Re: 2.4.x vs 2.6.x: denormal handling and audio performance

[Lee Revell <rlrevell@joe-job.com>]

On Mon, 2004-08-09 at 21:00, Lee Revell wrote:
> On Mon, 2004-08-09 at 15:19, Fernando Pablo Lopez-Lezcano wrote:
> > Hi all, I've been trying to track weird behavior I'm experiencing when
> > trying to use 2.6.x for "pro audio" applications
>
> In case anyone thinks this is an application bug, here are some links
> pertaining to the P4 denormals-are-zero issue


If the denormals-are-zero bit is the issue then I believe this patch
should fix the problem.

Lee

--- arch/i386/kernel/i387_orig.c	2004-08-09 21:06:00.000000000 -0400
+++ arch/i386/kernel/i387.c	2004-08-09 21:06:05.000000000 -0400
@@ -34,7 +34,7 @@
 		memset(&current->thread.i387.fxsave, 0, sizeof(struct i387_fxsave_struct));
 		asm volatile("fxsave %0" : : "m" (current->thread.i387.fxsave)); 
 		mask = current->thread.i387.fxsave.mxcsr_mask;
-		if (mask == 0) mask = 0x0000ffbf;
+		if (mask == 0) mask = 0x0000ffff;
 	} 
 	mxcsr_feature_mask &= mask;
 	stts();