[PATCH] powerpc: enable NAP only on cpus who support it to avoid memory corruption

[PATCH] powerpc: enable NAP only on cpus who support it to avoid memory corruption

[Olaf Hering]

commit 51d3082fe6e55aecfa17113dbe98077c749f724c enabled NAP unconditinally
on all powermacs. Early G3 cpus can not use it, the result is memory corruption.

Only enable powersave_nap in one place: probe_motherboard()
ppc32 gets nap if the cpu supports it
ppc32 smp gets no nap
ppc64 gets nap unconditionally

---
 arch/powerpc/platforms/powermac/feature.c |    8 +++++++-
 arch/powerpc/platforms/powermac/setup.c   |    4 ----
 arch/powerpc/platforms/powermac/smp.c     |    4 ----
 3 files changed, 7 insertions(+), 9 deletions(-)

Index: linux-2.6.16-rc5-olh/arch/powerpc/platforms/powermac/feature.c
===================================================================
--- linux-2.6.16-rc5-olh.orig/arch/powerpc/platforms/powermac/feature.c
+++ linux-2.6.16-rc5-olh/arch/powerpc/platforms/powermac/feature.c
@@ -2513,8 +2513,11 @@ found:
 		/* Nap mode not supported if flush-on-lock property is present */
 		if (get_property(np, "flush-on-lock", NULL))
 			break;
+
+#ifndef CONFIG_SMP
+		/* 32 bits SMP can't NAP */
 		powersave_nap = 1;
-		printk(KERN_INFO "Processor NAP mode on idle enabled.\n");
+#endif
 		break;
 	}
 
@@ -2526,6 +2529,9 @@ found:
 #ifdef CONFIG_POWER4
 	powersave_nap = 1;
 #endif
+	if (powersave_nap)
+		printk(KERN_INFO "Using native/NAP idle loop\n");
+
 	/* Check for "mobile" machine */
 	if (model && (strncmp(model, "PowerBook", 9) == 0
 		   || strncmp(model, "iBook", 5) == 0))
Index: linux-2.6.16-rc5-olh/arch/powerpc/platforms/powermac/setup.c
===================================================================
--- linux-2.6.16-rc5-olh.orig/arch/powerpc/platforms/powermac/setup.c
+++ linux-2.6.16-rc5-olh/arch/powerpc/platforms/powermac/setup.c
@@ -621,10 +621,6 @@ static void __init pmac_init_early(void)
 	/* Probe motherboard chipset */
 	pmac_feature_init();
 
-	/* We can NAP */
-	powersave_nap = 1;
-	printk(KERN_INFO "Using native/NAP idle loop\n");
-
 	/* Initialize debug stuff */
 	udbg_scc_init(!!strstr(cmd_line, "sccdbg"));
 	udbg_adb_init(!!strstr(cmd_line, "btextdbg"));
Index: linux-2.6.16-rc5-olh/arch/powerpc/platforms/powermac/smp.c
===================================================================
--- linux-2.6.16-rc5-olh.orig/arch/powerpc/platforms/powermac/smp.c
+++ linux-2.6.16-rc5-olh/arch/powerpc/platforms/powermac/smp.c
@@ -739,10 +739,6 @@ static void __init smp_core99_setup(int 
 			smp_hw_index[i] = i;
 	}
 #endif
-
-	/* 32 bits SMP can't NAP */
-	if (!machine_is_compatible("MacRISC4"))
-		powersave_nap = 0;
 }
 
 static int __init smp_core99_probe(void)

Re: [PATCH] powerpc: enable NAP only on cpus who support it to avoid memory corruption

[Benjamin Herrenschmidt]

On Sat, 2006-03-11 at 22:58 +0100, Olaf Hering wrote:
> commit 51d3082fe6e55aecfa17113dbe98077c749f724c enabled NAP unconditinally
> on all powermacs. Early G3 cpus can not use it, the result is memory corruption.
> 
> Only enable powersave_nap in one place: probe_motherboard()
> ppc32 gets nap if the cpu supports it
> ppc32 smp gets no nap
> ppc64 gets nap unconditionally

CONFIG_SMP is certainly not the way to do it though... I wonder how we
got that wrong, I'll have a look.

Ben.


