Apple A7 is now 64-bit

[Eug]

Yeah... it just seems really weird to put a 64 bit processor in a phone that only has 2 GB of memory with no way to add memory.

We still don't know for sure it has 2 GB of memory, but I'm hopeful for that. iFixit, please buy an iPhone 5S and give us the tear down that week! If it's 2 GB, I'm buying one for sure.

Maybe they are just getting the developers ready for 64 bit... I don't know.

That's what I was thinking.

They're developing their own chips, and 64-bit probably seemed ripe for them for the A7, so they just went for it. How's that for a n00b assessment?

Furthermore, if they're already at 2 GB this generation with the iPhone (although as I said I'm not sure about that), it's quite possible they would jump to 4 GB with the iPad 5 in 2013 (very unlikely) or iPad 6 in 2014 (possible). That's only a year away. It's not as if they introduced 64-bit in 2009. At that time, it would have been way too premature. Adding 64-bit now gives all the 3rd party developers a chance to think about 64-bit over the coming year, and tells them Apple has a clear plan for 64-bit too. It also gives Apple itself something real in 64-bit to play with. I think the 32 to 64 bit message is a lot more muddled on the Android side.

Yeah I know the reasoning in the last paragraph is soft, but the fact is that Apple went 64-bit early and we're trying to find reasons for it.

The other possibility is that maybe it's not an existing iDevice, but an entirely new one that will use A7 as well.

 

[DA CPU WIZARD]

Does the iPhone 5S even have 2 GB RAM? I'm wondering if it still might only have 1 GB. I hope not, for future proofing reasons.

To put it another way, due to RAM overhead, must a 64-bit phone require 2 GB, if the 32-bit little brothers (iPhone 5 and likely 5C) have only 1 GB? By the sounds of the discussion here, it seems like 2 GB might be recommended for a 64-bit iOS, even if 32-bit iOS 7 runs perfectly well on the previous 1 GB flagship iPhone 5.

BTW, for reference, the A6 is 95 mm2, so the A7 is only a 7% increase in physical size, but the A6 was on a 32 nm process.

Can you really think of any other logical reasons for Apple to switch to 64-bit if its not to prepare the App Store for when 64-bit is a necessity, and for minor performance gains in certain apps?

And for the record, Apple is staying with Intel for their laptops and desktops. ARM can't really compete with something like Haswell.

 

[TerryMathews]

Can you really think of any other logical reasons for Apple to switch to 64-bit if its not to prepare the App Store for when 64-bit is a necessity, and for minor performance gains in certain apps?

And for the record, Apple is staying with Intel for their laptops and desktops. ARM can't really compete with something like Haswell.

I asked about XIP yesterday (and was ridiculed for it) but it would be a simple way to pick up some free performance. Even if just IOS was XIP on some linear flash...

 

[Khato]

Indeed, there's little question that Apple included 64 bit support to lay the groundwork.

Sure they could have waited another generation... but by doing so now they get another marketing point for A7. If they'd waited until the next generation they wouldn't get to be the "world's first 64 bit smartphone SoC". You have to remember that the majority of consumers have no clue that a 64 bit processor isn't necessary for their smartphone - they'll just think that it's better.

 

[DA CPU WIZARD]

Just think... In 2-3 years we will be looking at iPads with something AROUND 4GB of memory. By then, (presumably) the majority of the popular apps will be compatible with 32-bit and 64-bit SoCs. When the A9 equipped iPad 7 is released, consumers will have a host of optimized apps that outclass competing 32-bit based tablets.

Furthermore, you have to remember that Intel is releasing their 64-bit Atom SoC. If this gains traction, Intel based tablets and phones will have a competitive advantage over Apple if Apple did NOT just go 64-bit.

Just think of how much trouble something like the Android Samsung Tab 4 10.1 with a 64-bit Intel Atom processor WITH 64-bit optimized apps would be for Apple.

