When Apple announced the new batch of iDevices last year with its shiny new A7 ARM chip, much was made of its 64-bit architecture. Apple was happy to tout the A7 as the first mobile chip with 64-bit support, which is a nice marketing angle. While the practical advantages are limited right now, Samsung was quick to point out that it too will produce 64-bit devices in the not too distant future.
Well, here we are on the verge of the Galaxy S5 and there’s barely been a peep about 64-bit support. That’s fine, though. Samsung doesn’t really need to move to 64-bit just yet. More than that, it simply wouldn’t be practical.
A 64-bit ARM-compatible CPU would have to be based on the ARMv8 instruction set. The Cortex-A15 cores that do the heavy lifting in Samsung’s Exynos parts right now are ARMv7, as are almost all other ARM CPUs. Samsung makes its own ARM packages, or systems-on-a-chip (SoC), but the architecture is licensed from ARM.
To continue doing what it has always done, Samsung would have to wait for ARM to get the updated Cortex-A50 series CPUs ready for licensing, and that’s probably still months away. It wouldn’t be smart to wait on that core.
So could Samsung be working on its own custom 64-bit CPU core like Apple or Nvidia have done? Again, this wouldn’t be a great use of Samsung’s energies. It takes years and tens of millions in ARM instruction set licensing fees to design custom CPU cores.
Nvidia, which has a ton of semiconductor expertise on staff, has taken several years to build the 64-bit Denver core, and that’s not reaching devices until the end of 2014.
No one has indicated that Samsung bought the necessary licenses to build a custom 64-bit core at all.
If Samsung was to throw resources at the problem and possibly even delay the Galaxy S5 debut to get a workable 64-bit core from ARM, what does it gain? Well, it would definitely be able to say it has the first 64-bit Android device, and that’s pretty much it. The core of Android is still 32-bit, so any benefit from having a 64-bit CPU would be nil on the software side.
The ARMv8 instruction set does include some architectural improvements and better power efficiency, but when we’re talking about Samsung, the company is just as happy to slap a bigger battery into its 5in to 6in phones and call it a day. Even if Samsung wanted to make some sort of software optimisation for 64-bit, it would still have plenty of devices on 32-bit.
Because Samsung straddles so many markets, it has different versions of its flagship. The HSPA variant of the GS5 will probably run Exynos, but the LTE versions sold in the UK, US and elsewhere will likely still be on Snapdragon. Rewriting software to take advantage of 64-bit on only some versions of the phone doesn’t make much sense.
At the end of the day, the cost-benefit analysis still comes out in favour of using a 32-bit Exynos for one more generation. The potential marketing opportunity is really the only reason to consider going to the hassle of making the Galaxy S5 64-bit. I wouldn’t necessarily put it past Samsung, but the Galaxy S5 simply doesn’t need to compete with Apple on that front.