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

On Mon, Dec 03, 2012 at 04:44:11PM +0000, Armando Visconti wrote:

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?

Although this is correct, you still need some extra patches to avoid
unaligned accesses to strongly-ordered memory (given that we don't
currently have mainline support for the MPU). Take a look at my nommu/fixes
branch:

  https://git.kernel.org/?p=linux/kernel/git/will/linux.git;a=shortlog;h=refs/heads/nommu/fixes

I'm happy to post some of that if it's useful to you.

Will