Re: [Dri-devel] mga-dualhead and dri

[Klaus W. R. <kla...@ma...>]

------Original Message------
From: Gareth Hughes <ga...@va...>
To: Klaus Wilhelm Rose <kla...@ma...>
Sent: March 12, 2001 6:26:26 PM GMT
Subject: Re: [Dri-devel] mga-dualhead and dri


Klaus Wilhelm Rose wrote:
>
> This patch makes dri and mga-dualhead support work again for the current
cvs
> tree (direct rendering for the primary screen and indirect rendering for
the
> second screen). I'm interested if anybody has problems with stability (for
> me it runs quite stable with several instances of gears on both screens).

Can you explain the need for this part of the patch?

--- .../linux/drm/xf86drmHash.c Tue Jul 11 13:41:06 2000
+++ .../linux/drm/xf86drmHash.c  Mon Mar  5 21:17:41 2001
@@ -234,7 +234,7 @@
{
HashTablePtr  table = (HashTablePtr)t;
HashBucketPtr bucket;
-
+    if (!table) return -1;
if (table->magic != HASH_MAGIC) return -1; /* Bad magic */

bucket = HashFind(table, key, NULL);

-- Gareth


Without this patch a programm which is started on the second screen (using
indirect rendering, direct rendering enabled on the primary screen) will
terminate with a segfault since drmHashLookup is called with a value of zero
for table.

The fix seems reasonable since in __driMesaFindDrawable a value of NULL is
used to indicate a drawable that is not bound to a direct rendering context,
this is related to a return value of -1 in drmHashLookup.

Klaus


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