Compiling a kernel for armv5 + armv6

Compiling a kernel for armv5 + armv6

[Sascha Hauer]

Doing so currently breaks with:

arch/arm/kernel/entry-armv.S: Assembler messages:
arch/arm/kernel/entry-armv.S:196: Error: selected processor does not support `strex r1,r2,[sp]'
arch/arm/kernel/entry-armv.S:228: Error: selected processor does not support `strex r1,r2,[sp]'
arch/arm/kernel/entry-armv.S:286: Error: selected processor does not support `strex r1,r2,[sp]'
arch/arm/kernel/entry-armv.S:323: Error: selected processor does not support `strex r1,r2,[sp]'

These are used in svc_exit and restore_user_regs.

Is there a way to fix this or do we have to live with this?

Sascha

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Compiling a kernel for armv5 + armv6

[saeed bishara]

On Thu, Mar 3, 2011 at 3:20 PM, Sascha Hauer <s.hauer@pengutronix.de> wrote:
> Doing so currently breaks with:
>
> arch/arm/kernel/entry-armv.S: Assembler messages:
> arch/arm/kernel/entry-armv.S:196: Error: selected processor does not support `strex r1,r2,[sp]'
> arch/arm/kernel/entry-armv.S:228: Error: selected processor does not support `strex r1,r2,[sp]'
> arch/arm/kernel/entry-armv.S:286: Error: selected processor does not support `strex r1,r2,[sp]'
> arch/arm/kernel/entry-armv.S:323: Error: selected processor does not support `strex r1,r2,[sp]'
>
> These are used in svc_exit and restore_user_regs.
>
> Is there a way to fix this or do we have to live with this?
try to add this line to the Makefile
 AFLAGS_entry-armv.o      :=-Wa,-march=armv6k
>
> Sascha
>
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Compiling a kernel for armv5 + armv6

[Sascha Hauer]

On Thu, Mar 03, 2011 at 03:50:26PM +0200, saeed bishara wrote:
> On Thu, Mar 3, 2011 at 3:20 PM, Sascha Hauer <s.hauer@pengutronix.de> wrote:
> > Doing so currently breaks with:
> >
> > arch/arm/kernel/entry-armv.S: Assembler messages:
> > arch/arm/kernel/entry-armv.S:196: Error: selected processor does not support `strex r1,r2,[sp]'
> > arch/arm/kernel/entry-armv.S:228: Error: selected processor does not support `strex r1,r2,[sp]'
> > arch/arm/kernel/entry-armv.S:286: Error: selected processor does not support `strex r1,r2,[sp]'
> > arch/arm/kernel/entry-armv.S:323: Error: selected processor does not support `strex r1,r2,[sp]'
> >
> > These are used in svc_exit and restore_user_regs.
> >
> > Is there a way to fix this or do we have to live with this?
> try to add this line to the Makefile
>  AFLAGS_entry-armv.o      :=-Wa,-march=armv6k

This surely keeps the compiler happy, but I doubt the result will work
on an armv5 processor.

Sascha


-- 
Pengutronix e.K.                           |                             |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |

Compiling a kernel for armv5 + armv6

[Russell King - ARM Linux]

On Thu, Mar 03, 2011 at 02:20:57PM +0100, Sascha Hauer wrote:
> Doing so currently breaks with:
> 
> arch/arm/kernel/entry-armv.S: Assembler messages:
> arch/arm/kernel/entry-armv.S:196: Error: selected processor does not support `strex r1,r2,[sp]'
> arch/arm/kernel/entry-armv.S:228: Error: selected processor does not support `strex r1,r2,[sp]'
> arch/arm/kernel/entry-armv.S:286: Error: selected processor does not support `strex r1,r2,[sp]'
> arch/arm/kernel/entry-armv.S:323: Error: selected processor does not support `strex r1,r2,[sp]'
> 
> These are used in svc_exit and restore_user_regs.
> 
> Is there a way to fix this or do we have to live with this?

As I've mentioned before, ARMv3-ARMv5 is fine.  ARMv6-ARMv7 is fine (with
patches).  ARMv5->ARMv6 is too big an architecture change to live together.

Compiling the above file for ARMv6 doesn't fix the problem because then
you'll be executing ARMv6 instructions on ARMv5 CPUs, which will fault.
Omitting those instructions makes ARMv6 behaviour unpredictable - as it
means no barriers could be used, no exclusive operations, etc.

Certainly ARMv5 + ARMv6MP is totally out of the question.