The short story is that AMD didn’t actually announce at their AFDS conference that a Cortex-A5 will be put in to their future CPUs(1). Before you have a minor stroke about AMD dumping x86, or hybrid tablet type work, that likely will not happen. Instead, the A5 will probably be used as a system control and security co-processor.
If you look at the die size of a 40nm AMD Bobcat CPU as used in Brazos, it is around 80mm^2. The A5 core on the same 40nm is <1mm including cache and NEON instructions. See a difference? The A5 is a glorified widget controller, but has some things that AMD lacks, most notably an already accepted security infrastructure and software base.
The deal is about Trustzone, ARM’s VM based security infrastructure. Since Trustzone is pretty much the de facto standard for mobile security and AMD has no similar technology, this deal makes sense. Without Trustzone, AMD would be almost totally locked out of the mobile e-commerce world. An A5 takes almost zero die space, costs pennies, and is pretty much a tried and tested solution. It makes much more sense to slap one on to an x86 die than for AMD to reinvent the wheel. And test that reimplemented wheel. Then convince the carriers and money leeches that it is secure.
So in the end, AMD bought a security and e-commerce solution that has a massive software base, is already accepted by the world at large, and best of all, is cheap. With the FSA/HSA bus infrastructure already in place, it is something between a no-brainer and cut and paste solution addition. And to think people laughed when we said this a year ago. Actually, to be honest, this isn’t a new development, the A5 is already in current AMD CPUs, so if it hasn’t changed your world with current parts, it is unlikely to do so once it is officially revealed.S|A
(1) The ARM Coretex-A5 is in current AMD CPUs, likely both Brazos 2.0 and Trinity. AMD hasn’t officially disclosed which models it is in, but SemiAccurate is confident that it is there.