[PATCH] nommu: Enable the strict alignment (CR_A) bit only if ARCH < v6

On 12/03/2012 06:46 PM, Will Deacon wrote:

On Mon, Dec 03, 2012 at 05:25:53PM +0000, Russell King - ARM Linux wrote:

quoted

On Mon, Dec 03, 2012 at 05:44:11PM +0100, Armando Visconti wrote:

quoted

On 11/29/2012 12:04 PM, Armando VISCONTI wrote:

quoted

This patch keeps disabled the strict alignment CP15 bit for
all armv6 and armv7 processor without the mmu. This behaviour
is now same as in the mmu case.

Signed-off-by: Armando Visconti<redacted>
---
   arch/arm/kernel/head-nommu.S |    2 +-
   1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/arch/arm/kernel/head-nommu.S b/arch/arm/kernel/head-nommu.S
index 278cfc1..2c228a0 100644
--- a/arch/arm/kernel/head-nommu.S
+++ b/arch/arm/kernel/head-nommu.S

@@ -68,7 +68,7 @@ __after_proc_init:
   	 * CP15 system control register value returned in r0 from
   	 * the CPU init function.
   	 */
-#ifdef CONFIG_ALIGNMENT_TRAP
+#if defined(CONFIG_ALIGNMENT_TRAP)&&   __LINUX_ARM_ARCH__<   6
   	orr	r0, r0, #CR_A
   #else
   	bic	r0, r0, #CR_A

Any feedback on this simple patch?

Well, it brings the nommu version into line with the mmu version, so
it's sensible.  Please put it in the patch system, thanks.

Done!

In which case, I'll definitely dust-off the patches to prevent unaligned
accesses to strongly-ordered memory because that results in good ol'
UNPREDICTABLE behaviour.

Yes, we definetely need them.

Thx,
Arm