Intel Confronts a Big Mobile Challenge: Native Compatibility

smaxp writes: "Intel has solved the problem of ARM-native incompatibility. But will developers bite? App developers now frequently bypass Android's Dalvik VM for some parts of their apps in favor of the faster native C language. According to Intel, two thirds of the top 2,000 apps in the Google Play Store use natively compiled C code, the same language in which Android, the Dalvik VM, and the Android libraries are mostly written.

The natively compiled apps run faster and more efficiently, but at the cost of compatibility. The compiled code is targeted to a particular processor core's instruction set. In the Android universe, this instruction set is almost always the ARM instruction set. This is a compatibility problem for Intel because its Atom mobile processors use its X86 instruction set."

Comments

Fsck x86

[Anonymous Coward]

I like compatability, but I've had it with x86. Let ARM hog the limelight for a while, no reason it shouldn't have its fifteen minutes. And let x86 die, it's way past its BBE date and has outstayed its welcome by several generations.

Re:Fsck x86

[Anonymous Coward]

This person is likely in their 20s, I am assuming early 20s. With that said, I am in my 30s, somewhat early. My first PC was an 8088 and I've deep dived into every modern processor since then. Even with the debacle that was Windows 7 and 8, I am still going to stand behind x86 as a great architecture that can stand the sands of time.

Scalability: What other architecture has scaled so far that it was completely decimated two competing architectures from the past and the future at the same time. The original 8088/86 was 3mhz, the latest x86 offering is 4ghz.

Popularity: Both Apple and Sun saw the writing on the wall, Sun saw it too late, Apple saw it early (or saw what happened to Sun). They both shifted from a proprietary processor and chipset to a more common and popular platform. Both platforms had specific benefits over x86 until x86 scaled far and beyond what they both offered.

Backwards Compatibilty: I know my x86 processor is still going start in 8-bit mode and I know that I can put it in 16bit mode and run my 1992 applications. But to that extent, x86-64 just extends the instruction set. eg ARM32 does not play on ARM64.

Let's face it. I witnessed Y2K. I witnessed every weak architecture under the sun get wiped out because it had shortcomings. Intel designed the best architecture with x86 and naysayers generally harp because it's "too big". I, for one, plan to teach my children x86 ASM so they understand the basics.. then let them find MIPS or ARM or whatever-fad-arch-is-current so they too can appreciate the design of x86.

Re:Fsck x86

[lagomorpha2]

I, for one, plan to teach my children x86 ASM so they understand the basics.. then let them find MIPS or ARM or whatever-fad-arch-is-current so they too can appreciate the design of x86.

This is just a guess but you don't actually have children yet, do you?

Re:Fsck x86

[Anonymous Coward]

You have no concept. Many companies, including Intel, have tried to move away from x86 - the market won't let them. There is too much software out there written to the x86 architecture to move away from it. You are completely underestimating the market forces behind x86.

Staying with x86 is *not* Intel's choice, of even their desire (they have tried to shift the market off x86). This is where real world forces/issues trump ivory tower technical perspectives.

Re:Fsck x86

[gbjbaanb]

x86 is good in the same way that a modern police baton is good - its still a stick you hit people with, and serves its purpose. But there are better weapons available.

So saying that x86 is great because technology has had to improve to make up for its deficiencies is just stupid. x86 isn't some wonderful architecture, putting 4 cores on a single die isn't anything that x86 made happen that others couldn't do, fabrication techniques that shrunk the die size isn't anything to do with x86 either.

Think that a motorola 68000, way back in the day was better than the old 286s it compared to. Imagine that the 68000 took off instead of the 286 - if MS and IBM had built DOS for 68000 instead of x86... today we'd be in pretty much the same position but with a different chipset. But it would be faster and cheaper and more efficient.

BTW x86 32-bit doesn't run on x86_64 either. The software and chips have emulation routines that allow it to happen. The same as happens with A64 that allows old A32 and T32 instructions to still run on the same chip.

Re:Fsck x86

[dave420]

Windows 7 was not a debacle. ME & Vista, fair enough, but not 7.

Re:Fsck x86

[drinkypoo]

You figured that out...how exactly? It's a RISC, RISCs have historically scaled very, very well.

