Bug 4987 - Xorg does not deal well with aperture < memory
Summary: Xorg does not deal well with aperture < memory
Status: RESOLVED FIXED
Alias: None
Product: xorg
Classification: Unclassified
Component: Driver/Radeon (show other bugs)
Version: git
Hardware: x86 (IA32) Linux (All)
: high normal
Assignee: Xorg Project Team
QA Contact:
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Blocks:
 
Reported: 2005-11-07 18:34 UTC by Saleem Abdulrasool
Modified: 2006-05-08 22:12 UTC (History)
1 user (show)

See Also:
i915 platform:
i915 features:


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Description Saleem Abdulrasool 2005-11-07 18:34:54 UTC
128 MB of RAM on the video card with the following
Aperture size: 4000000
Host Path Control: 70000000

causes the video to be garbled.  The HDP does not specify to use overlapping
aperture, resulting in corrupted video.  Changing the RAM size used by half,
resolves the issue.
Comment 1 Benjamin Herrenschmidt 2005-11-07 18:51:29 UTC
Actually, it's the opposite :) HDP_APER_CNTL does set apertures to overlap which
causes the problem :) We need to detect that case where CONFIG_MEMSIZE >
CONFIG_APER_SIZE and set HDP_APER_CNTL to 1 in this case, thus effectively using
both apertures to map the framebuffer.

However, we also need to figure out what's up with more recent cards & HDP stuff
which might work a bit differently, and we need to fix various assumptions done
about CONFIG_APER_SIZE when setting MC_FB_LOCATION among others (including in
the DRM). The PCI BAR is actually 2*CONFIG_APER_SIZE, not CONFIG_APER_SIZE, and
a setup like this one will make us use both apertures.
Comment 2 Benjamin Herrenschmidt 2005-11-07 18:52:25 UTC
Changing to Drivers/Radeon, the problem is not EXA specific. EXA shows it right
away due to the way it uses VRAM, but it _will_ happen with XAA or anything else
that starts using VRAM above the 64M point.
Comment 3 Michel Dänzer 2006-05-09 02:40:14 UTC
Ben, this is fixed in the xf86-video-ati 6.5.8 release or CVS, right?
Comment 4 Benjamin Herrenschmidt 2006-05-09 08:16:50 UTC
Yes. On some cards by setting HOST_PATH_CNTL properly, on others by limiting the
accessible video RAM, depending on the card's type and version
Comment 5 Michel Dänzer 2006-05-09 15:12:09 UTC
Thanks Ben, closing.


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