Now, imagine the average consumer's reaction to Apple advertisments in a few years when Apple can show off games and apps that are optimized for 64-bit and can fully utilize 4GB+ of RAM. Now THAT'S a selling point from a non-techy consumer's standpoint.

FINALLY, iOS 7 and all that it entails was built for a 64-bit SoC. All future iOS updates will be built for 64-bit SoCs. Also, all future Apple SoCs will be built in 64-bit. This means that there will be consistency between the iPhone 5S, and the iPhone 6... Along with the iPhone 5S, and the iPad 5, etc. This makes it simple across the board for Apple, developers, and techies like us who have to keep track of this stuff! ;-)

 

[venkman]

Thread reminds me of 2003, A64 all over again.

"Who needs more than 4GB of ram pfft gtfo!"

Better to have and not need than need and not have. :thumbsup:

I feel old

2003 was a decade ago and you can certainly say you still do not need more than 4 GB Ram to be a basic computer user. I had 3GB up until a year ago and bumping it up to 12 only impacted the highest performing of apps.

 

[Mopetar]

Ok so 64 bits allows you to address >4GB of memory efficiently and when including memory-mapped devices, that threshold sits at somewhere below 4 GB. I still don't get why Apple would want/need to introduce potentially redundant transistors in todays products in order to "be ready" or "force developers in the right directions". Having the power of vertical integration that Apple has, they could simply force all AppStore apps to be compiled for 32/64 bits, and introduce 64-bit hw whenever it was really needed?

First, this change probably has nothing to do with memory limits. The ARM Cortex-A15 has 40-bit addressable memory, so by the time other manufacturers are running into the memory wall, the SoCs that are being put into phones will mitigate it, even if they're not 64-bit.

My guess is that Apple has some plans for the future with its software and it wants to make sure that when it reaches that point, it will have older hardware that's still capable of running the update.

There might be some good stuff in the A64 instruction set, and from a quick glance at wikipedia, it looks like it increases the number of SIMD registers as well, so it's going to have a lot more processing power in some cases.

 

[Eug]

2003 was a decade ago and you can certainly say you still do not need more than 4 GB Ram to be a basic computer user. I had 3GB up until a year ago and bumping it up to 12 only impacted the highest performing of apps.

Well, the problem with my nettop is that I put in 4 GB and it turns out it only supports 3.x GB. I feel ripped off, esp. since 256 MB of that is eaten up by the GPU.

At least with 64-bit, it wouldn't be 3.x GB. It'd actually be 4 GB... which I agree is OK for basic mainstream usage... for now.

 

[Exophase]

I asked about XIP yesterday (and was ridiculed for it) but it would be a simple way to pick up some free performance. Even if just IOS was XIP on some linear flash...

I'm sorry, what? Asking if you were from a GBA homebrew community wasn't ridicule. I was just surprised someone was using the term

I also answered your question, it's not an option. I'm sorry if my explanation doesn't make sense to you.

 

[Nothingness]

What does XIP mean? Execute in place? I wouldn't want to run soft from flash directly...

 

[TerryMathews]

I'm sorry, what? Asking if you were from a GBA homebrew community wasn't ridicule. I was just surprised someone was using the term

I also answered your question, it's not an option. I'm sorry if my explanation doesn't make sense to you.

Its an option if they load the OS on linear flash as opposed to EMMC.

Maybe your issue is that you're assuming that you are the smartest person in the room? Many devices besides the GBA used XIP.

What does XIP mean? Execute in place? I wouldn't want to run soft from flash directly...

Why? There's no loading or unloading and it drastically reduces memory footprint as the entirety of the OS is accessible.

 

[Rakehellion]

I would say the two biggest factors of importance for OS updates are:

1) RAM size.
2) CPU speed.

There's no mobile OS that's sucking up 1GB of memory.

 

[Rakehellion]

Yes it will. A 64 bit app needs to use 64 bit pointers which are twice the size of 32 bit pointers. Depends on the programme but you are looking at say 25% more memory needed to run exactly the same programme compiled for 64 bit not 32 bit.

