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  • bridgman: Yeah, there was a new Intel driver which relied on the downloaded data to overwrite old data in newly allocated memory buffers. Nothing wrong with that AFAIK (presumably it was done as a performance optimization) but it interacted badly with the no-backfill patch, allowing users to see old screen info which potentially could have been from another user's session.

    The problem was flagged as a security issue and removing the patch was the most expedient way to close it. The result was that any driver running XAA acceleration became very slow when performing certain operations. Felix implemented the backclear patch which performed the same function as no-backfill but also added code to clear out the destination buffer, eliminating the security hole on Intel GPUs while still providing good performance on XAA drivers.

    When the 10.6 driver comes out, check the release notes to see if the new 2D acceleration code is enabled by default. If so, give that driver a try and it should address some of the problems you are seeing.
    Hmm, that's interesting. Let me see if follow u..
    Is 2D acceleration code DISABLED by default in 10.5? If that's the case...why? and wouldn't another solution to my problem be to just edit something that enables 2D acceleration?
    So, XAA controls 2D acceleration, and X server is tied in with that (in layman terms), which is why a prepatched x server will solve my problem as well right?
    And where did fglxr go 'wrong' where all this is concerned?

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    • The new 2D accel code from amd is a little unstable right now (a few graphical glitches) - basically it's not ready. Nor has it been officially announced by AMD (someone violated their NDA and leaked info about it). So it's not yet enabled by default.

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      • adamk:
        Ah interesting.I guess i'll be using Ubuntu's default for the while until i'm sure ATI's proprietary will give me the results i want. Now i'm not longer surprised that fglrx and 10.5 both lagged, cuz there's not much difference between them. I also assume, that the same 'fix' will probably work for either version. THank you for the clarification

        mirv:
        By new 2d accel code are you referring to the one that 10.6 is going to have? I assume there's a 10.6 beta out already? or are you referring to the 2D accel code in 10.5? I was asking if in 10.5 that code is disabled by default and if so how to enable it. If that code is unstable then it doesn't really matter

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        • Originally posted by hotnikkelz View Post
          adamk:
          Ah interesting.I guess i'll be using Ubuntu's default for the while until i'm sure ATI's proprietary will give me the results i want. Now i'm not longer surprised that fglrx and 10.5 both lagged, cuz there's not much difference between them. I also assume, that the same 'fix' will probably work for either version. THank you for the clarification

          mirv:
          By new 2d accel code are you referring to the one that 10.6 is going to have? I assume there's a 10.6 beta out already? or are you referring to the 2D accel code in 10.5? I was asking if in 10.5 that code is disabled by default and if so how to enable it. If that code is unstable then it doesn't really matter
          No 10.6 beta out - but the 2D acceleration code has been present for a little while and can be enabled with:
          aticonfig --set-pcs-str=DDX,Direct2DAccel,TRUE
          or disabled with:
          aticonfig --del-pcs-key=DDX,Direct2DAccel

          (as root, or sudo, or whatever takes your fancy)

          Consider yourself warned however that it will have some graphical glitches!

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          • Originally posted by hotnikkelz View Post
            Is 2D acceleration code DISABLED by default in 10.5? If that's the case...why? and wouldn't another solution to my problem be to just edit something that enables 2D acceleration?

            So, XAA controls 2D acceleration, and X server is tied in with that (in layman terms), which is why a prepatched x server will solve my problem as well right?

            And where did fglxr go 'wrong' where all this is concerned?
            2D acceleration is enabled by default, but it uses the standard XAA interface which does not happen to accelerate the specific download operation required when running an unpatched X server with a compositor and unminimizing a window etc...

            Patching the X server eliminates the download when unminimizing -- the download is normally wasted anyways because the downloaded data usually gets over-written immediately after the transfer. Unfortunately the patch has been gone for a year or so and a few more programs have started relying on the downloaded data. As an example, if you are running newer versions of KDE you will see small black squares briefly appearing when running with a patched X server, corresponding to areas where the downloaded data would have been used.

            The only thing fglrx does "wrong" here is that it uses the XAA interface for acceleration. The upcoming 2D acceleration code replaces the XAA standard with a new and larger set of functions, including one which accelerates the download operation.

            As others have posted, the currently shipping drivers include in-development versions of the new acceleration code, but since the new code has not been completed we disable it by default. Future versions of the driver (probably this month's release) will include newer versions of the code and at some point it will be considered ready to enable by default. Until then your options are (a) use a patched X server, (b) use the open source drivers which are enabled by default when installing Lucid, (c) enable the work-in-process accel code in the 10.5 driver and see how it works on your system, (d) live with the delays.

            Given that the new accel code is likely to appear in the next regular driver release I would probably go with option (b).
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            • ohhh ok, i understand much more now *phew*
              Thanks you guys. Must have taken you guys a while to learn the ins and outs of how these things work lol, i'm only now tinkering with linux since it's going to take over the world

              I have one final question i believe. If fglrx (which is basically compiled 10.4 drivers right?) whose 2D accel uses XAA and thus is unable to accelerate the download, what does 10.5's 2D accel code use and do you know how it differs with the even newer 2D accel code in 10.6.
              And yes i will definitely go with option B, time flies fast, I'll be trying to learn the basics of ubuntu during that time

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              • Just to clear up. There are two drivers for your card currently available and being developed:

                FGLRX = Catalyst = proprietary = closed-source = ATi official driver (that's the 10.5 thing you had to download)

                and

                Open Source driver = kernel + Mesa + radeon = "radeon driver" = free driver (that's the thing that is installed on Ubuntu by default)

                If you are going to be playing lots of WINE stuff, you'll need the proprietary drivers. They are very optimized and have latest whizbang, but as you've seen, they have their issues with 2d and video.

                For most regular use (including desktop effects and some native gaming), the open source drivers are a good choice.

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                • "fglrx" is the internal name for the Catalyst Linux Edition proprietary driver, and the string appears in a number of file names and messages. Just two names for the same thing.

                  Note that the fglrx driver installed by Ubuntu is slightly different from the final 10.4 driver available at amd.com - we gave the Ubuntu folks a pre-release version of what would eventually become the 10.4 driver in order to meet their internal schedules. All three versions (Ubuntu, final 10.4 and 10.5) use XAA by default, and the XAA code is the same other than bug fixes, so unless you are forcing on the unreleased "new 2D" code you should see the same behaviour on all three.

                  If you force the unreleased "new 2D" code on (recognizing that it is *not* ready for normal use yet) then 10.5 is probably quite a bit better than 10.4, but still not good enough for us to enable it by default.
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                  • How about the recently released 10.6 drivers? Isn't the new 2D acceleration feature complete-ish?

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                    • Yes, but when I made that post they were soon-to-be-released, not recently-released
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