Re: [PATCH] nommu: Enable the strict alignment (CR_A) bit only ifARCH < v6
From: Uwe Kleine-König
Date: Wed Dec 05 2012 - 14:51:43 EST
On Mon, Dec 03, 2012 at 05:46:17PM +0000, Will Deacon wrote:
> On Mon, Dec 03, 2012 at 05:25:53PM +0000, Russell King - ARM Linux wrote:
> > On Mon, Dec 03, 2012 at 05:44:11PM +0100, Armando Visconti wrote:
> > > On 11/29/2012 12:04 PM, Armando VISCONTI wrote:
> > >> 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<armando.visconti@xxxxxx>
> > >> ---
> > >> 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.
> 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.
> I think Uwe also requires some of the stuff there for his M3 port.
I didn't check more context than available in the patch and I also
didn't double-check the M3-docs, but AFAIK the M3 doesn't have a cp15
and I noopt this code out.
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | http://www.pengutronix.de/ |
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