Other Display Manager

What is your prefered display manager?

  • xdm - X.Org display manager

    Votes: 13 24.5%
  • slim - SLiM desktop independent graphical login manager

    Votes: 4 7.5%
  • lighdm - Lightdm lightweight cross-desktop display manager

    Votes: 13 24.5%
  • sddm - QML based X11 and Wayland display manager

    Votes: 7 13.2%
  • gdm - GNOME 2.0 version of the xdm display manager

    Votes: 2 3.8%
  • pcdm - QT5 based display manager

    Votes: 0 0.0%
  • wdm - WINGs display manager

    Votes: 0 0.0%
  • ly - TUI ncurses-like display manager

    Votes: 3 5.7%
  • login as text and use startx

    Votes: 20 37.7%

  • Total voters
    53

astyle

Daemon

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Per this post straight from the Forums:
You can log in from command line, even if you have a DM running :p
 

sidetone

Daemon

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That's the point of a login manager. [to require a password]

Alternatively, autologin may work fine too. Perhaps depending on purpose, and if the PC has a single login only for public use.

Does a password only protect from physical PC access, or does it help with online vulnerabilities too? I thought it was both.
 

astyle

Daemon

Reaction score: 634
Messages: 1,438

That's the point of a login manager.

Also, why on earth are these called "display manager"? As I understand them, they are more of a login manager.
yeah, a misnomer that somehow stuck. I'm guessing that this is because the greeter actually launches Xorg after the user logs in. Not the easiest-to-understand logic, but that's how Xorg actually works.
 

kpedersen

Son of Beastie

Reaction score: 2,153
Messages: 3,001

jb_fvwm2

Daemon

Reaction score: 208
Messages: 1,841

On a bsd derivative that used lightdm as one of its install options, its login processes eventually after updates broke and I reverted to the startx method above, vs a reinstall [ after hours trying to find a fix... ]
 

jbodenmann

Well-Known Member

Reaction score: 234
Messages: 447

yeah, a misnomer that somehow stuck. I'm guessing that this is because the greeter actually launches Xorg after the user logs in. Not the easiest-to-understand logic, but that's how Xorg actually works.
Which types of interfaces does a login manager actually use? Surely it can't use X for rendering. Does it use the kernel framebuffer (at least that is a thing in Linux)? I take it that keyboard & mouse inputs can be grabbed through devd/evdev?

I'm not doubting that it works, I'd just like to understand how it works :)
If you can just point me to some documentation that's fine too.
 

grahamperrin

Son of Beastie

Reaction score: 822
Messages: 2,647

… switching to an alternative desktop: Why would one use more than one desktop?

The two reasons given by bsduck.

Another: simple curiosity. When I switched operating systems (<https://forums.freebsd.org/posts/535014> point 9) I was amazed by the discovery that more than one desktop environment could be installed; that (without conflict) a second DE could be used without removing the first.

… "display manager"? As I understand them, they are more of a login manager. …

Probably a colloquial abbreviation of X display manager.


Historically (1989), X11R4 set new standards that included the X Display Manager Control Protocol (XDMCP) … and so on.

… autologin implies using no password. …

Authentication is required when using System Settings in KDE Plasma to set automatic log in behaviour for SDDM:

1634008343125.png1634008407599.png1634008487603.png

Regarding autologin without a display manager: Here's a post by wblock@ on how to do it: https://forums.freebsd.org/threads/trouble-calling-startx-in-start-up-script.22304/#post-125992

I don't understand the code, sorry. Can it allow a system administrator to configure the system to automatically start a desktop environment session with my ID without my passphrase?
 

grahamperrin

Son of Beastie

Reaction score: 822
Messages: 2,647

… Surely it can't use X for rendering. Does it use the kernel framebuffer …

I'm not doubting that it works, I'd just like to understand how it works :)
If you can just point me to some documentation …

<https://github.com/sddm/sddm#readme> begins, "SDDM is a modern display manager for X11 and Wayland …".

