NEON support

Enabling NEON

CONFIG_NEON is required to enable NEON support in the Linux kernel * You must also have CONFIG_VFPv3 to save/restore the VFPv3-D32 context (which is the NEON context) * CONFIG_NEON additionally adds understanding of the NEON coprocessor numbers and is required to handle the 'lazy context save' implemented by the ARM Linux kernel on single-processor systems

Note on certain cores there are additional configuration requirements:

Cortex-A8

L1NEON? bit in the Auxiliary Control register - this controls whether NEON can allocate lines in the L1 cache on a miss. With this set to 0, there is a possible NEON performance improvement for very large datasets where access sequences do not benefit from L1 caching. With this set to 1, there is a NEON performance boost for small datasets which do fit in L1 cache.

Cortex-A9

There is no additional configuration for NEON on Cortex-A9, as NEON data is always allocated into L1 as with integer load/store data.

-- IanR - 08 Jun 2009