99% of an app's data is graphics, not code, so that's irrelevant.

 

[Rakehellion]

Not that it really matters as no one will write 64 bit phone apps as there's no need and they'd only work on the 5S, they'll all be 32 bit for years to come

You can compile binaries that run in both 32-bit and 64-bit natively.

 

[Eug]

There's no mobile OS that's sucking up 1GB of memory.

I wasn't just talking about the OS alone. With Android and lots of apps loaded, 1 GB can be a limitation... hence the proliferation of 2 GB Android devices.

 

[Nothingness]

Why? There's no loading or unloading and it drastically reduces memory footprint as the entirety of the OS is accessible.

Code isn't executed in sequence and you don't want to pay flash latency each time you miss. The cost would be terrible

 

[DA CPU WIZARD]

99% of an app's data is graphics, not code, so that's irrelevant.

Good point.

 

[Exophase]

Its an option if they load the OS on linear flash as opposed to EMMC.

Linear flash is NOR flash. NOR flash is much more expensive per bit than NAND flash. Which is why everyone uses NAND flash if they need to minimize cost for large storage (in far more than just eMMCs or SSDs - most standalone flash chips are NAND, SD cards are NAND, etc).

NAND flash can't be addressed directly so XIP is not a real option.

Maybe your issue is that you're assuming that you are the smartest person in the room? Many devices besides the GBA used XIP.

Asking if you're from a GBA homebrew community is in no way making myself sound like the smartest person in the room. I hadn't heard someone use the term outside of there before, that doesn't mean that I thought it was the only place it was ever used, I was just CURIOUS. It was a totally innocent question (with a smiley after it no less). I don't know what you're getting so bent out of shape and being such a jerk over, it was never my intention to ridicule you or make you feel less intelligent than me.

 

[TerryMathews]

Linear flash is NOR flash. NOR flash is much more expensive per bit than NAND flash. Which is why everyone uses NAND flash if they need to minimize cost for large storage (in far more than just eMMCs or SSDs - most standalone flash chips are NAND, SD cards are NAND, etc).

NAND flash can't be addressed directly so XIP is not a real option.



Asking if you're from a GBA homebrew community is in no way making myself sound like the smartest person in the room. I hadn't heard someone use the term outside of there before, that doesn't mean that I thought it was the only place it was ever used, I was just CURIOUS. It was a totally innocent question (with a smiley after it no less). I don't know what you're getting so bent out of shape and being such a jerk over, it was never my intention to ridicule you or make you feel less intelligent than me.

Fair enough. That isn't the way it came across, to me, but the internet as you know makes it difficult to judge the meaning behind words sometimes. :beer:

I've written code for XIP devices (and no, not GameBoys. ), so I'm very familiar with the limitations and advantages. All that said, I think we all know this is a hyopthetical discussion. Apple isn't doing this for any technical advantage it offers this generation. They are doing to to recapture the Atari Jaguar's marketing plan "It's twice as powerful!"

Will it grow into it? Sure. But since the device won't take receive any advantage from 64 bit processing, it is unfortunate to see Apple force it before it's needed. With their total vertical integration and walled garden software library, there's no reason why they couldn't have forced apps to be 64-bit ready and waited until a device actually needed a 64 bit OS to roll it out.

 

[Eug]

I'm pretty sure Apple will limit iOS to 64-bit devices at some point in the not too distant future. That means at some future cutoff point (3 years?), iOS 10 will likely support the iPhone 5S, but not the iPhone 5.

 

[Exophase]

Fair enough. That isn't the way it came across, to me, but the internet as you know makes it difficult to judge the meaning behind words sometimes. :beer:

Thanks for understanding. Sorry if I was overly reactionary in that last one.

I've written code for XIP devices (and no, not GameBoys. ), so I'm very familiar with the limitations and advantages.

The XIP thing is actually kind of funny now that I think more about it, since it's very normal for microcontroller applications to run code straight from flash >_> I guess the context I've seen it in was ucLinux on GBA, where it was mentioned since XIP isn't really normal for Linux but that was the only way they could get anything running with so little RAM.

