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System Freeze on Switch user

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  • System Freeze on Switch user

    I'm running Ubuntu 8.1 64 bits.
    Have 4g of ram. using radeon 3650 card

    whenever i do a switch user, the system freezes.
    If i do a logout and the log in all works.

    This issue has been going on now for approx 6 months. I thought the newest ubuntu & ati drivers would solve it.
    Any ideas if this is specific to myhardware or if other users are also facing it.

    Any ideas on how to solve it ?

  • #2
    Has it ever worked with this specific HW combination?
    If it has, then it was likely a software change at that time. Please check your package manager logs to see if they go back that far.

    If it hasn't:
    Remove some RAM. Some systems have funky configuration needs if you have 4GB or more. If this fixes it, you may need to change BIOS settings.

    Update your BIOS. Some BIOSes have bugs in how they detect and configure your hardware.

    Please get dmesg and Xorg.0.log from a crash, if possible.


    • #3
      I have the same problem, and I've had it since I bought my 3870. My old X600 worked perfectly with the same hardware.
      It only happens with the fglrx driver though.
      See this bug at launchpad for more frustrated users: #112518


      • #4
        Odur, thanks for the info. Your link also reports it happening with nvidia drivers as well. There seem to be at least 2 bugs with similar profiles here, possibly more. One is fixed by disabling SyncToVblank in compiz (causes hard lock with white screen). Another is an invisible login prompt. I get this with OpenGL screensavers. There may be another bug as well.

        4GB RAM w/ bad BIOS causes problems
        IRQ settings causes problems
        disabling APIC causes problems
        compiz w/ SyncToVblank causes problems
        fglrx doesn't seem to work right with some newer cards
        xorg may have its own issues

        milanvora, is the whole system locked (not pingable) or just the console? (display, keyboard, mouse) Do you get white screen or black?


        • #5
          Also, OpenGL screensavers can cause problems

          Try disabling screen saver (set to blank only)


          • #6
            When I try to switch user with fglrx loaded the system gets totally unresponsive. It's not pingable, no ssh, no nothing. A total and complete hard lock with a black screen.


            • #7
              Odur, Does it still lock if you disable composite? Or if you enable it? Some people have reported <i>enabling</i> composite can fix it.

              Also, try disabling DRI in xorg.conf.


              • #8
                I thought that composite was enabled by default nowdays?
                Allright, I'll test diffrent combos of composite and DRI after work, but I'm not that hopeful.


                • #9
                  I have the same problem with fglrx.

                  I had no problems until I switched my (very) old Matrox card for an ATI 3450 6 months ago. Since using fglrx I can't switch user. I can switch user if I use radeonhd driver, but then I can't watch video due to lack of driver support.
                  Therefore the problem is clearly in fglrx.

                  Perhaps there is a config change that can be done to fix this? I'm using default config.
                  However, this issue has been mentioned repeatedly over the last 6 months (at least), and the ATI devs response was along the lines of "switch user? who uses that?", so don't hold your breath waiting for a fix because they don't really seem to care.

                  Give it long enough and radeonhd will be usable. Of course, your video card might be obsolete by then...


                  • #10
                    I am running 64bit Ubuntu Hardy 8.04 LTS. I too have the problem of screen freezing and system becoming unresponsive on switch user in Gnome with the fglrx driver. Works fine with radeonhd, but then I get no 3d acceleration on my 4670 card!

                    To AMD/ATI: When will this problem be fixed? I see it still in the latest Catalyst 8.12


                    • #11
                      Still happens in fglrx 9.1. Switch user and you go straight to hard-lock hell.

                      Hey, bridgeman. Would you be kind and pass this information to the fglrx-developers. I can't see no explanation other than they don't know about this bug.


                      • #12
                        Just to be clear, a problem with VT switch or user switch is usually not a driver bug per se; this is one of the ugly weaknesses of the current Linux graphics model which KMS is intended to fix.

                        When you do a user switch you are handing off control from one driver to another (in this case to a kernel driver we didn't write and which varies from distro to distro) and if the N drivers don't all treat the hardware in the same way then "unspecified bad things" happen. It's not a question of "fixing the bug", but more of stuffing the driver full of tweaks and workarounds for each problematic distro and kernel you encounter.

                        I have to think that eventually we will be able to duplicate all of the problem situations and put in tweaks for all of them (there are only so many different ways to run graphics drivers in the kernel). The open source drivers seem to be ahead in that respect because they bring the source code to the system that is having problems; in the closed source case we need to be able to reproduce the problem you are seeing on a system our developers can touch, which is much more difficult than you might imagine. Most of the posts here assume that every bug visible on user X's system also occurs on our development and test systems, but that is simply not the case.
                        Last edited by bridgman; 01-31-2009, 11:10 AM.


                        • #13
                          Ok, so you say that this is not a bug in the fglrx driver, although it's only happening when the fglrx driver is in use? All the other drivers are able to switch user without any problem. Did I understand you correctly?

                          Then the question is: What the h-ll can I do to help fix this?


                          • #14
                            Pretty much. I guess the two main points I am trying to make are :

                            1. This isn't something you fix once, it's more like cutting the grass; new combinations of other components keep showing up and every time they do you need to tweak the driver to deal with the new quirks

                            2. This isn't something that happens on our systems and we ignore; each time there's a problem we need to pretty much duplicate the user's system in house to repro the problem so that a developer can do something about it. We usually pick off a couple of these problems every month but there's no "magic fix" that will make all the problems go away; you just accumulate the tweaks over time.

                            Make sense ? AFAIK these kind of problems usually need to be addressed by changing fglrx, at least that's what is done today. I have a nagging feeling that this is one of those "chasing a problem around the room" issues which would be better solved by changing the kernel drivers to make them more consistent (and consistent with our drivers) but I haven't had a chance to look into that.

                            In terms of helping to fix it, I think the best thing is making sure that when our devs have time to pick off a few more VT issues that the information in the informal bugzilla is clear and complete. Notes about whether the problem occurs with the open source drivers (and which version of the drivers you were using) is probably also a big help, but I need to confirm that with the devs.
                            Last edited by bridgman; 01-31-2009, 12:00 PM.


                            • #15
                              I'm struggling to understand your point here.

                              If I switch user, I am going from an X-session using fglrx to another X-session using fglrx (or I would be if it didn't lockup). Where is the other driver involvement you speak of?

                              I don't have any problem going from X-session to VT and back again, just when trying to start an additional X-session.

                              I've never heard of any other driver being unable to do this, and I've tried quite a few over the 10 years I've been using Linux. It works fine with radeonhd, but last time I tried that driver I couldn't watch video so it was no use to me.

                              Do you know of anyone who can successfully switch user using the fglrx driver? Lots of people have mentioned here that they can't do it, and I've never seen anyone say that it works for them.

                              I've tried on Debian and Ubuntu with 2 different ATI cards, and it didn't work on any setup I've attempted it on.
                              Last edited by duffster; 01-31-2009, 12:42 PM.