ARM GCC machine options for RTEMS 6

Joel Sherrill joel at rtems.org
Fri Jul 3 13:05:07 UTC 2020


On Fri, Jul 3, 2020 at 2:06 AM Sebastian Huber <
sebastian.huber at embedded-brains.de> wrote:

> Hello,
>
> someone from ARM changed the machine options used to build the RTEMS
> multilibs some time ago (I think GCC 8):
>
> arm-rtems6-gcc -print-multi-lib -march=armv4t
> .;
> thumb;@mthumb
> armv5te+fp/hard;@march=armv5te+fp at mfloat-abi=hard
> thumb/armv6-m;@mthumb at march=armv6-m
> thumb/armv7-a;@mthumb at march=armv7-a
> thumb/armv7-r;@mthumb at march=armv7-r
> thumb/cortex-m3;@mthumb at mcpu=cortex-m3
> thumb/cortex-m4+nofp;@mthumb at mcpu=cortex-m4+nofp
> thumb/armv7-a+simd/hard;@mthumb at march=armv7-a+simd at mfloat-abi=hard
> thumb/armv7-r+fp/hard;@mthumb at march=armv7-r+fp at mfloat-abi=hard
> thumb/cortex-m4/hard;@mthumb at mcpu=cortex-m4 at mfloat-abi=hard
> thumb/cortex-m7/hard;@mthumb at mcpu=cortex-m7 at mfloat-abi=hard
> eb/thumb/armv7-r;@mbig-endian at mthumb@march=armv7-r
> eb/thumb/armv7-r+fp/hard;@mbig-endian at mthumb@march=armv7-r+fp at mfloat-abi
> =hard
>
> It seems that our current machine options still map to the right multilib:
>
> arm-rtems6-gcc -print-multi-directory -march=armv7-a -mthumb -mfpu=neon
> -mfloat-abi=hard -mtune=cortex-a9
> thumb/armv7-a+simd/hard
>
> arm-rtems6-gcc -print-multi-directory -mthumb -mcpu=cortex-m4
> -mfpu=fpv4-sp-d16 -mfloat-abi=hard
> thumb/cortex-m4/hard
>
> arm-rtems6-gcc -print-multi-directory -march=armv7-r -mthumb -mbig-endian
> eb/thumb/armv7-r
>
> arm-rtems6-gcc -print-multi-directory -march=armv7-r -mthumb
> -mbig-endian -mfpu=vfpv3-d16 -mfloat-abi=hard
> eb/thumb/armv7-r+fp/hard
>
> Should we change the options to match the ones given in the multilib
> definition or should we keep the current options? If we change the
> options, then we can no longer build with GCC 7.
>

Unless they are going to remove the old options, I would tend to want to
stick
with them.

--joel

>
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