Announcement

Collapse
No announcement yet.

Intel KMS vs. UMS With Ubuntu 10.04

Collapse
X
  • Filter
  • Time
  • Show
Clear All
new posts

  • #16
    Originally posted by mendieta View Post
    Strong wording, ah?. The reason they went for UMS is that some hardware is just not working with KMS, and I think that's a good reason.You want your hardware to work. Then, you may prefer this or that feature, but at a minimum you need the display to ... well, display
    Wouldn't using separate packages and some modalias definitions as they do with the multiple nvidia blobs be preferable to backporting? At least the users would KMS capable hardware would get some of the newer fixes that can't be easily backported.

    Comment


    • #17
      Originally posted by kurros View Post
      Wouldn't using separate packages and some modalias definitions as they do with the multiple nvidia blobs be preferable to backporting? At least the users would KMS capable hardware would get some of the newer fixes that can't be easily backported.
      Emmm... Nope.

      I have a Intel IGP where every thing works extremely fine with KMS until I try to hook it up to a TV over svideo. I have screen output but it gets garbled, and it seems dependent on things like moving windows, 3d and so on (it is not mesa, removed the mesa drivers and issue still there).

      With UMS, same driver versions, everything works just fine.

      Comment


      • #18
        Originally posted by FireBurn View Post
        I think they've played with the kernel drm, libdrm, xorg-server as well as the drivers
        Ubuntu Lucid uses a vanilla version of the intel driver 2.9.1 (which supports UMS and KMS ootb), and a vanilla version of libdrm (version 2.4.18).

        The Xserver is version 1.7.6 plus udev-patches from Xserver 1.8.

        The kernels biggest change is the backported the drm-stack from version 2.6.33. The other changes are minimal (e.g. a small patch for ureadahead, a patch for minimizing kernel log output etc.)

        In other words :

        Ubuntu Lucid is not as heavily patched as some people believe.

        Comment


        • #19
          Every distro patches their stuff. It's expected that they patch it since the vanilla kernel.org kernel is just shit when it comes to stability.

          The days were people used the vanilla kernel are long gone. Dead with the 2.4 series.

          The DRM stuff is always kinda separate anyways. Historically they always maintained DRM kernel drivers separate from the vanilla kernel that had newer stuff and more features. Out of things to backport, it's probably one of the lesser big deals.


          ------------------------

          The UMS vs KMS thing is stupid, though. Instead of forward porting UMS support the correct thing is just to fix KMS.

          Why?

          * Because your going to have to fix KMS anyways eventually, so your just going to make more work for yourself in the long run. You might as well get it over with and fix it correctly right now.

          * UMS introduces more bugs and things to support on your own, so actually instead of fixing bugs your more then likely create MORE bugs. By forward porting stuff like this your making the software worse. There are good reasons why the Intel folks dropped it.

          * Forcing users to choose between modesetting methods to get the hardware working when 98% of the target audience has no f-ng clue what that even means is shitty OS design. This means that even if your forward porting UMS to work around KMS bugs the vast majority of people that will run into those specific KMS bugs will never benefit from the presence of UMS since it's beyond their means to use it.

          Users whose TV out is broken are not going to say to themselves 'Oh, maybe I should hack around with /etc/X11/xorg.conf and see if UMS option will make my TV work...'; They are just going to not use TV out.

          Comment


          • #20
            Originally posted by drag View Post
            The UMS vs KMS thing is stupid, though. Instead of forward porting UMS support the correct thing is just to fix KMS.

            Why?

            * Because your going to have to fix KMS anyways eventually, so your just going to make more work for yourself in the long run. You might as well get it over with and fix it correctly right now.

            * UMS introduces more bugs and things to support on your own, so actually instead of fixing bugs your more then likely create MORE bugs. By forward porting stuff like this your making the software worse. There are good reasons why the Intel folks dropped it.

            * Forcing users to choose between modesetting methods to get the hardware working when 98% of the target audience has no f-ng clue what that even means is shitty OS design. This means that even if your forward porting UMS to work around KMS bugs the vast majority of people that will run into those specific KMS bugs will never benefit from the presence of UMS since it's beyond their means to use it.

            Users whose TV out is broken are not going to say to themselves 'Oh, maybe I should hack around with /etc/X11/xorg.conf and see if UMS option will make my TV work...'; They are just going to not use TV out.
            And that is why a driver/distro should use KMS by _default_, but still have a *WORKING ALTERNATIVE* for all those cases when KMS does not work. Remember 9.04 should be supported for a long time, and that without having to make major upgrades to the kernel/drm code just because some vendor decides to drop support for stuff prematurely.

            Comment


            • #21
              Originally posted by drag View Post
              Users whose TV out is broken are not going to say to themselves 'Oh, maybe I should hack around with /etc/X11/xorg.conf and see if UMS option will make my TV work...'; They are just going to not use TV out.
              But for us who NEED TV-out it IS an option. For me I stumble over it while debugging (all on my own, mind you, as I have filed a bugreport, but noone in the intel team seems to want to help (possibly because it is a hell to debug this kind of things without be able to have hands-on time with a failing computer)) and I *AM* very happy that UMS is an option for me.

              Comment


              • #22
                Originally posted by phoronix View Post
                Last week we published benchmarks looking at the ATI Radeon KMS vs. UMS performance and found the user-space mode-setting support with the ATI driver (that is also limited to using DRI1 with these older code-paths) [...]
                That's exactly why there's less difference with the Intel drivers: they're still using GEM/DRI2 with UMS.

                Comment


                • #23
                  nomodeset instead of i915.modeset=0

                  Originally posted by phoronix View Post
                  Kernel mode-setting support can be toggled at boot-time by adding i915.modeset=0 to the GRUB kernel boot line to boot with the user-space mode-setting support
                  Kernel mode-setting can be disabled by adding nomodeset to the Grub kernel boot line.

                  I had to disable kernel mode-setting on my i965 Intel Mobile GM965/GL960 because it did weird things with a panning desktop and I couldn't adjust screen brightness in Ubuntu Lucid Lynx.

                  Disabling kms with nomodeset fixed these problems.

                  Comment

                  Working...
                  X