hololens: intel or qualcomm?

[rory753]

With intel pulling their resources from their phone atom processor division, and HP choosing to use a arm based phone as opposed to a intel based phone, I have to wonder, why didn't hololens use a arm based processor instead of x86 or x64? the chipsets seem like they would be more suited to this kind of application.

I have no answer, i'm just throwing this out there...

 

[grahamf]

...because Windows on ARM was a fiasco, and Microsoft wants to make absolutely sure it's dead easy to bring your apps to it? Look what happened to the RT tablets.

 

[a5cent]

How well W8 era RT tablets fared in the market and the reasons they failed (which had nothing to do with ARM) just aren't relevant to the question.

IMHO you should first state why you think the ARM instruction set would be more suited. I don't think it matters at all, at least not in terms of technical capabilities.

My guesses: HoloLens is based on Windows IoT which expects DirectX support. Intel does better on that front (e.g. drivers) than ARM based chip designers, and there is little to gain by bringing an ARM based solution up to the same level. Intel also stacks up to 1GB of VRAM onto the die which saves space. Lastly, the HPU connects via a PCIe bus to the SoC, and ARM based solutions rarely support a PCIe bus.

 

[grahamf]

How well W8 era RT tablets fared in the market and the reasons they failed (which had nothing to do with ARM) just aren't relevant to the question.



IMHO you should first state why you think the ARM instruction set would be more suited. I don't think it matters at all, at least not in terms of technical capabilities.



My guesses: HoloLens is based on Windows IoT which expects DirectX support. Intel does better on that front than ARM based chip designers, and there is little to gain by bringing an ARM based solution up to the same level. Intel also stacks up to 1GB of VRAM onto the die which saves space. Lastly, the HPU connects via a PCIe bus to the SoC, and ARM based solutions rarely support a PCIe bus.

ARM and RT are perfectly relevant. And then you go on to explain why.

The whole reason why Windows RT bombed was because users couldn't run their apps or connect to their printers. Microsoft realizes that the Hololens HAS to be a full and proper computer. microsoft's whole thing is that your app will run on a PC, laptop, tablet, smartphone, and even Xbox and Hololens easily. If it ran ARM then it would be stuck with the same lowest common denominators that Windows phone has. If Continuum on Windows phone is successful then Microsoft might reconsider arm, but in the meantime it's not worth it.

 

[a5cent]

ARM and RT are perfectly relevant. And then you go on to explain why.

ARM is basically an instruction set. The things I mentioned have nothing to do with the instruction set.


I mentioned GPU and PCIe support. There is absolutely no reason MS couldn't integrate PCIe 3.0 x16 and, say, an AMD based GPU with an ARM based CPU. The question asked by the OP is why didn't they? IMHO there is just no reason to, because the ARM instruction set doesn't offer us anything uniquely useful to Hololens. Neither does x86 IMHO.

Microsoft realizes that the Hololens HAS to be a full and proper computer.

Ehm.. no. Hololens runs Windows 10 IoT. That's definitely not what you'd consider to be a full/proper computer.

 

[grahamf]

ARM is basically an instruction set. The things I mentioned have nothing to do with the instruction set.


I mentioned GPU and PCIe support. There is absolutely no reason MS couldn't integrate PCIe 3.0 x16 and, say, an AMD based GPU with an ARM based CPU. The question asked by the OP is why didn't they? IMHO there is just no reason to, because the ARM instruction set doesn't offer us anything uniquely useful to Hololens. Neither does x86 IMHO.


Ehm.. no. Hololens runs Windows 10 IoT. That's definitely not what you'd consider to be a full/proper computer.

It can run bona fide Photoshop through project Centennial. it's a PC.

 

[ian masiyandima]

intel

 

[a5cent]

It can run bona fide Photoshop through project Centennial. it's a PC.

