[fedora-arm] armv7hl requirements

[Peter Robinson]

On Thu, May 5, 2011 at 4:50 AM, Jon Masters <jonathan at jonmasters.org> wrote:
> On Thu, 2011-05-05 at 08:23 +1200, Michael Hope wrote:
>
>> >> *). ARM VFP3 hardware floating point (h)
>> >> *). ARM NEON Architecture
>> >> *). Thumb2 interworking
>>
>> I don't think you have to anything explicit here.  Thumb-2 and ARM
>> code interoperate just fine.
>>
>> >> *). Your suggestion here?
>>
>> *) Hard float.  Never worse than soft float, sometimes much better.
>
> Note that hard float is implied by VFPv3, and by the subject being
> "armv7hl". The intention is to use the aapcs-vfp binding but the only
> real debate is whether to use the D16/32 option. That comes down to
> whether we want to focus on really great A15 plus or be more inclusive
> of various minimal ARMv7 systems that are already out there today.
>
> Perhaps we need a matrix of known capabilities in v7 hardware. I guess
> that's another wiki page I should create, starting with my Beagle, Panda
> and Efika systems, but a pointer to AC100 specs would be cool (I found
> various reviews on it, and wow it's pricey compared to e.g. Efika) :)

The AC100 is based on the nvidia tegra 250. Its also used in a lot of
the Android 3 tablets and also devices like the ASUS transformer and
slider [1]. At the moment it seems to be the chip of choice for a lot
of the latest ARM consumer devices. Also it seems there's a Marvell
Dove processor that also uses D16.

While I like the idea of optimising for the A15 processor all
literature I've seen on it indicates that the first silicon won't be
available until sometime in 2012 and devices running them until 2013
although I would like to be proved wrong. Also it appears that the A15
will be using VFPv4 [2] so I suspect to make best use of that we'll
need to compile for it and therefore be different again to A8/A9.

Peter

[1] http://en.wikipedia.org/wiki/Nvidia_Tegra
[2] http://www.arm.com/products/processors/cortex-a/cortex-a15.php
[3] http://wiki.debian.org/ArmHardFloatPort/VfpComparison