configuration of mtrr described

CVS patchset: 284
CVS date: 2001/07/16 08:14:28

1 files changed, 27 insertions, 0 deletions

diff --git a/doc/README.freebsd b/doc/README.freebsd
index eec8c5bac..72d5f2e65 100644
--- a/doc/README.freebsd
+++ b/doc/README.freebsd
@@ -10,6 +10,33 @@ kern.ipc.shmmax=67108864
 kern.ipc.shmall=32768
 
 
+mtrr on freebsd
+---------------
+
+setting up the caching behaviour of the memory on the graphics board.
+
+what is being done with the mtrr support on linux is to set the caching
+type of the memory of the graphics board to 'write-combine' mode.
+that way the performance of big writes into this memory should be faster.
+
+it seems that the same can be achieved on freebsd by executing:
+
+  memcontrol set -b <base-address> -l <length> write-combine
+
+for example on my system i executed:
+
+  memcontrol set -n 0xd8000000 -l 0x02000000 write-combine
+
+i got the base-adress by executing 'startx' and looking at the output.
+
+it seems to be dangerous to change the cache setting of the graphics memory
+while xfree is running - at least i managed to have my system freeze that
+way. so better do it on the commandline.
+
+this tip is still subject of research, so it might be incorrect - please
+report any further information on this topic to the xine-user list.
+please also report success or non-success on xine-user if you have the time.
+
 
 playing video cd on freebsd
 ---------------------------