What does that even mean any more? Visibly-CISC processors are now internally-RISCy (All of them since Am586) and there is actually a benefit to be derived from variable-length instructions and the x86 decoder is a small portion of the modern CPU. But ARM cores have never gotten up into the big, big clock rates because they've never been designed for them, instead targeting efficiency. That's a much easier goal to reach than bigger shinier if you're on a constrained budget, and it certainly has paid off for them now that we care about power budgets, but they're still having trouble scaling.

I'd sure like to hear anything insightful anyone has to say about XScale. It was the fastest ARM implementation of its day, but it was also the most power-hungry, and AFAICT Intel never really managed to scale either performance up or power consumption down after their initial release, and then dropped it. Is that how it played out?

Re:Fsck x86

[aethelrick]

ARM is massively dominant in the embedded and mobile markets. These markets make up a vast quantity of electronics gear. Intel (the X86 pushers) even make ARM chips. ARM is starting to make in-roads into larger devices and encroach on traditional Intel/X86 stomping grounds. ARM have plans for servers and PC's running with their chips. They are low cost, low power and quite good at what they do. Admittedly they won't be replacing your PC gaming rig any time soon, but they're not chasing that market (yet). You are sadly unaware of just what ARM is if you think it's had it's "15 minutes" it's just getting started at the edges of the PC market, it's backed by many vendors and I for one think it'll be around for a while yet. Look at the market share tablets have stolen from the PC, they are mostly ARM powered. Sure netbooks seem a little crusty, and havn't had the uptake their manufacturers were hoping for, but ARM server gear is taking off. Also the IT nippers are playing with ARM with their Arduino and Raspberry Pi gear. I wouldn't count ARM out just yet. Hell, I just replaced my decade-old trusty Linux server at home with a Wandboard Quad running Arch Linux for ARM. Guess what, it works really well, as a Samba, Backup and Email server for the family and I'm not even an ARM enthusiast, it was just MUCH cheaper than a regular Intel or AMD replacement and perfectly up to the task.

Re:Fsck x86

[OneAhead]

First of all, at this point, it is misguided to talk about x86 as an architecture; there is generally little or no architectural overlap between two x86 processors that are a few generation apart. x86 is an instruction set, or even more correct, a family of instruction sets. The distinction is important, especially in the age of complex instruction decoders; a lot of the more complex x86 instructions are internally decoded into smaller pieces, and one could say that the CPU internally runs its own, different instruction set. The fact of supporting a certain instruction set nowadays says almost nothing about the underlying architecture.

So we're talking about an instruction set. One that was conceived in an age where manual coding in machine language was far more common than it is today; the original x86 instruction set was designed to be easy for a human bitpusher to handle, whereas newer instruction sets like ARM are more geared to get the most out of a decent optimizing compiler. What followed for x86 was extension upon extension, and the instruction set is now so byzantine that x86 is a very difficult market to break into; the design complexity of the decoder can probably be overcome, but all the cross-licensing between Intel and AMD cannot. The complex, organically-grown instruction set also leads to some waste of silicon in having to support all those instructions, and waste of performance/energy efficiency in that the instruction set is not designed from the ground up towards efficiency. People on the x86 side make a compelling argument that this has become negligible, but the fact remains that I'm still not seeing any x86 processor getting (unbiased) performance/W scores that are close to common ARM processors.

My first computer contained a Z80, a true 8-bit processor (your claim that x86 has 8-bit mode is false; the lowest common denominator for x86 is the 16-bit 8086, which you're probably confusing with the 8-bit 8080 which is not x86 compatible). More relevantly, I also have experience running scientific workloads on a whole zoo of processors. I have particularly fond memories of the later Alphas, which wiped the floor with everything up until and including the Pentium 4, and were very competitive even against Athlon 64 and Core2 performance-wise (but not price-wise). Repeat after me: x86 has zero inherent architectural advantage!!! The big advantages it has is (1) economies of scale and (2) the higher profits of a mass market that generate more revenue to be pumped into R&D. There hasn't been a kid on the block that could compete on these fronts - not until ARM came around.

While Intel is sitting on an impressive pile of cash and R&D potential, their attempts to match ARM in performance/W are so far unsuccessful when looking at non-biased benchmark results, and ARM has profited from this in establishing a mass market of its own. Things are about to get interesting from here onwards. I can't predict whether x86 or ARM will win. The outcome might be coexistence, with x86 keeping its dominance in the server room, workstation, office and hard-core gaming, and everything else becoming ARM. Whatever the outcome might be, I am firmly rooting for ARM, though. Technically, it's leaner, more rationally designed instruction set that is more frugal with resources (die size, cache & memory usage) and better reflects present-day usage cases. And the fact that it's relatively straightforward for a newcomer to license it and start making chips will bring some healthy competition onto the stage.