Wayland aside, this might help to understand how things can work. Here, with graphics hardware that requires radeonkms, normally:

Code:
% date; uptime ; kldstat | grep -i -e radeon -e drm
Tue 12 Oct 2021 04:31:45 BST
 4:31a.m.  up 20:22, 6 users, load averages: 0.43, 0.75, 0.87
16    1 0xffffffff838ad000   150c80 radeonkms.ko
17    2 0xffffffff839fe000    7f548 drm.ko
21    1 0xffffffff83a9d000     3258 radeon_TURKS_pfp_bin.ko
22    1 0xffffffff83aa1000     3658 radeon_TURKS_me_bin.ko
23    1 0xffffffff83aa5000     2cd8 radeon_BTC_rlc_bin.ko
24    1 0xffffffff83aa8000     7ef8 radeon_TURKS_mc_bin.ko
25    1 0xffffffff83ab0000     8138 radeon_TURKS_smc_bin.ko
26    1 0xffffffff83ab9000    341f0 radeon_SUMO_uvd_bin.ko
%

Order and timing

Less normally … if kld_list="drm" and if sddm_enable="NO" and if x11-drivers/xf86-video-ati is installed then service sddm onestart will, amongst other things, lead to load of radeonkms.ko and related kernel modules after drm.ko:

Code:
% date; uptime ; kldstat | grep -i -e radeon -e drm
Tue 12 Oct 2021 05:22:14 BST
 5:22a.m.  up 10 mins, 7 users, load averages: 0.43, 1.22, 0.83
13    3 0xffffffff83893000    7f548 drm.ko
38    1 0xffffffff839e6000   150c80 radeonkms.ko
40    1 0xffffffff83b46000     3258 radeon_TURKS_pfp_bin.ko
41    1 0xffffffff83b4a000     3658 radeon_TURKS_me_bin.ko
42    1 0xffffffff83b4e000     2cd8 radeon_BTC_rlc_bin.ko
43    1 0xffffffff83b51000     7ef8 radeon_TURKS_mc_bin.ko
44    1 0xffffffff83b59000     8138 radeon_TURKS_smc_bin.ko
45    1 0xffffffff83b62000    341f0 radeon_SUMO_uvd_bin.ko
%
 
OP
Geezer

Geezer

Aspiring Daemon

Reaction score: 449
Messages: 767

Regarding autologin: I am sure you can do that without a display manager.

Yes, quite possible. Have run in crontab for an ordinary user @reboot startxfce. Works a treat.

Regarding switching to an alternative desktop: Why would one use more than one desktop?

That is only as valid as asking why anyone would want to switch to an alternative text console <alt><F*>
 

kpedersen

Son of Beastie

Reaction score: 2,153
Messages: 3,001

Which types of interfaces does a login manager actually use? Surely it can't use X for rendering.
XDM specifically does launch an Xorg session (preferably not as root). The user logs in and then the login manager transfers access / ownership of the UNIX socket files (i.e in /tmp/) to the user as well as copying over the Xauth / Xauthority related files.

When the user finishes their session (and their .xsession script finishes), the Xserver is restarted entirely (you may notice some flickering here) and the XDM is started up again. It is actually fairly straight forward, how it works. Though some do it slightly differently.

XDMCP is quite a different thing and is rarely used (or at least externally listening. It is still the main (only?) method for enterprise inetd VNC). This basically just listens on a UDP port for requests and then simply "calls" back to the requesting Xserver to make a connection. In most cases this Xserver is simply Xvnc.
 

obsigna

Daemon

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Messages: 1,295

I agree, no-single-body need a display manager. If you setup a multiuser device, then it is quite handy, because it nicely handles logins and logouts of different persons with different skills.

I ship FreeBSD systems for controlling electrochemical laboratory devices (potentiostats/galvanostats) with gdm/GNOME3. While it happens, that those devices are used by one scientist only, it is a common use case in labs that expensive equipment is shared by several people. In the latter case if each one got an own account, the measurement curves are stored within the home directory of the currently logged-in user, and each may fiddle with his/her own files and without changing the login not with that of others.

