My answers inline. I was confused as hell just a month back :)

On 23 March 2017 at 06:28, Francois Ozog <[email protected]> wrote:

> The more I dig the less I understand ;-)
>
> Let me ask a few questions:
>
> - in the future, when selling 32 bit silicon, which architecture version
> will it be ARMv7 or ARMv8 ?
>

What you are referring to is ISA version, not architecture. AArch32 and
AArch64 are architectures. ARMv8 also supports AArch32 (i.e. AArch32 with
ARMv8 ISA)

- is the target solution will be running ALL in 32 bits? (boot in 32 bits,
> Linux 32 bits, 32 bits apps)?
> - or is the target solution will be hybrid (64 bits Linux and some 32 bits
> apps).
>

The target solution could be Hybrid. Linux could be 64b, the applications
could be 32b. It is my understanding that everything 32b is also possible
using AArch32.


> When I read "AArch64 was designed to remove known implementation
> challenges of AArch32 cores" on http://infocenter.arm.com/
> help/index.jsp?topic=/com.arm.doc.dai0490a/ar01s01.html
> I wonder if stating we support AArch32 is a good idea...
>
> So what is the best way to describe what we want?
> -  ARMv8    LP64 or ILP32 ?
> - AArch64  LP64 or ILP32 ?
> - LP64 or ILP32?
>
> I think the best way to say is 'we support AArch64 and AArch32'.


> FF
>
>
> On 23 March 2017 at 04:57, Honnappa Nagarahalli <
> [email protected]> wrote:
>
>> Hi Bill / Matt and others,
>>             What I was trying to say in our discussion is that, the
>> ODP-Cloud code should not be pointer heavy.
>>
>> Please take a look at this video from BUD17:
>> http://connect.linaro.org/resource/bud17/bud17-101/ (unfortunately
>> there are no slides, I am trying to get them). This talks about the
>> performance of the 32b application on AArch64. One of the
>> applications, has huge performance improvement while running in 32b
>> mode (ILP32 in this particular case) on AArch64 (when compared to the
>> same application compiled for 64b mode running on AArch64 i.e. in 64b
>> compilation it performed very poorly). My understanding is that this
>> particular application is a pointer chasing application. Other
>> applications which are not pointer heavy, do not have this behavior.
>>
>> So, we need to make sure ODP-Cloud is not pointer heavy and does not
>> force the application to be pointer heavy, to get good performance out
>> of 64b systems.
>>
>> Thank you,
>> Honnappa
>>
>
>
>
> --
> [image: Linaro] <http://www.linaro.org/>
> François-Frédéric Ozog | *Director Linaro Networking Group*
> T: +33.67221.6485
> [email protected] | Skype: ffozog
>
>

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