Re:Intel Discloses Lakefield CPUs Specifications
by dmitrygr on Wednesday June 10, 2020 @02:50PM
(#23480657)
If this is going to be anything like how arm did it, intel most likely upgraded the atom CPUs to support all the instructions of the big core, probably just very slowly. For example, you will find that the lowly Cortex-A7 supports virtualization extensions. Why? Because it was paired with big cores that supported them.
The only way to make big.LITTLE work and allow task migration between them is to have them support the same instruction set exactly. So, I suspect that that is why AVX512 was removed from the big core here, and I suspect the atom cores aren't exactly garden variety either. They probably support most other extensions of modern x86 CPUs, at a slow speed.
For example, AVX2 can be microcoded by running multiple pieces of the data through the ALU, one at a time.
The only way to make big.LITTLE work and allow task migration between them is to have them support the same instruction set exactly. So, I suspect that that is why AVX512 was removed from the big core here, and I suspect the atom cores aren't exactly garden variety either. They probably support most other extensions of modern x86 CPUs, at a slow speed. For example, AVX2 can be microcoded by running multiple pieces of the data through the ALU, one at a time.