[Mesa-dev] [PATCH 00/13] Implement INTEL_shader_atomic_float_minmax

[Axel Davy]

On 23/06/2018 07:03, Ian Romanick wrote:
> I initially started implementing support for NV_shader_atomic_float.  I
> had misunderstood the hardware specs, and Intel hardware cannot actually
> do that extension.  It does have some floating-point atomic support, so
> I decided to create an extension based on what the hardware actually can
> do.  I discussed this with some guys at AMD and NVIDIA, and it seems
> nobody else can do these things.

Hi,


Older AMD SI chips had the functionality, as can be seen here:

https://developer.amd.com/wordpress/media/2012/12/AMD_Southern_Islands_Instruction_Set_Architecture.pdf


It features BUFFER_ATOMIC_FMIN, BUFFER_ATOMIC_FCMPSWAP and 
BUFFER_ATOMIC_FMAX.

The feature seems to have been dropped with later iterations of GCN.


Reading the spec of intel broadwell, there are some sections mentioning 
atomic float add,

https://01.org/sites/default/files/documentation/intel-gfx-prm-osrc-bdw-vol07-3d_media_gpgpu_3.pdf


But there is no mention of it for Skylake. Maybe it was supported, but 
dropped ?


Yours,

Axel Davy