Re:Fsck x86

[ezelkow1]

then let them find MIPS or ARM or whatever-fad-arch-is-current so they too can appreciate the design of x86.

Mips and arm as fads? You do realize mips has been around almost as long as x86 has, and is still widely used. People all too often forget that the majority of devices out there are not full fledged computers, they are embedded devices, to which mips and arm own the space. This is exactly why mips is still widely taught in colleges as it is readily accessible, open, and still used in the industry. It also gives a good foundation to build on when looking at other ISAs

Re:Fsck x86

[JohnFen]

Since we're all playing the age card, I'm 50 and have been actively developing software since I was 12 (using punch cards and the ultra-fast and modern paper tape!)

The x86 is a fine architecture, despite its numerous warts. However, so is arm. Each has distinct advantages and disadvantages -- and being able to operate in power-starved situations (such as with smartphones) is one of the main strengths of arm and one of the main weaknesses of x86. If my experiences has taught me anything, it's that there's no such thing as a single approach that works well in every situation. If all you have is a hammer...

"Intel designed the best architecture"

What is "best" depends on what it's used for. There's no such thing as a single architecture that is the "best" in every situation. Arm is hardly the "current fad". It's been around and going strong for a long, long time -- and it's being used in smart phones because it happens to be the best solution for that application currently on the market.

Re:Fsck x86

[Type44Q]

BTW x86 32-bit doesn't run on x86_64 either. The software and chips have emulation routines that allow it to happen.

Unless I'm mistaken, that's completely incorrect.

Re:Fsck x86

[Pepix]

Popularity: Both Apple and Sun saw the writing on the wall, Sun saw it too late, Apple saw it early (or saw what happened to Sun). They both shifted from a proprietary processor and chipset to a more common and popular platform. Both platforms had specific benefits over x86 until x86 scaled far and beyond what they both offered.

Did you mean: 'Apple suffered from a PowerPC processor shortage, while Sun added x86-64 to their lines of workstations and servers'?

Get you facts right: Sun didn't shift to being an x86 shop, and Oracle hasn't, too. In fact, the SPARC architecture is so alive, that is used in some of the Top 500 Supercomputers... as IBM's PowerPC.

Re:Fsck x86

[drinkypoo]

First of all, at this point, it is misguided to talk about x86 as an architecture;

Thank you. I got a raft of shit when I argued that there was no such thing as an x86 instruction set architecture any more just recently, and hasn't been since the Am586 took x86 into RISC-land.

I'm still not seeing any x86 processor getting (unbiased) performance/W scores that are close to common ARM processors.

On the other hand, I'm seeing a pretty massive gap between the high-end in x86 (really, amd64) processors and in ARM processors. This doesn't mean ARM can't be scaled up, but I think it's worth remembering what x86 went through in being scaled up. It didn't happen overnight. It may well be that x86-compatible processors embrace low power consumption before the ARM-compatible processors scale up to the high end.

Re:Fsck x86

[rahvin112]

A typical processor design takes around 4-5 years from concept to production silicon. Intel did not even consider power as a constraint (other than a maximum) until 2008.Haswell was the first ground up design where power was a constraint, but still not a major constraint. With Haswell Intel was within shooting distance of ARM power levels without even compromising computing power.

In about 2010 power consumption became not just a feature, but a required feature in low watt to milliwatt ranges. Intel should have a processor to meet that requirement later this year or early/mid next year. Intel's already preliminarily released some (un-handicapped) atoms that have about 75% of the performance of Haswell and are power competitive with ARM.

Up until a year or two ago when the PC market began to crater Intel wasn't interested in playing in the low power market because margins were atrocious, but with the rise of high margin smartphones and the reality that they will likely replace a significant chunk of the personal PC market they've begun to take the market seriously. Writing them off as unable to play this game because they haven't bothered in the past would be incredibly stupid. They are the largest CPU designer in the world and they have some of the smartest CPU designers in the world working for them, it just takes a while to turn such a big boat. Give it a few more years then come back and talk about x86 being unable to compete.

