RFR (M): 8036767 PPC64: Support for little endian execution model

[Alexander Smundak]

Ping.

On Wed, Mar 12, 2014 at 4:59 PM, Alexander Smundak <asmundak at google.com> wrote:
> I was concerned by the term 'variant', which might suggest that the applications
> built for PPC64 and PPC64LE are binary compatible. They are not.
>
> On Wed, Mar 12, 2014 at 3:55 PM, David Holmes <david.holmes at oracle.com> wrote:
>> On 12/03/2014 9:19 AM, Alexander Smundak wrote:
>>>
>>> On Tue, Mar 11, 2014 at 3:51 PM, Vladimir Kozlov
>>> <vladimir.kozlov at oracle.com> wrote:
>>>>
>>>> It would only help if you could do cross compilation to have both build
>>>> variants at the same place. Currently you can only build le variant on
>>>> ppc64le machine and vice versa. That is why, I think, David asked if we
>>>> can
>>>> control what variant to build.
>>>
>>> Just to clarify the situation a bit: ppc64le is not a variant of ppc64.
>>> That is,
>>> an application compiled for the little-endian PowerPC64 does not "just
>>> run" on
>>> the big-endian PowerPC64 (albeit OS can have such feature, similar to the
>>> ability of the Linux running on x86_64 CPU to run 32-bit x86
>>> applications).
>>> So ppc64le is a different architecture from ppc64.
>>
>>
>> I disagree with that classification for "architecture" and it seems at odds
>> with the literature which describes the endian-ness selection as a "mode".
>>
>> David
>> -----
>>
>>
>>>> I would like to see the changes based on Volker suggestion. We can
>>>> compare
>>>> them and decide which way to go.
>>>
>>> Volker has the detailed suggestion here:
>>>
>>> http://mail.openjdk.java.net/pipermail/ppc-aix-port-dev/2014-March/001790.html
>>> and it involves additional Make variable and if statements in the
>>> platform makefile
>>>   where they are not supposed to be present.
>>>
>>