[Buildroot] target options for Cortex A8/A9
thomas.petazzoni at free-electrons.com
Sun Feb 1 20:48:46 UTC 2015
Dear Sagaert Johan,
On Sun, 1 Feb 2015 20:51:48 +0100, Sagaert Johan wrote:
> I am using imx53, this cpu has according to the datasheet an NEON SIMD media accelerator
> and an VFPv3 co-processor.
> So I would assume the same selections options as for the A9.
> I was wondering what makes the target options different for A8 vs A9.
> I would think that for the imx53 it sould be the same as for the A9,
> That is an NEON SIMD extension and a vfpv3 floating point engine.
> Please clarify, it is a bit confusing to me.
> For the A8 I can select vfpv3 OR Neon, but not vfpv3 WITH NEON extension.
On Cortex-A8, NEON is mandatory. On Cortex-A9, NEON is optional. So
when you activate Cortex-A8, Buildroot knows NEON is available. When
you activate Cortex-A9, since NEON is optional, you have to tell
Buildroot if NEON is actually available or not.
Note the difference between BR2_ARM_CPU_HAS_NEON for Cortex-A8 and
BR2_ARM_CPU_MAYBE_HAS_NEON for Cortex-A9.
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering
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