Re: [PATCH] libgloss/aarch64: Add support for Armv8-R AArch64

["Richard Earnshaw (lists)" <Richard.Earnshaw@arm.com>]

On 18/09/2020 15:43, Alex Coplan wrote:
> Hello,
> 
> This patch adds support for Armv8-R AArch64. We update the AArch64 CPU
> boot code to work on Armv8-R if __ARM_ARCH_PROFILE is set to 'R'.
> Armv8-R AArch64 has no EL3, so we don't set vbar_el3, and adjust the
> code to set up the MPU for Armv8-R.
> 
> We also add a specs file for use with Armv8-R AArch64 models.
> 
> Testing:
>  * Ran AArch64 GCC testsuite using --with-arch=armv8-r together with the
>    new specs file and boot code in an Armv8-R AArch64 model.
>  * Ran newlib testsuite, no regressions.
> 
> OK for master?
> 
> Thanks,
> Alex
> 
> ---
> 
> 2020-09-18  Alex Coplan  <alex.coplan@arm.com>
> 
> libgloss/ChangeLog:
> 
> 	* aarch64/Makefile.in: Install new specs file.
> 	* aarch64/cpu-init/Makefile.in: Also build boot code for Armv8-R.
> 	* aarch64/cpu-init/rdimon-aem-el3.S: Add support for Armv8-R.
> 	* aarch64/elf-aem-v8-r.specs: New.
> 

The main problem I see with this is that it assumes that the compiler
being used is *not* configured for a default CPU architecture of
ARMv8-r.  If it is, then the normal rdimon-aem-el3.o file will in fact
become the same as the v8-r version, which is not really what we want.

Perhaps, rather than hacking around the __ARM_ARCH_PROFILE setting you
should just set things up to build the file twice, but with a different
conventional pre-define set each time.

R.