Arch Linux

lmello

Member

From: Brazil

Registered: 2012-11-06

Posts: 300

GDM and Xorg 1.16 - Help regarding a bug report

Hello,

Since the big xorg upgrade, a functionality of GDM is quite buggy, to the point of rendering it useless - switching users.

https://www.archlinux.org/news/xorg-ser … available/

When I try to switch users while keeping my section active, I can switch to a different user, but when I log out, the GDM screen is blank and I can not even switch to another VT to restart gdm as root.

I know that this must have something to do with:

"X is now rootless with the help of systemd-logind, this also means that it must be launched from the same virtual terminal as was used to log in, redirecting stderr also breaks rootless login. The old root execution behavior can be restored through the Xorg.wrap config file (man xorg.wrap). Please note that launching X through a login-manager (gdm, kdm, ...) doesn't yet provide rootless access."

The problem may reside, however, on the inter drive I'm using:

"The xf86-video-intel package doesn't provide dri3 support anymore because of multiple rendering bugs."

Anybody else with the same problem? If so, please help me to report a bug where it 'belongs', because I'm not certain if it's gdm that must be recompiled/upgraded, or if it's the X server or my graphic card's driver...

I have installed:

xorg-server 1.16.0-6
xorg-server-common 1.16.0-6
xorg-server-devel 1.16.0-6
xorg-server-xdmx 1.16.0-6
xorg-server-xephyr 1.16.0-6
xorg-server-xnest 1.16.0-6
xorg-server-xvfb 1.16.0-6
xorg-server-xwayland 1.16.0-6

xf86-video-intel 2.99.914-4

gdm 3.12.2-1

Last edited by lmello (2014-08-06 19:39:01)

---

Fundamental Axiom of the Universe (aka Murphy's Law): Whatever can go wrong, will go wrong.
First Digital Deduction: Nothing obeys Murphy's Law so well as computers.
Second Digital Deduction: Everything go wrong at least once.
Third Digital Deduction: Things go wrong even when there's absolutely no possibility of anything go wrong.

ulke

Member

Registered: 2011-04-29

Posts: 50

Re: GDM and Xorg 1.16 - Help regarding a bug report

EDIT: While user switching works for me with the config file below (it didn't work without it), logging out a user while another is logged in still produces the same black screen, no VT switching behavior. Bummer.

Same here, also with Gnome Shell, GDM, and Intel graphics.

After reading man xorg.wrap I made a file /etc/X11/Xwrapper.config with the following contents:

needs_root_rights=yes
allowed_users=anybody

Now it works as it used to.

Last edited by ulke (2014-08-08 08:18:21)

lmello

Member

From: Brazil

Registered: 2012-11-06

Posts: 300

Re: GDM and Xorg 1.16 - Help regarding a bug report

EDIT: While user switching works for me with the config file below (it didn't work without it), logging out a user while another is logged in still produces the same black screen, no VT switching behavior. Bummer.

Same here, also with Gnome Shell, GDM, and Intel graphics.

After reading man xorg.wrap I made a file /etc/X11/Xwrapper.config with the following contents:

needs_root_rights=yes
allowed_users=anybody

Now it works as it used to.

THANKS ulke! I created this file with this contents and It's working now.

Should we write this down in the Arch Wiki? Where?

---

Fundamental Axiom of the Universe (aka Murphy's Law): Whatever can go wrong, will go wrong.
First Digital Deduction: Nothing obeys Murphy's Law so well as computers.
Second Digital Deduction: Everything go wrong at least once.
Third Digital Deduction: Things go wrong even when there's absolutely no possibility of anything go wrong.

ulke

Member

Registered: 2011-04-29

Posts: 50

Re: GDM and Xorg 1.16 - Help regarding a bug report

THANKS ulke! I created this file with this contents and It's working now.

Should we write this down in the Arch Wiki? Where?

Does logging out a user while another is logged in also work? It doesn't for me. Also, I'm not quite sure what the file actually does, so I'd be hesitant to put this in the Wiki.

V1del

Forum Moderator

Registered: 2012-10-16

Posts: 25,435

Re: GDM and Xorg 1.16 - Help regarding a bug report

This already is mentioned in the news announcement quoted here, note in particular

X is now rootless with the help of systemd-logind, this also means that it must be launched from the same virtual terminal as was used to log in, redirecting stderr also breaks rootless login. The old root execution behavior can be restored through the Xorg.wrap config file (man xorg.wrap). Please note that launching X through a login-manager (gdm, kdm, ...) doesn't yet provide rootless access

so I don't think it has to specifically mentioned in a wiki entry Maybe it should be clarified somehow that you HAVE to create a config because of the lack of support in DMs, but to me this announcement was pretty clear in that regard so I wouldn't know a better choice of words

ulke

Member

Registered: 2011-04-29

Posts: 50

Re: GDM and Xorg 1.16 - Help regarding a bug report

V1del, I read this announcement, but did not anticipate that it meant that Gnome's user switching would break. On the contrary I took the sentence you highlighted to mean that if X is started through GDM, nothing changes.

V1del

Forum Moderator

Registered: 2012-10-16

Posts: 25,435

Re: GDM and Xorg 1.16 - Help regarding a bug report

It implies that you have to switch to the old root method as logind based user logins wouldn't work, I'm more suprised that it apparently worked for initial login instead of already dying there

lmello

Member

From: Brazil

Registered: 2012-11-06

Posts: 300

Re: GDM and Xorg 1.16 - Help regarding a bug report

THANKS ulke! I created this file with this contents and It's working now.

Should we write this down in the Arch Wiki? Where?

Does logging out a user while another is logged in also work? It doesn't for me. Also, I'm not quite sure what the file actually does, so I'd be hesitant to put this in the Wiki.

It works for me... I put a *might* in this section https://wiki.archlinux.org/index.php/GDM#Xorg_1.16. Feel free to exclude it if you want.

V1del, I read this announcement, but did not anticipate that it meant that Gnome's user switching would break. On the contrary I took the sentence you highlighted to mean that if X is started through GDM, nothing changes.

It implies that you have to switch to the old root method as logind based user logins wouldn't work, I'm more suprised that it apparently worked for initial login instead of already dying there

So it's GDM and other login managers that ought to be modified upstream in order to be functional with rootless login from Xorg 1.16?

---

Fundamental Axiom of the Universe (aka Murphy's Law): Whatever can go wrong, will go wrong.
First Digital Deduction: Nothing obeys Murphy's Law so well as computers.
Second Digital Deduction: Everything go wrong at least once.
Third Digital Deduction: Things go wrong even when there's absolutely no possibility of anything go wrong.