[PATCH] ARM: PJ4: allow building in Thumb-2 mode

Gregory CLEMENT gregory.clement at free-electrons.com
Mon Nov 24 11:01:43 PST 2014

On 24/11/2014 18:48, Ard Biesheuvel wrote:
> On 24 November 2014 at 18:36, Gregory CLEMENT
> <gregory.clement at free-electrons.com> wrote:
>> Hi Arnd,
>> On 24/11/2014 18:17, Arnd Bergmann wrote:
>>> On Monday 24 November 2014 16:34:47 Ard Biesheuvel wrote:
>>>> On 24 November 2014 at 16:29, Arnd Bergmann <arnd at arndb.de> wrote:
>>>>> On Monday 24 November 2014 12:56:40 Ard Biesheuvel wrote:
>>>>>> Two files that get included when building the multi_v7_defconfig target
>>>>>> fail to build when selecting THUMB2_KERNEL for this configuration.
>>>>>> In both cases, we can just build the file as ARM code, as none of its
>>>>>> symbols are exported to modules, so there are no interworking concerns.
>>>>>> In the iwmmxt.S case, add ENDPROC() declarations so the symbols are
>>>>>> annotated as functions, resulting in the linker to emit the appropriate
>>>>>> mode switches.
>>>>>> Signed-off-by: Ard Biesheuvel <ard.biesheuvel at linaro.org>
>>>>> Ah, very nice. I tried this before, but my version didn't actually
>>>>> work, presumably because I didn't know about the ENDPROC() stuff.
>>>>> Have you tested this on a machine that has IWMMXT enabled?
>>>> No, I don't have access to such a machine, unfortunately.
>>> Adding a few mvebu folks to Cc, maybe one of them can test your patch.
>> Actually even it is a feature of the PJ4 machine non of the mvebu machines
>> currently use it. I only see this configuration enabled for the pxa family.
>> So I think you would have more feedback with the pxa maintainers/owners.
> Are you saying PJ4 should be dropped from 'default' here?

Not at all. I didn't find it in the configuration file, but I didn't realized
it was because of this "default y".

Sorry for the noise.

> config IWMMXT
>         bool "Enable iWMMXt support"
>         depends on CPU_XSCALE || CPU_XSC3 || CPU_MOHAWK || CPU_PJ4 || CPU_PJ4B
>         default y if PXA27x || PXA3xx || ARCH_MMP || CPU_PJ4 || CPU_PJ4B

Gregory Clement, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.

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