Re: 2.6.22-rcX Transmeta/APM regression

[Andrew Morton <akpm@linux-foundation.org>]

On Sat, 30 Jun 2007 00:06:36 -0400 "H. Peter Anvin" <hpa@zytor.com> wrote:

> linux@horizon.com wrote:
> > 
> > Anyway, the patch which introduces the problem is the aptly named 3ebad:
> > 3ebad59056: [PATCH] x86: Save and restore the fixed-range MTRRs of the BSP when suspending
> > 
> > 2.6.22-rc6 plus that one commit reverted successfully does APM suspend
> > (and resume) for me.
> 
> Okay, I would guess that that patch probably touches MTRRs without 
> actually verify that the CPU *has* MTRRs -- the Transmeta Crusoe CPU 
> doesn't have MTRRs.
> 

This?

--- a/arch/i386/kernel/cpu/mtrr/generic.c~i386-mtrr-crash-fix
+++ a/arch/i386/kernel/cpu/mtrr/generic.c
@@ -65,7 +65,8 @@ get_fixed_ranges(mtrr_type * frs)
 
 void mtrr_save_fixed_ranges(void *info)
 {
-	get_fixed_ranges(mtrr_state.fixed_ranges);
+	if (cpu_has_mtrr)
+		get_fixed_ranges(mtrr_state.fixed_ranges);
 }
 
 static void print_fixed(unsigned base, unsigned step, const mtrr_type*types)
_