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I think ARM performance is still way off from the i5/i7 x86_64 you get at the higher-end macs, and rosetta-style x86_64 emulation on arm is probably even further off. Lack of virtualbox/vmware support is also a bit of a showstopper, at least for cross-browser testing and web development.

My guess is that ARM based high-end macs are at least 3-5 years away from today.

At least with Adobe CC being a monthly subscription and all, there won't be an extra upgrade cost for the arch switch :)

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Given the large base of x86 applications they will want to support, Apple might ship computers with both x86 and ARM chips. If the ARM chip was running the OS, it could turn off the x86 chip when it wasn't needed to reduce power consumption, and Apple might hope that applications would migrate to the ARM chip over time, until it could finally remove x86 entirely.

However, I would be worried about the power consumption of the two chips, even with the ability to turn off the x86 one on demand. Maybe Apple would be able to reduce the power consumption when the computer was running only on the ARM chip enough that it would be worth it overall.

But then all software will have to be shipped as ARM and as x86 binaries. Sure, that is possible engineering-wise, but at least the binaries are going to double in size. And there may be slight issues when you migrate applications between the ARM and x86 world with respect to data layout etc.

They already did that on the PPC -> x86 switch, and again on the 32bit to 64bit switch. iOS does it as well for the different version of arm. For most applications the code is smaller than the rest of the resources, so it's not really that big an issue.

http://en.wikipedia.org/wiki/Universal_binary

Running two ISAs at the same time is way more complicated than simply shipping two versions of the binary within the same file.

OSX always did that, more or less. It seems like it's only in the last few months with Chrome switching to 64bit that it's been possible to stay 64bit clean. Same with iOS, even the 64bit arm devices have to keep 32bit armv6/7 versions of all the frameworks around to be able to launch older appstore apps.

Sometimes they slip up, and I think it was Skype that ran into problems where some releases of OSX shipped a faulty or missing 32bit driver for some particular iSight/FacetimeCam models.

(on the other hand, as you say, it might be more difficult to run a multi processor setup sharing RAM and buses across completely incompatible ISAs.)

Didn't Apple do something like that before?

You know, Universal binaries that contained both PowerPC and Intel within a single fat binary...

Double size binaries is nothing compared to the amount of storage you have today.

They did and still do, sometimes even 3 or more archs in the same binary;

On OSX: combinations of PPC, x86, x86_64 could be built

On iOS: default at the moment is a triple of armv7, armv7s, arm64, I believe. For a while used to be armv6+armv7.

Support for this dates all the way back to NEXTSTEP which ran on multiple architectures (68K, x86, and IIRC Sparc and/or PA-RISC) back in the 1990s.

If Apple tried that, Intel would stop giving them such sweet prices.

I don't think Apple gives two hoots about VM support. They only released Bootcamp because it cost them almost nothing, but I think they would drop it in a heartbeat if it let them lower power consumption in laptops.

With the switch to x86 and with hardware virtualization available via virtualbox/vmware fusion/parallels, combined with a much larger user base with many having switched over from pc, I think they may find the demand for backwards compability and virtualization is much greater now than during their ppc->intel switch (which happened at a time where, at least from my vantage points, macs were still considered a fringe/specialists/niche platform)

Given how long Adobe took to add 64 bit support, I think we will be waiting for ARM ports of CC applications for a long time.

Adobe took forever to add 64-bit support because Apple wasn't offering 64-bit versions of many Classic Mac OS APIs, for x86-64 or PPC64. Now that Adobe's using OS X-native APIs, they can benefit from the proven portability of those frameworks: OS X has run on PPC, x86, and ARM in both 32-bit and 64-bit versions of each, and NeXTSTEP also ran on 68k, SPARC, and PA-RISC.

(Assuming Adobe isn't using lots of x86 assembly in its low level image/video code)

You might run into issues even if you don't use any assembly at all. For example, unlike x86, ARM doesn't support unaligned memory access. Took me some time to figure out when I ported some OS X code to iOS.

FWIW, there are ARM instructions for virtualisation. Linux's KVM hypervisor supports them.

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