Bug 57609 - i915 driver reports too large maximum viewport
Summary: i915 driver reports too large maximum viewport
Status: RESOLVED WONTFIX
Alias: None
Product: Mesa
Classification: Unclassified
Component: Drivers/DRI/i915 (show other bugs)
Version: 9.0
Hardware: Other All
: medium normal
Assignee: Ian Romanick
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Depends on:
Blocks: 67224
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Reported: 2012-11-27 12:09 UTC by karaluh
Modified: 2013-07-23 18:02 UTC (History)
1 user (show)

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i915 platform:
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Description karaluh 2012-11-27 12:09:12 UTC 
As in summary, glxinfo -l reports GL_MAX_VIEWPORT_DIMS = 16384, 16384 which results in too slow to be unusable dual screen composited setup. Original bug report here:
https://bugs.kde.org/show_bug.cgi?id=308439
Comment 1 Ian Romanick 2013-07-23 17:02:41 UTC 
I suspect KDE is using the advertised maximum viewport incorrectly.  The OpenGL spec requires the value be fairly large.  Section 2.12.1 (Controlling the Viewport) says:

    The maximum viewport dimensions must be greater than or equal to
    the larger of the visible dimensions of the display being rendered
    to (if a display exists), and the largest renderbuffer image which
    can be successfully created and attached to a framebuffer object
    (see chapter 4).

X allows the user to create very large windows and pixmaps... even larger than the display itself.  As a result, we can't advertise a small value here and still comply with the spec.

If KDE wants to know sizes that will be "fast," GL_MAX_RENDERBUFFER_SIZE is likely a better metric.

Unless there is additional feedback, I'm going to close this as WONTFIX.
Comment 2 Ian Romanick 2013-07-23 18:02:42 UTC 
Looking at the patch in the upstream bug, it looks like they've found the correct solution.  Closing.

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