Hi Geert,
On 06/06/12 06:57, Geert Uytterhoeven wrote:
On Wed, May 30, 2012 at 4:04 PM, Philippe De Muyter<phdm@xxxxxxxxx> wrote:
On Wed, May 30, 2012 at 01:20:02PM +0200, Geert Uytterhoeven wrote:
On Wed, May 30, 2012 at 12:22 PM, Philippe De Muyter<phdm@xxxxxxxxx> wrote:
On Tue, May 29, 2012 at 11:33:36PM +0200, Geert Uytterhoeven wrote:
Signed-off-by: Geert Uytterhoeven<geert@xxxxxxxxxxxxxx>
---
Do we also want
select HAVE_EFFICIENT_UNALIGNED_ACCESS if (!COLDFIRE&& !M68000)
Sorry, I did not follow what happened to unaligned accesses, but
CPU32 family (at least 68340) crashes on unaligned accesses.
We don't seem to have CONFIG_M68340 in arch/m68k/Kconfig.cpu?
I have a local port here (but based on an ancient linux kernel, 2.6.2 IIRC)
But Freescale's website confirms both 68340 and 68360 are CPU32.
arch/m68k/include/asm/unaligned.h assumes CPU32 (CONFIG_MCPU32)
can do unaligned accesses:
That's not true. Accessing a 16- or 32-bit word at an odd address
with a 68340 generates an Address Error Exception. I remember
discovering a bug in the ppp kernel code because of that.
#if defined(CONFIG_COLDFIRE) || defined(CONFIG_M68000)
#include<linux/unaligned/be_struct.h>
#include<linux/unaligned/le_byteshift.h>
#include<linux/unaligned/generic.h>
#define get_unaligned __get_unaligned_be
#define put_unaligned __put_unaligned_be
#else
/*
* The m68k can do unaligned accesses itself.
*/
#include<linux/unaligned/access_ok.h>
#include<linux/unaligned/generic.h>
#define get_unaligned __get_unaligned_be
#define put_unaligned __put_unaligned_be
#endif
Is this wrong?
I can't tell from reading just the lines above, but I think one should add
"|| defined(CONFIG_MCPU32)" at the end of the if condition.
Greg?
If more CPUs cannot handle unaligned accesses, I propose to add
CONFIG_CPU_HAS_NO_UNALIGNED.
Yes, looks like that should have a "|| defined(CONFIG_CPU32)".
(According to the CPU32 reference manual words and long words must
be aligned on word boundaries.)
I think something like CONFIG_CPU_HAS_NO_UNALIGNED makes sense.
I also think that the Coldfire 5272 can do unaligned accesses, but I
cannot test that at the moment.
According to the MCF5272 User Manual, "it supports misaligned data
accesses ...". So it looks like it does.
Having a CONFIG_CPU_HAS_NO_UNALIGNED looks like a really good solution
then. We need to be able select it as required on individual CPU types.
Regards
Greg
------------------------------------------------------------------------
Greg Ungerer -- Principal Engineer EMAIL: gerg@xxxxxxxxxxxx
SnapGear Group, McAfee PHONE: +61 7 3435 2888
8 Gardner Close FAX: +61 7 3217 5323
Milton, QLD, 4064, Australia WEB: http://www.SnapGear.com
--
To unsubscribe from this list: send the line "unsubscribe linux-m68k" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
