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Re: [ARM] EABI and the default to short enums

On 02/15/2012 07:07 AM, Ralf Corsepius wrote:
On 02/14/2012 06:51 PM, Ian Lance Taylor wrote:
Sebastian Huber<> writes:

On 02/14/2012 04:05 PM, Ian Lance Taylor wrote:
Sebastian Huber<> writes:
I would recommend that RTEMS change to the ARM EABI if possible. That
is the current standard ABI on ARM platforms.
That's what Sebastian is trying to do.

Yes, exactly.

It's true that the ARM
EABI is different from the previous ABIs in some respect. I believe
that would mean using ARM_ABI_AAPCS.

I mean the ABI described in "Procedure Call Standard for the ARM Architecture" document number "ARM IHI 0042D, current through ABI release 2.08". In GCC this is ARM_ABI_AAPCS and ARM_ABI_AAPCS_LINUX?

However, if you want to retain GNU/Linux compatibility, then using ARM_ABI_AAPCS_LINUX is likely to be correct.
So you would recommend RTEMS to throw away ARM_ABI_AAPCS and to use
ARM_ABI_AAPCS_LINUX, which as far as I see is a Linux-specific/proprietaty
deviation from EABI?

To me, this seems "hacking" - I am actually leaning towards considering the
issues Sebastian mentions to be portability bugs in the non-GCC components he
faces this issue with.

This is not hacking. It is making a choice between two alternatives described in the document issued by ARM. See also section 7.1.3 "Enumerated Types"

For RTEMS it is surely not the worst choice to use the Linux variant of the EABI since a lot of software is developed for and tested with it.

But I am not an ARM expert.
Neither am I.

Yes, this is also my problem.

Sebastian Huber, embedded brains GmbH

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