All that said, I think we all know this is a hyopthetical discussion. Apple isn't doing this for any technical advantage it offers this generation. They are doing to to recapture the Atari Jaguar's marketing plan "It's twice as powerful!"

Will it grow into it? Sure. But since the device won't take receive any advantage from 64 bit processing, it is unfortunate to see Apple force it before it's needed. With their total vertical integration and walled garden software library, there's no reason why they couldn't have forced apps to be 64-bit ready and waited until a device actually needed a 64 bit OS to roll it out.

I'm sure the marketing is part of it - they're definitely marketing it already, and Apple is selective with what it markets - but I can also see why it saves their OS developers some grief, and that lets them worry more about some other stuff. Assuming iPhone 5S will have 2GB of RAM, just managing that in a typical kernel space partitioning would already mean having to special case it.

Developers submit compiled apps to Apple, and apps are free to use both intrinsics and actual hand-written assembly (and some do, you can see plenty of questions about using NEON this way on Stack Overflow, for instance). Forcing developers to make those 64-bit friendly before there was even a real platform to test that on would be impractical. In the mean time, I don't really see them forcing it on anyone, and it remains to be seen how much they'll even encourage devs to use it. If you have to support both 32-bit and 64-bit at the same time it's hard to actual design the app to benefit from 64-bit in any way (and I'm not aware that Apple will use a fat binary format to begin with), and I'm sure Apple isn't going to be that enthusiastic about developers only supporting the very newest model on day one.

 

[Zor Prime]

Future-proofing. May as well do it now, versus later.

 

[tipoo]

Or they're on their way to ditching Intel entirely. Apple has an ARM architectural license so they could conceivably design their own high performance ARM chip and put them in MacBooks.

Going from PowerPC to x86 made sense because Windows computers used x86, and Intel provided higher performance per watt than IBM. It's /possible/ I guess that Apple could make a CPU better than Intel, but then they'd be dropping all the compatibility. I just don't see it. iOS uses ARM because most mobile devices do.

 

[Eug]

Somebody at Apple is teasing with GFXBench:

Both the iPhone 5 and the iPhone 5S in the comparison are running iOS 7. Onscreen resolution is 1136x640.

FWIW, my 1280x720 RAZR HD (Jelly Bean 4.1) with Qualcomm MSM8960 Snapdragon Dual-core 1.5 GHz Krait Adreno 225 gets 2551 frames (23 fps) for the Onscreen test, but the bench crashed for the Offscreen test with a "Out of video mem" error message the first time. The second time after a fresh reboot it gave me 1548 (14 fps), after a crash too. After the reboot the onscreen was very similar, at 2552 (23).

My freshly rebooted 1280x800 Nexus 7 2012 (Jelly Bean 4.3) Tegra 3 is 1642 (15) Onscreen and 1105 (9.8) Offscreen, with no crashes.

Summary:

Egypt HD 2.5 Onscreen
iPhone 5S - 5991 frames (53.0 fps)
iPhone 5 - 4643 frames (41.1 fps)
RAZR HD - 2552 frames (23 fps)
Nexus 7 - 1642 frames (15 fps)

Egypt HD 2.5 Offscreen
iPhone 5S - 6332 frames (56.0 fps)
iPhone 5 - 3370 frames (29.8 fps)
RAZR HD - 1548 frames (14 fps) - crashes
Nexus 7 - 1105frames (9.8 fps)

 

[tipoo]

I find myself thinking that 64 bit support will be Apples next support cuttoff point, probably not with iOS8 but maybe 9. Just like when OSX went 64 bit, 32 bit machines were supported for some time, then they decided everything had to be 64 bit and support was dropped.

Now that GPU, it was listed only as "A7 GPU" in support docs (can't find the link now), while others were called SGX whatever GPUs. I wonder, is this their first in-house part? They were gobbling up GPU engineers. The driver number however seems consistent with SGX.