512b will be register size, execution will be like Zen4 on platforms that don't need full speed.
This is useful (unlike quite a few other replies above).
I think you are confusing 2 things:
- instruction support
- implementation of those instructions
Mandate that AVX 10.2 supports 512-bit wide means that it has to support 512-bit wide instructions.
Which implies that all: 128, 256 and 512bit wide instructions are supported.
As far as implementation, it is up to the CPU makers. Zen 5 desktop and server is full 512 wide while Zen 5 mobile and Zen 4 were 256 bit wide.
I believe I have the confusion figured out. Both of these replies got me researching in the right direction.
So here is how it appears to work.
First, AVX10.2 isn't the same as AVX512. In other words, a compiler that ONLY supported AVX10.2 would run in fall back mode on Zen 5 NOT AVX512.
Second, AVX10.2 requires 32 x 512b registers period.
Third, execution path is determined by the hardware support, but utilizes the same compiled code. Execution path can be 128b, 256b, or 512b.
Fourth, there does appear to be additional instructions that do new things above and beyond AVX512 in AVX10.2, but not that much. Mostly, this is exactly what it appears to be. It's a way for Intel to create an instruction set that works across multiple core types to avoid OS scheduling problems .... or to make these operations even possible on a hybrid architecture like ARL. I am not sure if AMD will ever adopt this or not as I am not certain it benefits them AT THIS TIME. Reguardless, AVX512 will continue to be supported especially in DC where it is of the most use.
That's how I have it figured. Now, thanks to those that actually helped.