Re: [v2,4/6] ARM: drop no-thumb-interwork in EABI mode

From: Stefan Agner
Date: Tue Jun 12 2018 - 13:27:36 EST


On 12.06.2018 19:19, Guenter Roeck wrote:
> On Sun, Mar 25, 2018 at 08:09:57PM +0200, Stefan Agner wrote:
>> According to GCC documentation -m(no-)thumb-interwork is
>> meaningless in AAPCS configurations. Also clang does not
>
> It appears that this is only correct for recent versions of gcc.
>
> With gcc 4.9.2, this patch causes the qemu collie emulation
> to fail with collie_defconfig+CONFIG_AEABI.

Hm, interesting. However, even 4.9.0 claims this option is meaningless
when using AAPCS configurations:
https://gcc.gnu.org/onlinedocs/gcc-4.9.0/gcc/ARM-Options.html#ARM-Options

>
> qemu-system-arm: Trying to execute code outside RAM or ROM at 0x02000000
> This usually means one of the following happened:
> ...
>
> With gcc 7.3.0, the emulation works as expected. Reverting the patch
> fixes the problem with gcc 4.9.2. Not that it matters much to me - I can
> and will switch to gcc 7.3.0 for my testing - but effectively this means
> that older versions of gcc are no longer supported for all configurations.
>
> Maybe $(call cc-option,-mno-thumb-interwork,) would have been safer ?

I used to have call cc-option in place, but I removed that when I
realized that gcc claims it is meaningless with AAPCS configurations.

--
Stefan

>
> Guenter
>
>> support the flag:
>> clang-5.0: error: unknown argument: '-mno-thumb-interwork'
>>
>> Just drop -mno-thumb-interwork in AEABI configuration.
>>
>> Signed-off-by: Stefan Agner <stefan@xxxxxxxx>
>> ---
>> arch/arm/Makefile | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/arch/arm/Makefile b/arch/arm/Makefile
>> index e83f5161fdd8..e9e3fde3c657 100644
>> --- a/arch/arm/Makefile
>> +++ b/arch/arm/Makefile
>> @@ -106,7 +106,7 @@ tune-$(CONFIG_CPU_V6K) =$(call cc-option,-mtune=arm1136j-s,-mtune=strongarm)
>> tune-y := $(tune-y)
>>
>> ifeq ($(CONFIG_AEABI),y)
>> -CFLAGS_ABI :=-mabi=aapcs-linux -mno-thumb-interwork -mfpu=vfp
>> +CFLAGS_ABI :=-mabi=aapcs-linux -mfpu=vfp
>> else
>> CFLAGS_ABI :=$(call cc-option,-mapcs-32,-mabi=apcs-gnu) $(call cc-option,-mno-thumb-interwork,)
>> endif