI3 enabled

"journalctl", but I'm not sure whether sddm/qml logs GL errors/warnings/debug messages.
If the driver itself notices some issues, you might find them in "dmesg"

> it's impossible to swith on tty2
ie. you keep seeing that junk? (if you've a keyboard LEDs, the numlock might change, indicating the VT switch)
Sounds like a kernel issue reg. the scanout buffer then.

Can you operate the machine via ssh (to inspect the broken state, tail dmesg when booting etc. etc.)

How does it behave when restarting the sddm service? ("sudo systemctl restart sddm" - iff ubuntu uses systemd)

luebking wrote:"journalctl", but I'm not sure whether sddm/qml logs GL errors/warnings/debug messages.
If the driver itself notices some issues, you might find them in "dmesg"

Hi,

I don't really know what I have to search.
But I found this in "journalctl":

Code: Select all

mars 30 17:54:22 ORDI /usr/sbin/irqbalance[865]: WARNING: MSI interrupts found in /proc/interrupts
mars 30 17:54:22 ORDI / /usr/sbin/irqbalance[865]: But none found in sysfs, you need to update your kernel
mars 30 17:54:22 ORDI / /usr/sbin/irqbalance[865]: Until then, IRQs will be improperly classified

In "dmesg", I didn't see interesting log but I don't know how to read them.
Here is the content of "dmesg": http://pastebin.com/p09beF3j

luebking wrote:
> it's impossible to swith on tty2
ie. you keep seeing that junk? (if you've a keyboard LEDs, the numlock might change, indicating the VT switch)

Yes.

luebking wrote:Sounds like a kernel issue reg. the scanout buffer then.

Can you operate the machine via ssh (to inspect the broken state, tail dmesg when booting etc. etc.)

I don't know how to do and I have got only one computer.

luebking wrote:
How does it behave when restarting the sddm service? ("sudo systemctl restart sddm" - iff ubuntu uses systemd)

SDDM is correct when I launch "sudo systemctl restart sddm" exactly like after the blind login/logout in my video.
Only the first launch of SDDM is not correct and after 2s (see video).

Thank you for your help.