  I don't know if Intel will succeed but if they put their resources into it they will easily outpace ARM because in the CPU design game it's about design resources and FAB's and Intel has both in spades (in FAB's Intel is one entire process step ahead of everyone else), more than the rest of the ARM market combined and they won't be designing the same thing 50 times. See that's the ARM markets biggest handicap, there are dozens of companies reinventing the wheel over and over again. Intel's biggest handicap is their desire to not eat existing markets and it might be their undoing (a processor with 75% of haswell's power with ARM's power use could likely cannibalize much of their Haswell sales and the tricks to prevent that, ie sales restrictions, will also handicap the processors chances in competing with ARM). IMO if Intel fails at competing with ARM it will only be because they didn't want to cannibalize sales with lower margin parts.

Re:Fsck x86

[maccodemonkey]

x86 is hardly any less proprietary than PowerPC or SPARC. You've got Intel and AMD at the helm. VIA walked the plank ages ago.
Apple ditched PowerPC because Apple's market share was so fucking low that the only company compiling for PowerPC was Adobe. The decision to drop PowerPC had to do with market share and cost, not the architecture itself.

Yes? No? I think this is a misunderstanding of the motivations behind Apple's PowerPC switch. (Source: I wrote PowerPC Mac apps at the time and was in the room at WWDC when Apple announced the switch.)

The PowerPC market was a bit wider than that. Microsoft had Office on PowerPC, Adobe had their suite, and there was a smattering of other apps.

At the time, the future of PowerPC had looked pretty bright. Microsoft's Xbox, Sony's PS3, and Nintendo's Wii were all switching to PowerPC. Within a span of several months, the community was looking at a majority of gaming hardware being PowerPC based. PowerPC was going to be in very high demand, which would mean great things for the Mac PowerPC platform. Far from "the only company compiling for PowerPC was Adobe", Microsoft was buying Power Mac G5 boxes for their dev kits and they were porting Windows to the PowerPC for the Xbox. And in the end, Microsoft, Sony, and Nintendo combined shipped several hundred million units based on the PowerPC (With Nintendo still shipping the Wii U with PowerPC today.)

So why did Apple leave the PowerPC?

At the time, laptop sales were on the rise, but Apple's laptop CPUs were not designed by IBM, they were designed by Motorola. IBM's PowerPC G5 was suitable for the Xbox 360 and desktop machines, but it ran far too hot to go into laptops. This left Motorola with their G4 CPU. And let me tell you, Motorola probably had very smart people working for them, but their execution was incompetent. The G4 had a 133 mhz system bus (which was slow even for the time), and ran very hot (but still cooler than the G5), and worst of all, was much slower than Intel's Pentium M.

Meanwhile the Pentium M was doing very well. It was faster than the G4, more power efficient than the G4, and it actually had a modern chipset and bus. Switching to the Pentium M was a no brainer.

There was speculation that Apple was trying to get IBM to make a mobile G5, but they were never able to get the power consumption down. When Microsoft and Sony entered onto the scene, IBM's interest shifted to getting the PowerPC into larger form factors, and Apple just didn't ship enough units in laptops to balance out the R&D demand that Microsoft and Sony created.

Motorola in the meantime with the G4 just kept sucking. There was a new architecture that was basically a modern architecture for the G4 that did eventually end up shipping, but by then Apple was just done with PowerPC.

Intel provided a stability the AIM (Apple, IBM, Motorola) alliance just didn't provide, with a quality chip. PowerPC did end up scaling, but there simply wasn't the same demand for PowerPC machines at the time to make it scale well enough.

So were people not actually writing code for PowerPC? No, lot's of people were. I'd actually guess that after Apple left PowerPC, the number of PowerPC developers continued to rise. And with the Xbox 360, Sony PS3, and the Nintendo Wii/Wii U continuing to get new games, there are still a lot of PowerPC developers out there.

Re:Fsck x86

[UnknowingFool]

They both shifted from a proprietary processor and chipset to a more common and popular platform. Both platforms had specific benefits over x86 until x86 scaled far and beyond what they both offered.

In my opinion, Apple shifted to x86 mainly for logistical reasons not architectural reasons. The problem with staying with PPC was two fold: 1) Intel offered better laptop chips and 2) Apple was going to have problems with PPC supplies.

The first one is fairly self-evident. Intel laptop chips were being updated all the time and they were better at power efficiency than the PPC4 based chips Apple was getting from Motorola. IBM never manufactured a mobile PPC5 chip probably because of the heat dissipation problems. If Apple stuck with IBM and PPC then they would have to be further behind Intel based mobile chips.