> ---
>  arch/powerpc/platforms/powermac/feature.c |    8 +++++++-
>  arch/powerpc/platforms/powermac/setup.c   |    4 ----
>  arch/powerpc/platforms/powermac/smp.c     |    4 ----
>  3 files changed, 7 insertions(+), 9 deletions(-)
> 
> Index: linux-2.6.16-rc5-olh/arch/powerpc/platforms/powermac/feature.c
> ===================================================================
> --- linux-2.6.16-rc5-olh.orig/arch/powerpc/platforms/powermac/feature.c
> +++ linux-2.6.16-rc5-olh/arch/powerpc/platforms/powermac/feature.c
> @@ -2513,8 +2513,11 @@ found:
>  		/* Nap mode not supported if flush-on-lock property is present */
>  		if (get_property(np, "flush-on-lock", NULL))
>  			break;
> +
> +#ifndef CONFIG_SMP
> +		/* 32 bits SMP can't NAP */
>  		powersave_nap = 1;
> -		printk(KERN_INFO "Processor NAP mode on idle enabled.\n");
> +#endif
>  		break;
>  	}
>  
> @@ -2526,6 +2529,9 @@ found:
>  #ifdef CONFIG_POWER4
>  	powersave_nap = 1;
>  #endif
> +	if (powersave_nap)
> +		printk(KERN_INFO "Using native/NAP idle loop\n");
> +
>  	/* Check for "mobile" machine */
>  	if (model && (strncmp(model, "PowerBook", 9) == 0
>  		   || strncmp(model, "iBook", 5) == 0))
> Index: linux-2.6.16-rc5-olh/arch/powerpc/platforms/powermac/setup.c
> ===================================================================
> --- linux-2.6.16-rc5-olh.orig/arch/powerpc/platforms/powermac/setup.c
> +++ linux-2.6.16-rc5-olh/arch/powerpc/platforms/powermac/setup.c
> @@ -621,10 +621,6 @@ static void __init pmac_init_early(void)
>  	/* Probe motherboard chipset */
>  	pmac_feature_init();
>  
> -	/* We can NAP */
> -	powersave_nap = 1;
> -	printk(KERN_INFO "Using native/NAP idle loop\n");
> -
>  	/* Initialize debug stuff */
>  	udbg_scc_init(!!strstr(cmd_line, "sccdbg"));
>  	udbg_adb_init(!!strstr(cmd_line, "btextdbg"));
> Index: linux-2.6.16-rc5-olh/arch/powerpc/platforms/powermac/smp.c
> ===================================================================
> --- linux-2.6.16-rc5-olh.orig/arch/powerpc/platforms/powermac/smp.c
> +++ linux-2.6.16-rc5-olh/arch/powerpc/platforms/powermac/smp.c
> @@ -739,10 +739,6 @@ static void __init smp_core99_setup(int 
>  			smp_hw_index[i] = i;
>  	}
>  #endif
> -
> -	/* 32 bits SMP can't NAP */
> -	if (!machine_is_compatible("MacRISC4"))
> -		powersave_nap = 0;
>  }
>  
>  static int __init smp_core99_probe(void)
> -
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Re: [PATCH] powerpc: enable NAP only on cpus who support it to avoid memory corruption

[Benjamin Herrenschmidt]

On Sat, 2006-03-11 at 22:58 +0100, Olaf Hering wrote:
> commit 51d3082fe6e55aecfa17113dbe98077c749f724c enabled NAP unconditinally
> on all powermacs. Early G3 cpus can not use it, the result is memory corruption.

Ok, here is what I think is a proper fix: Just remove the code from
setup.c since feature.c will already set powersave_nap when needed.

Can you test asap please ? If it fixes the problem for you, I'll send
the patch to Linus/Andrew with hopes that it will make it in 2.6.16 

---

This patch fixes incorrect setting of powersave_nap to 1 on all
PowerMac's potentially causing memory corruption on some models. This
bug was introuced by me during the 32/64 bits merge.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

Index: linux-work/arch/powerpc/platforms/powermac/setup.c
===================================================================
--- linux-work.orig/arch/powerpc/platforms/powermac/setup.c	2006-02-13 14:10:43.000000000 +1100
+++ linux-work/arch/powerpc/platforms/powermac/setup.c	2006-03-12 10:47:39.000000000 +1100
@@ -621,10 +621,6 @@
 	/* Probe motherboard chipset */
 	pmac_feature_init();
 
-	/* We can NAP */
-	powersave_nap = 1;
-	printk(KERN_INFO "Using native/NAP idle loop\n");
-
 	/* Initialize debug stuff */
 	udbg_scc_init(!!strstr(cmd_line, "sccdbg"));
 	udbg_adb_init(!!strstr(cmd_line, "btextdbg"));
Index: linux-work/arch/powerpc/platforms/powermac/feature.c
===================================================================
--- linux-work.orig/arch/powerpc/platforms/powermac/feature.c	2006-03-01 11:48:27.000000000 +1100
+++ linux-work/arch/powerpc/platforms/powermac/feature.c	2006-03-12 10:51:31.000000000 +1100
@@ -2491,9 +2491,7 @@
 			pmac_mb.model_id = PMAC_TYPE_COMET;
 		iounmap(mach_id_ptr);
 	}
-#endif /* CONFIG_POWER4 */
 
-#ifdef CONFIG_6xx
 	/* Set default value of powersave_nap on machines that support it.
 	 * It appears that uninorth rev 3 has a problem with it, we don't
 	 * enable it on those. In theory, the flush-on-lock property is
@@ -2522,10 +2520,11 @@
 	 * NAP mode
 	 */
 	powersave_lowspeed = 1;
-#endif /* CONFIG_6xx */
-#ifdef CONFIG_POWER4
+
+#else /* CONFIG_POWER4 */
 	powersave_nap = 1;
-#endif
+#endif  /* CONFIG_POWER4 */
+
 	/* Check for "mobile" machine */
 	if (model && (strncmp(model, "PowerBook", 9) == 0
 		   || strncmp(model, "iBook", 5) == 0))

Re: [PATCH] powerpc: enable NAP only on cpus who support it to avoid memory corruption

[Olaf Hering]

 On Sun, Mar 12, Benjamin Herrenschmidt wrote:

> On Sat, 2006-03-11 at 22:58 +0100, Olaf Hering wrote:
> > commit 51d3082fe6e55aecfa17113dbe98077c749f724c enabled NAP unconditinally
> > on all powermacs. Early G3 cpus can not use it, the result is memory corruption.
> 
> Ok, here is what I think is a proper fix: Just remove the code from
> setup.c since feature.c will already set powersave_nap when needed.
> 
> Can you test asap please ? If it fixes the problem for you, I'll send
> the patch to Linus/Andrew with hopes that it will make it in 2.6.16 

Yes, this helps.