[PATCH] vesafb: Document mtrr boot option usage

Document mtrr boot option usage to Documentation/fb/vesafb.txt.

Signed-off-by: Antonino Daplas <adaplas@pol.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/Documentation/fb/vesafb.txt b/Documentation/fb/vesafb.txt
index 814e2f56a6ad35ce367e2d542769664c8b6641f3..62db6758d1c1050db42b638ad4d42dc06809c68b 100644 (file)
--- a/Documentation/fb/vesafb.txt
+++ b/Documentation/fb/vesafb.txt
@@ -144,7 +144,21 @@ vgapal     Use the standard vga registers for palette changes.
        This is the default.
 pmipal Use the protected mode interface for palette changes.
 
        This is the default.
 pmipal Use the protected mode interface for palette changes.
 

-mtrr   setup memory type range registers for the vesafb framebuffer.
+mtrr:n setup memory type range registers for the vesafb framebuffer
+       where n:
+             0 - disabled (equivalent to nomtrr)
+             1 - uncachable
+             2 - write-back
+             3 - write-combining (default)
+             4 - write-through
+
+       If you see the following in dmesg, choose the type that matches the
+       old one. In this example, use "mtrr:2".
+...
+mtrr: type mismatch for e0000000,8000000 old: write-back new: write-combining
+...
+
+nomtrr  disable mtrr

 
 vremap:n
         remap 'n' MiB of video RAM. If 0 or not specified, remap memory
 
 vremap:n
         remap 'n' MiB of video RAM. If 0 or not specified, remap memory