Index: dri-howto.xml =================================================================== RCS file: /var/cvsroot/gentoo/xml/htdocs/doc/en/dri-howto.xml,v retrieving revision 1.29 diff -u -r1.29 dri-howto.xml --- dri-howto.xml 7 May 2006 12:39:17 -0000 1.29 +++ dri-howto.xml 7 May 2006 14:38:04 -0000 @@ -442,8 +442,66 @@

-A few options may increase performance by up to 30 percent (or more) over the -default. Set them in /etc/X11/xorg.conf. +A few options may increase performance by up to 30 percent (or more) over the +default. Set them in /etc/X11/xorg.conf. However, you will first +need to check that your motherboard and video card support these options. +

+ +

+First, let's see if your video card can support fast writes. We'll do this by +closely inspecting the output from lspci. Specifically, we are looking +at the "VGA compatible controller" information. +

+ +
+# lspci -vv
+01:00.0 VGA compatible controller: ATI Technologies Inc Radeon Mobility M6 LY (prog-if 00 [VGA])
+. . .
+Capabilities: [58] AGP version 2.0
+    Status: RQ=48 Iso- ArqSz=0 Cal=0 SBA+ ITACoh- GART64- HTrans- 64bit- FW+ AGP3- Rate=x1,x2,x4
+
+ +

+While quite a lot of information is produced, we are looking for FW in +the "Status" subsection of the AGP "Capabilities" section. If FW+ is +present in the "Status" line, it means the card supports fast writes. We can +now check if the motherboard supports fast writes. +

+ + +If you do not see FW+, but instead see FW-, you cannot enable +fast writes in xorg.conf. Your card does not support fast writes. + + +

+Now let's make sure the motherboard supports fast writes as well. This time, +look at the "Host bridge" section of your lspci output. +

+ +
+# lspci -vv
+00:00.0 Host bridge: Intel Corporation 82830 830 Chipset Host Bridge (rev 02)
+. . .
+Capabilities: [a0] AGP version 2.0
+    Status: RQ=32 Iso- ArqSz=0 Cal=0 SBA+ ITACoh- GART64- HTrans- 64bit- FW+ AGP3- Rate=x1,x2,x4
+
+ +

+Again, examine the "Status" subsection of your AGP "Capabilities" section. Look +for FW. If you see FW+, your motherboard supports fast writes. +

+ + +Remember, both your video card information and your motherboard information +must show the same FW capability. If either device shows FW- in +"Status", you cannot enable fast writes in xorg.conf. + + +

+Assuming that all has gone well and both your motherboard and video card +support fast writes, let's enable this option in +/etc/X11/xorg.conf and get the best performance out of your +hardware. 

@@ -470,46 +528,6 @@
 enable the appropriate option in your BIOS.
 
 
-
-
 

 If you want to set even more features, check out the feature matrix on