I'm not sure, but I suspect you are claiming that project Centennial allows us to easily run any Win32 software (like Photoshop) on Windows IoT, which is incorrect. It doesn't. Centennial doesn't make Win32 software run on any platform it couldn't run on to begin with. Not W10M, not W10IoT.

Like I said... IoT is not a "full" PC.

Centennial just makes Win32 software distributable through the Windows Store (to devices running full W10).

 

[grahamf]

I'm not sure, but I suspect you are claiming that project Centennial allows us to easily run any Win32 software (like Photoshop) on Windows IoT, which is incorrect. It doesn't. Centennial doesn't make Win32 software run on any platform it couldn't run on to begin with. Not W10M, not W10IoT.

Like I said... IoT is not a "full" PC.

Centennial just makes Win32 software distributable through the Windows Store (to devices running full W10).

Which Hololens is.

 

[a5cent]

^ I have no idea what you're trying to say.

 

[grahamf]

^ I have no idea what you're trying to say.

Microsoft is not taking any unnecessary risks inn the push to change the world. Using a mobile platform then trying to cater to developers working on desktop systems would be a risk. They want people like NASA developing for this thing, not Zyinga. NASA and all the other big hitters would want to port their code already made for x86, not have to rewrite everything to ARM.

 

[a5cent]

Do you have anything at all to back that up with? Nothing I've read even hints at that. Why not? Because Hololens is exclusively UWP and doesn't run Win32 desktop software! Just like W10M and W10 IoT.

I think you're confused by the fact that it just happens to have an Intel CPU, which you incorrectly assume to automatically imply Win32 compatibility. However, neither the Intel CPU nor project Centennial gets Hololens anywhere close to running Win32 desktop software! For that it would require Win32, which it intentionally lacks.

If you are correct, finding at least one article claiming Win32 /desktop software compatibility or showing it running said software should be trivial. You can't.

Lastly, you also misunderstand what makes it necessary to port software. These days x86 vs ARM is almost irrelevant in that regard. That job is handled automatically by compilers and runtime environments. That's also why the exact same store app can run on Intel or ARM devices. It's no longer 1990. What does cause porting problems is heavy use of unsupported APIs, and that is why software using the Win32 API won't run on Hololens. It's not supported.

 

[grahamf]

You realize that UWP is built on Win32 right? The whole point of UWP is to a) containerize apps so they don't shove dlls all over the place or **** with the registry and b) provide a consistent interface that can scale from desktops to tablets and even hololens and Xbox easily, but programming is still the same as a traditional program. All they have to do is take their existing back end code and code a compliant UI and directory access, not that hard to do.

Windows on ARM does, however, require a lot more low level programming because it does not have the same API access as Windows x86.


*EDIT* it seems there are rumors that Microsoft intended to switch Windows Phone to x86 before Intel dropped their mobile chip plans, so Microsoft may be intending to go full x86. I'm not going to chase them down to validate their authenticity.

 

[a5cent]

You realize that UWP is built on Win32 right?

Nope. That was true a long time ago but it isn't anymore. Architecturally both Win32 and the UWP sit at the same level above OneCore and neither is dependent on the other.

There is a subset of Win32 APIs that can be called by UWP apps. MS has a list of them somewhere on their site. Compared to the entire Win32 API surface it's very limited however. MS deemed that capability important to support scenarios that the UWP doesn't yet support itself, but that doesn't mean the UWP is based on Win32. You could rip out almost all of Win32 and the UWP environment and apps would continue to work just fine. In fact, that's pretty much what W10M is.

Unfortunately, you're still confused about the role/difference between CPU architectures an APIs. The idea that Windows on ARM requires "a lot more low level programming" is also quite ridiculous. I've developed for Windows on ARM and I can tell you that was no more "low-level" than the UWP is today. In fact, the UWP is just an evolved and re-branded version of WinRT (the API used by developers wanting to target Windows on ARM), so if we sweat the details they are pretty much the same thing.

I doubt we'll make much progress here so I'll leave it at that.