The second one is more complicated. Motorola then IBM supplied Apple with chips but even with millions of chips a year, Apple would be a small customer to either company. Compounding this is that Apple's chip was heavily customized so that it was costly to maintain and develop for any chip maker. Apple needed those customizations as other PPC chips by Motorola and IBM were not designed to be used for consumers in computers. For example IBM's chips for servers do not need any multimedia processing capabilities as they were designed for servers not desktops.

As such it was burden for Motorola and IBM to make changes to any supply schedules. If Apple got a sudden upswing in orders, IBM wouldn't be able to keep up. Also IBM would have to dedicate more and more resources to develop newer generations with Apple's changes and IBM was reluctant to spend possibly billions in research for one small customer.

Intel on the other hand was better logistically. Any development Intel did for Apple could be used for other customers. In fact, the ultrabook specifications came out of Intel's work with Apple on the MacBook Air.

"newsy" bits

[bill_mcgonigle]

Somehow missing from TFS...

Intel has released a beta of its native development environment called Intel Integrated Native Developer Experience, (INDE) and written plugins for Eclipse the most Android developers use to build for Android so the apps can be X86 compatible and execute efficiently on Atom processor-based hardware.

Apple did this when they switched to PPC.

[hey!]

It worked amazingly well, but it still sucked.

Re:Apple did this when they switched to PPC.

[Trepidity]

They had fat binaries for apps compiled to both PPC and x86, but that wasn't the only solution, since with just that you wouldn't be able to run apps until the developer recompiled and shipped a new version. They also had a binary translator to run unmodified PPC binaries on x86.

Re:Not very well written then

[Atzanteol]

A compiled binary doesn't care how well-written your C is if you are running it on the wrong platform.

Re:Not very well written then

[Mad Bad Rabbit]

Clearly we just need a small set of POSIX apps to do 'git, 'make' and 'gcc' on your phone.
Download the signed source code from the app store.

Bigger problem than Intel admits

[edxwelch]

ARM ran a survey of the top 500 Android apps in the market and found that only 20% are pure Java, 30% are native x86, 42% require binary translation and 6% do not work at all on Intel's platform. To make matters worse the level of compatibility is falling. They also found that running an app in binary translation mode takes a huge performance hit."
http://www.theregister.co.uk/2...

Re:Intel once made ARM processors...

[TheRaven64]

With ARMv8, a lot of companies have this kind of license. I think there are six independent ARMv8 implementations that I'm aware of, but there may be more. Well, I say independent - they all had engineers from ARM consult on the design, but they're quite different in pipeline structure. This is the problem Intel is going to face over the next few years. They could compete with AMD by outspending them on R&D: Intel could afford to design 10 processors and only bring 3 to market depending on what customers wanted, AMD couldn't afford to throw away that much investment. This is how the Pentium M happened: they rushed to market one of their back-burner designs. Now, however, they're competing with half a dozen companies all of whom have ISA-compatible chips and all of whom are content to heavily optimise their designs for a particular market segment.

Not useful to me, but I'll support Intel anyway.

[Dr. Manhattan]

I made an app for Android - ported an emulator written in C++. (Link in sig, if you're interested, but this isn't a slashvertisement.)

So the core of the app, the 'engine', is in C++ and must be natively compiled, while the UI and such is in Java. Naturally, the binary's compiled for ARM first. This actually runs on a lot of Intel Android tablets because they have ARM emulators. But, thanks to a user finally asking, I put in some time and now I can make an Intel version. (Heck, the original source was written for Intel anyway, so it wasn't a big stretch.) The existing tools are sufficient for my purposes. And it runs dramatically faster now on Intel.

However, for the developer it's mildly painful. The main issue is that you have a choice to make, with drawbacks no matter which way you go. You can include native libraries for multiple platforms, but that makes the APK larger - and according to a Google dev video I saw, users tend to uninstall larger apps first. In my case, it'd nearly double the size. So instead I'm putting together multiple APKs, so that ARM users get the ARM version and Intel users get the Intel version - but only Google Play supports that, not third-party app stores. I haven't looked into other app stores, and now it's less likely I will.

Note that native development can be important to apps for a non-technical reason: preventing piracy. An app written purely in Java is relatively easy to decompile and analyze, and pirates have a lot of techniques for removing or disabling licensing code. Adding a native component makes the app much harder to reverse-engineer, at least delaying the day that your app appears on pirate sites.

