Re: agpgart issue on 2.6.1-rc1-bk3 (x86-64)

[Dave Jones <davej@redhat.com>]

On Sun, Jan 04, 2004 at 12:28:22PM +1100, Srihari Vijayaraghavan wrote:
 > Hello,
 > 
 > I see this message in the 2.6.1-rc3-bk3 kernel log:
 > agpgart: Detected AGP bridge 0
 > agpgart: Too many northbridges for AGP
 > 
 > This results in <100 FPS in glxgears, and I am unable to play the tuxracer 
 > game :-). With 2.6.0-x8664-1 however I get 450 FPS (approx), and all was 
 > well.
 > 
 > Upon applying this patch (making it identical to 2.6.0-x86-64 that is):
 > --- 2.6.1-rc1-bk3/drivers/char/agp/amd64-agp.c.orig     2004-01-04 
 > 01:06:20.000000000 +1100
 > +++ 2.6.1-rc1-bk3/drivers/char/agp/amd64-agp.c  2004-01-04 01:06:50.000000000 
 > +1100
 > @@ -16,11 +16,7 @@
 >  #include "agp.h"
 > 
 >  /* Will need to be increased if AMD64 ever goes >8-way. */
 > -#ifdef CONFIG_SMP
 >  #define MAX_HAMMER_GARTS   8
 > -#else
 > -#define MAX_HAMMER_GARTS   1
 > -#endif

Wrong fix.  Amongst another bunch of AGP fixes going to Linus/Andrew
on Monday is the following..

(Andi also sent me another amd64 update, which I'll merge before
 pushing Linuswards)


diff -urpN --exclude-from=/home/davej/.exclude bk-linus/drivers/char/agp/amd64-agp.c linux-2.5/drivers/char/agp/amd64-agp.c
--- bk-linus/drivers/char/agp/amd64-agp.c	2003-10-17 20:53:49.000000000 +0100
+++ linux-2.5/drivers/char/agp/amd64-agp.c	2003-12-02 02:05:32.000000000 +0000
@@ -357,11 +356,18 @@ static __devinit int cache_nbs (struct p
 		}
 		hammers[i++] = loop_dev;
 		nr_garts = i;
-		if (i == MAX_HAMMER_GARTS) { 
+#ifdef CONFIG_SMP
+		if (i > MAX_HAMMER_GARTS) { 
 			printk(KERN_INFO PFX "Too many northbridges for AGP\n");
 			return -1;
 		}
+#else
+		/* Uniprocessor case, return after finding first bridge.
+		   (There may be more, but in UP, we don't care). */
+		return 0;
+#endif
 	}
+
 	return i == 0 ? -1 : 0;
 }
 

 
-- 
 Dave Jones     http://www.codemonkey.org.uk