Nouveau - Sep 2009 - [Bug 23741] New: Driver pixmaps cause pushbuf validation failure on mode change (nv28, KMS)

http://bugs.freedesktop.org/show_bug.cgi?id=23741

           Summary: Driver pixmaps cause pushbuf validation failure on mode
                    change (nv28, KMS)
           Product: xorg
           Version: git
          Platform: x86-64 (AMD64)
        OS/Version: Linux (All)
            Status: NEW
          Severity: normal
          Priority: medium
         Component: Driver/nouveau
        AssignedTo: nouveau at lists.freedesktop.org
        ReportedBy: pq at iki.fi
         QAContact: xorg-team at lists.x.org


Roughly latest git of ddx, drm and libdrm. Xorg-server git version some weeks
old. Confirmed with a full nouveau/linux-2.6 git kernel.

NV28, KMS active. Issuing the command 'xrandr -s 800x600' resulted in a
kernel
hang, a live lock one might say. This was worked around in nouveau/linux-2.6 in
the commit "drm/nouveau: bail out if validation fails repeatedly",
which allows
the kernel to fail gracefully, killing only X instead of the whole system.

When 'xrandr -s 800x600' fails, monitor loses signal completely. With
the
kernel workaround in place, X can be restarted and everything is good again.
Note, that sysRq force-fb does restore the mode, but not the virtual console
image.

Setting Option "EXAPixmaps" "false" in xorg.conf disables
the bug, so it is
driver pixmap specific. Likely it does not affect NV50 family, or someone would
have noticed it.


-- 
Configure bugmail: http://bugs.freedesktop.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are the assignee for the bug.

http://bugs.freedesktop.org/show_bug.cgi?id=23741





--- Comment #1 from Pekka Paalanen <pq at iki.fi>  2009-09-06 04:24:48 PST
---
Created an attachment (id=29265)
 --> (http://bugs.freedesktop.org/attachment.cgi?id=29265)
X log of mode change failing


-- 
Configure bugmail: http://bugs.freedesktop.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are the assignee for the bug.

http://bugs.freedesktop.org/show_bug.cgi?id=23741





--- Comment #2 from Pekka Paalanen <pq at iki.fi>  2009-09-06 04:28:53 PST
---
Created an attachment (id=29266)
 --> (http://bugs.freedesktop.org/attachment.cgi?id=29266)
kernel log

The kernel log from boot, with lots of experimenting in between, and the
reported failure at timestamp 16400.079421.


-- 
Configure bugmail: http://bugs.freedesktop.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are the assignee for the bug.

http://bugs.freedesktop.org/show_bug.cgi?id=23741


Pekka Paalanen <pq at iki.fi> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED




--- Comment #3 from Pekka Paalanen <pq at iki.fi>  2009-09-17 12:35:32 PST
---
The original issue seems to be fixed.

First worked around by DRM commit 18895876371e616db9f04652460c1d72174909c3
"drm/nouveau: bail out if validation fails repeatedly"

The proper handling of the effect of the bug, DRM commit
e6c757cc15b32f995f3aed9a4997ed710b740758
"drm/nouveau: protect against validating the same buffer twice"

And the fix to the bug itself in DDX, commit
806eaf6b0b36cb05ca9d883ff4572629812a1d48
"kms: rework fbcon transition"

However, changing mode with xrandr while watching TV (cable-tv-card, gxine,
with Xv most likely) results in X spinning in kernel and giving up in few
minutes. But that's another bug for another day. It too results in monitor
switching off.


-- 
Configure bugmail: http://bugs.freedesktop.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are the assignee for the bug.