Re: [PATCH] FreeBSD arm support, EABI.

[Andreas Tobler <andreast-list at fgznet dot ch>]

Hi Kyrill,

On 03.11.14 12:44, Kyrill Tkachov wrote:

> CC'ing arm maintainers and a couple of comments inline.

Thank you!

> On 02/11/14 22:11, Andreas Tobler wrote:
> > Hello all,
> >
> > this is a patch which brings support for arm*-*-freebsd* to trunk.
> > The architectures supported are arm-*-*freebsd*, armv6-*-freebsd* and
> > armv6hf-*-freebsd*.
> > armv6 stands for ARM_ARCH == 6, arm stands for ARM_ARCH < 6.
>
> Why split at ARM_ARCH == 6 ? I see in the patch you define
> TARGET_FREEBSD_ARMv6 but
> only ever use it to define the SUBTARGET_CPU_DEFAULT. In the other arm
> triplets I don't think
> we have architecture-specific identifiers in the arm* parts...

Well, I mentioned it in another response, it was unfortunate from me to 
write the equal sign. What we currently do is the following:

ARM_ARCH >= 6 becomes armv6*-*-freebsd*
ARM_ARCH <= 5 becomes arm-*-freebsd*

So, would you suggest to leave the SUBTARGET_CPU_DEFAULT away?

> > +
> > +#if defined (TARGET_FREEBSD_ARMv6)
> > +#undef  SUBTARGET_CPU_DEFAULT
> > +#define SUBTARGET_CPU_DEFAULT TARGET_CPU_arm1176jzs
> > +#else
> > +#undef  SUBTARGET_CPU_DEFAULT
> > +#define SUBTARGET_CPU_DEFAULT   TARGET_CPU_arm9
> > +#endif
> > +
>
> What about ARMv7? The default CPU there is TARGET_CPU_cortexa8

Would fall under armv6 with the above rule.

> > Index: gcc/config.gcc
> > ===================================================================
> > --- gcc/config.gcc	(revision 217020)
> > +++ gcc/config.gcc	(working copy)
> > @@ -259,7 +259,6 @@
> >       arm*-wince-pe*			\
> >     | arm*-*-ecos-elf			\
> >     | arm*-*-elf				\
> > - | arm*-*-freebsd*			\
> >     | arm*-*-linux*			\
> >     | arm*-*-uclinux*			\
> >     | i[34567]86-go32-*			\
> > @@ -1000,6 +999,27 @@
> >    	extra_options="${extra_options} arm/vxworks.opt"
> >    	tmake_file="${tmake_file} arm/t-arm arm/t-vxworks"
> >    	;;
> > +arm*-*-freebsd*)                # ARM FreeBSD EABI
> > +	tm_file="dbxelf.h elfos.h ${fbsd_tm_file} arm/elf.h"
> > +	case $target in
> > +	arm*b-*-freebsd*)
> > +	    tm_defines="${tm_defines} TARGET_BIG_ENDIAN_DEFAULT=1"
> > +	    ;;
> > +	esac
> > +	tmake_file="${tmake_file} arm/t-arm arm/t-bpabi"
> > +	tm_file="${tm_file} arm/bpabi.h arm/freebsd.h arm/aout.h arm/arm.h"
> > +	case $target in
> > +	armv[67]*-*-freebsd*)
> > +	    tm_defines="${tm_defines} TARGET_FREEBSD_ARMv6=1"
> > +	    ;;
> > +	esac
>
> So you also match armv7*-*-freebsd*. As mentioned above I'm not sure why
> we would want these per-architecture triplets. If we do want to have
> these per-architecture triplets, there is also the ARMv8 AArch32 state
> which is supported in the arm backend and can be identified by ARM_ARCH
> == 8. Do we want to add an armv8*-*-freebsd triplet as well?

Aehm, this is left over from a trial where I tried an 
armv7hf-*-freebsd*. This does not exist yet and I'm not sure if we 
really want that.

Regarding armv8, for the 64-bit there will be another triplet. armv8 
with AArch32 would also fall under armv6 now, but I can not say how it 
would behave, I lack the hardware ;)

Thanks for the feedback.

Andreas