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Why Apple Went 64-Bit With the iPhone 5s
Hugh Pickens DOT Com writes "Adrian Kingsley-Hughes says it's not just because Apple likes bragging about being first and because a 64-bit processor sounds cooler than 32-bits that Apple used the 64-bit A7 chip in the new iPhone 5s. A shift from a 32-bit processor to a 64-bit part paves the way for iPhones to be fitted out with 4GB+ of RAM down the line, but more importantly the move brings iOS and OS X apps much closer. The architecture for 64-bit apps on iOS will be almost identical to the architecture for OS X apps, making it easy to create a common code base that runs in both operating systems. 'Apple has slowly been bringing iOS-like features to Mac OS for years now: think of Launchpad and Gatekeeper,' writes Sascha Segan. 'The ultimate prize, of course, would be to bring the million-plus iOS apps to Macs. Apple could do that with an ARM-compatible virtual machine on Mac hardware, but it would want the VM, the OS and the associated apps to play nicely in the much larger memory space available on Macs. That means moving the whole system over to 64 bit.' By unifying iOS and Mac OS with Xcode developer tools in a 64-bit space, Apple could once again leap ahead of Microsoft and Google, says Segan. Microsoft hasn't yet been able to leverage its desktop strengths to achieve success as a mobile OS. The 64-bit chips for Android devices aren't ready, and neither is Android itself."
Several journalists have made this mistake, such as the drivel posted here: Trusted Reviews
They seem to think that the register size being equal means that software written for them is somehow much more similar. In reality the CPUs and the software they run are no closer to each other than before. The main benefit of this move to the latest ARM CPU design is ironically much the same as the advantage brought by x86_64 - more registers are now available and some floating point operations are more efficient. This will translate into a small performance increase but it won't be night and day.
Apple's move to the 64-bit ARM platform isn't about compatibility with OSX, support for over 4G of ram (per process, the 32-bit ARM processor can handle 1TB of RAM already) or for performance reasons (the additional memory load will almost undoubtedly overpower the slight increases in the 64-bit ARM processing improvements).
If you read through ARM's announcement of it's 64-bit platform a large portion of it is dedicated to the new security layer allowing for better segmentation between applications and a more in-depth security layer in between the segments. This will allow Apple to sit a hypervisor below the kernel and protect the system from "attacks" and if we can get through the hypervisor there is an additional ARM security layer before you can run in the top processor privilege layer.
64-bit ARM isn't about anything other than preventing jailbreaking.
He doesn't understand. Here's a picture and bio of the guy who wrote the article. He's mainly focused on hardware, as in books about assembling PCs from parts, so it looks like his career path was PC-repair-guy-to-author. He's obviously never written any substantial cross-platform software. He was looking through new iPhone documentation (which is right here), and he saw a line that mentions it's easy to write code that is shared on iOS and OSX. He thought that was something new, he didn't realize that it's already easy, and has nothing to do with 64bit.
"First they came for the slanderers and i said nothing."
I did. The whole thing is nonsense. You don't have to enforce a single architecture to have common code. Neither do you need to have a virtual machine running the same bit-ness as the host operating system. This is just the usual kind of cluelessness that comes from a community that is proud of being stupid.
Yeah. 64-bit BS.
A Pirate and a Puritan look the same on a balance sheet.
You are absolutely right. The whole summary doesn't make any sense at all... first of all, the Macs run 32-bit applications just fine. Second, if you can emulate a 64-bit ARM, you can emulate a 32-bit ARM. Third, phone apps would suck on a laptop or desktop.
I suspect they went to 64-bit for the simple reason that it is the direction ARM is going. This processor design is likely to show up in their lower-end products for years after it leaves their flagship device, and the sooner they go to 64-bit, the sooner they can depreciate the 32-bit stuff. Unless the 64-bit chip cost significantly more to design, produce, or unless it has a significant performance penalty, there is no reason to delay making it.
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Seriously, has no one here heard of Physical Address Extension?
Yes. Let us never speak of it again.
If God forks the Universe every time you roll a die, he'd better have a damned good memory.
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Get thee glass eyes, and, like a scurvy politician, seem to see things thou dost not.--King Lear