 

[rory753]

Nope. That was true a long time ago but it isn't anymore. Architecturally both Win32 and the UWP sit at the same level above OneCore and neither is dependent on the other.

first things first, thanks for the info on this. I left this thread for 5 months, came back, and whoa, alot of good information.

second, who cares about supporting win32 apps on hololens? the entire interface and thought of computing is completely different from sitting infront of a screen, typing, and then expecting a printer to provide an output. I understand there are legacy issues, but this isn't a phone, where people who buy should be expecting photoshop. people who buy this should be expecting something like "sculptureshop". i'm not using $3000 augmented or virtual reality to watch a 2 dimensional thing.

but getting back to arm versus x86, wouldn't it be cheaper/easier to manufacture a arm based device which would provide the benefit? It seems analogous to inventing an imaginary iphone that supported mac programs, then saying don't worry about developing for it since all those mac programs work on it...

 

[a5cent]

second, who cares about supporting win32 apps on hololens? the entire interface and thought of computing is completely different from sitting infront of a screen, typing, and then expecting a printer to provide an output. I understand there are legacy issues, but this isn't a phone, where people who buy should be expecting photoshop. people who buy this should be expecting something like "sculptureshop". i'm not using $3000 augmented or virtual reality to watch a 2 dimensional thing.

Agreed. I just used the Hololens for the first time last week. I can't imagine how using it with Win32 software could be anything other than extremely frustrating. As you can see, some people do think that Win32 compatibility is part of what MS is offering here. It isn't. After having used Hololens I'd say that's a good thing.

but getting back to arm versus x86, wouldn't it be cheaper/easier to manufacture a arm based device which would provide the benefit? It seems analogous to inventing an imaginary iphone that supported mac programs, then saying don't worry about developing for it since all those mac programs work on it...

What benefit, specifically, are you referring to?

 

[rory753]

What benefit, specifically, are you referring to?

qualcomm processors have better radios and better gpu's then the atoms that are in the hololens. it feels like it would be a better starting point for a mobile wearable then to start with an atom processor...

 

[a5cent]

Okay, you aren't framing your question correctly. Your question has almost nothing to do with x86 vs ARM. Those are CPU instruction sets. They are unrelated to the GPU, radios, or any other particular non-CPU subsystem.

What you are actually asking about is a comparison between two particular series of SoC (system-on-chip). Specifically, the Atom Cherry Trail SoC and likely the Qualcomm Snapdragon 810 (the best Qualcomm SoC available when Hololens was released). That 's important because you are interested in all the components that make up the SoC and those components can vary from one SoC to the next, no matter what instruction set the integrated CPU employs.

So, Hololens uses WiFi. Nothing else. AFAIK all modern SoCs are pretty much identical in that regard. All the other wireless stacks (cellular, etc), where some ARM based solutions may have advantages, just don't matter for Hololens. A draw.

I'm not up-to-date on GPU performance of modern Atom and Snapdragon chips, but last week I was told by a Hololens dev that the graphics subsystem is currently limited to models of about 30'000 polygons. If that's true, then the GPU is also pretty much irrelevant. Any half decent GPU can handle models of that complexity. Also a draw, at least for now.

I can see the GPU becoming an issue if the polygon limit is removed somewhere down the road. On the other hand, MS is apparently working on a way to render the graphics remotely and just send the rendered images to the headset over WiFi, in which case the Hololens wouldn't need a GPU at all.

So, even after re-framing the question, I still can't think of anything that would make me view either SoC as having a notable advantage. At least for the moment. I wouldn't go so far as to say there is none. For example, MS designed a separate chip to handle visual processing. If that chip is integrated into the system over a PCI interface (just a guess on my part), then an Intel based solution is the obvious choice. I'm not aware of any ARM based solution that integrates a PCI interface.

Most of what makes Hololens what it is resides in the custom built processor and MS' software. The SoC itself seems rather unimportant in comparison. At least that is my current take on it.