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[Brian Hawley]

Brian Hawley
Luminex Software, Inc.
1-951-781-4100 x112
www.luminex.com



	  Original Message  	


From: newlib@sourceware.org
Sent: September 30, 2020 3:46 AM
To: alex.coplan@arm.com
Reply-to: Richard.Earnshaw@arm.com
Cc: newlib@sourceware.org
Subject: Re: [PATCH] libgloss/aarch64: Add support for Armv8-R AArch64


On 29/09/2020 17:27, Alex Coplan via Newlib wrote:
> Hi Richard,
>
> On 29/09/2020 15:06, Richard Earnshaw (lists) wrote:
>> 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.
>
> Good catch. Thanks for the review.
>
>>
>> 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.
>
> Sounds sensible. Is the revised patch (attached) OK?
>
> Thanks,
> Alex
>

Pushed.  I've used the following as the commit message (note that newlib
doesn't use ChangeLog files anymore).

    libgloss: aarch64: Add support for Armv8-R AArch64

    This patch adds support for Armv8-R AArch64.

    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.  So build a different flavour of the
    startup code to support that.

    We also add a specs file that uses this alternative startup code which
    can be used with Armv8-R AArch64 models.

R.