Comment 143 for bug 541511

Hi,

On Mon, Apr 19, 2010 at 7:39 AM, Geir Ove Myhr <email address hidden> wrote:
> Vlad, thank you for taking an interest in helping. We have followed the
> upstream bug report (freedesktop-bugs #27187 at the top of this page)
> and we know about the fix.
>
>>"Anyway the i855GM issues have just been radically fixed by Daniel Vetter, you can find the patch and the complete kernel
> sources archive here:http://www.iragan.com/linux/i855GM/"

I took a look over the patches; whilst there is a radical re-working
of things - what is interesting is seeing what was shipped
(supposedly, this is from the comment and not verified) in Fedora 13.
They have a 2 line patch.

From http://www.iragan.com/linux/i855GM/old_patches/drm-intel-big-hammer.patch

RedHat patch used in Fedora Core 13.

This patch prevents instantaneous crashes when starting Xorg.

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 37427e4..08af9db 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -2553,6 +2553,11 @@ i915_gem_execbuffer(struct drm_device *dev, void *data,

  mutex_lock(&dev->struct_mutex);

+ /* We don't get the flushing right for these chipsets, use the
+ * big hamer for now to avoid random crashiness. */
+ if (IS_I85X(dev) || IS_I865G(dev))
+ wbinvd();
+
  i915_verify_inactive(dev, __FILE__, __LINE__);

  if (dev_priv->mm.wedged) {

> It is the kernel that needs an alternative version, changing xorg will
> not fix this. It's not too hard to compile, and I would already have
> done this if I had a i386 installation of Lucid available.

It may be worthwhile asking the kernel guys about incorporating this
into the kernel. I am compiling 2.6.32-21-generic to test this out to
see if it works for me. I'll report back in a few hours.

Cheers,
Anand