LLVM byte code

[reg]

I still don't understand why APKs are not just pure LLVM byte code, and either the store or the phone completes the byte code to native compile, including the final optimization passes...

Regards,
-Jeremy

Re:LLVM byte code

[outlaw]

Those who don't remember the past are doomed to repeat it...

http://en.wikipedia.org/wiki/A... (one of the earlier UNCOL)

I'll go back to my cave now

intel and power efficiency

[Mspangler]

"They've been actively focusing on increasing power efficiency for a number of years now, so I have no doubt they'll be able to bring strong competition."

It Intel wants to, they can bring strong competition. They used to have their own ARM variant, but sold it off. They decided that there was no future in low power. Oops.

When they do get a low power chip they seem to lose interest, and then crank up its performance, and its power budget. Then Steve Jobs would yell at them, and they would produce another low power chip. Then repeat the cycle. Now that Steve is gone, will they go back to thinking a 135W CPU is acceptable?

In Intel's world, Grand Coulee dam exists to power their CPU, and the rest of the hydropower on the Columbia is to run the cooling system for that chip. Institutionally they haven't figured out that we have all the cycles per second we need, and battery life is now the critical parameter. Obviously if your dream PC has a 1000 W power supply on a dedicated circuit you will not care about power the same way you will if your phone keeps going dead every time you need it.

As is often the case, the problem is Management, not Engineering.

For the record, I'm using a 2.5 Ghz Core 2 Duo P8700. It's 6 year old technology and entirely fast enough. It has a 25 W power budget. The "ultra-low power" 2 core Haswell has a 35 w power budget. So they have gone backwards. Remember, I don't need more speed, so I don't care if the Haswell CPU is faster.

The question is does Intel get this point? If they say "you are not our target demographic" then fine, and I'll pay them just as much attention as I pay to Miley Cyrus. Which is to say none.

Re:intel and power efficiency

[kevmatic]

You cannot use the TDP (the "power budget" in your post) to compare actual power consumption of the chips. The 35w Haswells will consume less power than your Core 2 chip in actual use, thanks to massive gating and idle power gains that Intel has made. Haswells are also faster, allowing them to go back to idle quicker.

That's the thing about Intel- some chips have higher TDPs, sure, but the performance per watt is unparalleled. You need more ARM cores to do the same things- and many people would like more performance, especially in the server and tablet markets. When the Cortex A15 was released, people were excited that the performance finally approached the Atom, but for some reason were surprised that power consumption started to come up as well... Huh, maybe Intel isn't terrible at the CPU thing after all?

Oh look- The Haswell dual core Core i5 4210Y has a TDP of 11.5W. And the quad core 4702EC is 27w...

They did not go backwards in any way shape or form.

By the way, Haswell's TDP includes the GPU. Penryn's GPU was on the northbridge and not included in CPU TDP. And the 945 GPU sucked compared to all the Haswells' GPUs.

Re:Intel is run by the filthy Juden.

[captjc]

Hey Juden, don't make it bad.
Take your sad chip and make it better.
Remember to put it into their phones
Then you can own
The Android market.

Re:Ha ha

[BasilBrush]

I'm lots older than that, and I don't remember any such complaints. Because originally the ARM chip was made only for the Acorn Archimedes. Which sold to people who certainly didn't want a PC clone. Later it started to be used as the CPU in PDAs, printers and mobile phones. None of which would have benefited at the time from Intel compatibility.

Issues with ARM not being x86 compatible are a recent thing.

Maybe there were complaints in the hobbyist Linux-everywhere crowd before there was an ARM port of Linux?

Re:Ha ha

[Wdomburg]

More to the point, the problem is that x86 is not compatible with ARM. And it's pretty much just a problem for Intel. So not really a problem at all.

Re:Ha ha

[Darinbob]

At this point, the tables are reversed, since what the actual Android users want is ARM compatibility, and x86 is the odd man out.
However, even in the ARM universe the compatibility is murky as there are so many varieties; straight up ARM, thumb, thumb-2, Jazelle as the basic instructions sets, plus some models that have multiply instructions, some have DSP instructions, and so on. Most of the Androids though presumably come with high end Cortex-A series and enough memory to use 32-bit ARM instructions which simplifies it.

They should have just done the whole thing in Forth, which can be faster than many VMs, low level enough to do everything you want, time tested and proven, and with optional nonportable escapes to assembler for special system operations.