In commercial laboratories, offering customer services, it is a nice feature to create a user account for recurring customers, besides operator accounts. By this way, even if different lab workers execute the service, programmed settings and the resulting files of the measurements land in one well known place for each customer without mixing it with other measurements.

Once again, a single user having a single user DE on his single user laptop, which is prohibited to be touched even by his girl friend, does not need a DM.
 

jbodenmann

Well-Known Member

Reaction score: 234
Messages: 447

I ship FreeBSD systems for controlling electrochemical laboratory devices (potentiostats/galvanostats) with gdm/GNOME3.
Would love to get a link to those devices and/or some more technical information :)
 

obsigna

Daemon

Reaction score: 899
Messages: 1,295

Would love to get a link to those devices and/or some more technical information :)
https://cyclaero.com/de/simulations/
https://cyclaero.com/en/simulations/
https://cyclaero.com/pt/simulations/

I set up a simulation (a device and a dummy cell) with my software controller on an AWS server in Frankfurt:

Username: test
Password: cydaq

There is another simulation running here in Brazil (same username and password):

However, from Switzerland the server in Frankfurt must be more responsive.

I am a German living in Brazil and I am in cooperation with the traditional Potentiostat developer and supplier Bank Elektronik in Germany. I am responsible for the controller including the operating system (FreeBSD) and the measurement daemon (CyDAQec) and the analysis software (CVA). The controller can be used together with various systems from Bank. It can be used completely headless as well, like the simulations do suggest. The analysis software runs on macOS and Windows.

Most probably I will resettle to Germany in the foreseeable future.
 

astyle

Daemon

Reaction score: 634
Messages: 1,438

Yes, quite possible. Have run in crontab for an ordinary user @reboot startxfce. Works a treat.
Crontab with autologin??? that's not making much sense. I think people really should be in the habit of typing in the password. This really amounts to treating your computer like a grocery store that has automatic sliding doors installed at the front entrance, AND cash registers that don't have locks.
 

kpedersen

Son of Beastie

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I think people really should be in the habit of typing in the password. This really amounts to treating your computer like a grocery store that has automatic sliding doors installed at the front entrance, AND cash registers that don't have locks.
Ultimately unless you have an encrypted hard drive, typing in your password for "security" at a local machine is little bit of an illusion. It is very easy to bypass and access files via a boot disk.

If you have your BIOS locked, most machines can just be reset by taking the battery out for 30 seconds.
 

astyle

Daemon

Reaction score: 634
Messages: 1,438

Ultimately unless you have an encrypted hard drive, typing in your password for "security" at a local machine is little bit of an illusion. It is very easy to bypass and access files via a boot disk.

If you have your BIOS locked, most machines can just be reset by taking the battery out for 30 seconds.
Yeah, but you'd need physical access to the hard drive.
 

astyle

Daemon

Reaction score: 634
Messages: 1,438

https://cyclaero.com/de/simulations/
https://cyclaero.com/en/simulations/
https://cyclaero.com/pt/simulations/

I set up a simulation (a device and a dummy cell) with my software controller on an AWS server in Frankfurt:

Username: test
Password: cydaq

There is another simulation running here in Brazil (same username and password):

However, from Switzerland the server in Frankfurt must be more responsive.

I am a German living in Brazil and I am in cooperation with the traditional Potentiostat developer and supplier Bank Elektronik in Germany. I am responsible for the controller including the operating system (FreeBSD) and the measurement daemon (CyDAQec) and the analysis software (CVA). The controller can be used together with various systems from Bank. It can be used completely headless as well, like the simulations do suggest. The analysis software runs on macOS and Windows.

Most probably I will resettle to Germany in the foreseeable future.
Interesting info, but I think it's veering off-topic. I fail to see the connection between a couple topics:
  1. Your topic: servers in different countries trying to communicate (This is most likely a bandwidth issue)
  2. Thread's topic: how Xorg is organized on a single machine.
Also - I think it's bad taste to talk about real-life setups on the Internet, especially if it's your job. Solving a specific problem without divulging real-life job details - that's OK. But name-dropping - I don't think that will fly.
 
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