ARM64EC: Building Native and Interoperable Apps for Windows 11 on ARM

This is not like Universal 2 on Apple&#x27;s transition, where you can have x64 and ARM versions of the program in the same binary (a &quot;fat&quot; binary). In Universal 2, the app runs as either 100% Intel or 100% ARM, depending on platform.<p>Instead, what ARM64EC is, is that you can put some ARM code inside a normally x64 binary and ship that to ARM customers like Surface Pro X users. ARM64EC doesn&#x27;t run on Intel. It&#x27;s just meant to speed up the porting effort of Intel programs to ARM because you don&#x27;t need to make everything ARM, just some of it, to go. The Intel bits will be translated using Microsoft&#x27;s slower-than-Rosetta-2-on-already-slow-hardware translator.<p>How many people will use this? Considering how successful Windows on ARM has been, coupled with how apathetic most Windows developers are... I give it a low chance, but who knows?

Are there finally fat binaries? Once again you would need to build and deploy separately for ARM. Put some logic into your installer or your software, which version to install.<p>macOS, iOS and Android have built in solutions for years, to just publish Packages with multiple architectures and the system executes the appropriate binary.

So is there any reason at all to use the original ARM64 ABI? Adding another ABI seems like a huge undertaking. Isn&#x27;t the original ARM64 windows ABI a fairly recent invention, too? Too bad they didn&#x27;t make it &quot;ARM64EC&quot; from the get-go?<p>Will there be two versions of every system dll, one for each ABI?

Microsoft is very likely going to make a second attempt at mobile hardware, but this time with a different strategic approach - one that allows everyone who bet on Windows 11&#x2F;ARM to be able to run whatever the like without the headaches so common for Android&#x2F;iOS.

I wonder if the next version of the raspberry pi would serve as a good system to run Windows on Arm on. If so, I could see opportunity for it to capture a large part of the low-end Windows market.

&gt; even a module can freely mix and match ARM64EC and x64 as needed<p>Looks great. It helps ARM migration for software that heavily depending native plugins maybe like DAW.

Is there any decent ARM CPU in works for this Windows on ARM that can be comparable to M1 in terms of performance?

Classic (Pre Mac OS X) Mac applications were 68k code blobs that lived in the resource fork of an application (The resource fork was basically a type&#x2F;id database where arbitrary data could be loaded into memory and purged (ore prevented from being purged) when memory was low.)<p>When the PowerPC transition took place, much of the system remained in emulated 68k. PowerPC applications were typically data fork (regular file) demand paged, but they could also live as resources. The point being, once you got some data in memory, you were able to call it 68k -&gt; PPC or PPC to 68k using something known as the MixedMode Manager.<p>Since a big part of the way the classic MacOS was designed was to supply function pointer callbacks, there was a tedious phase where you had to wrap any function pointers supplied to the system with a thunk that would perform the ABI translation for you.<p>You typically wouldn&#x27;t have to write those yourself - all the toolbox APIs had a macro &#x2F; inline defined that would create the thunk for you - the legacy of this can still be seen in the vestigial CarbonCore&#x2F;MixedMode.h and related headers.<p>Anyway, it was fairly trivial to wind up with code that not only mixed processor architectures and ABIs, but also supported in process loading of third party code (like PowerPC accelerated photoshop plugins, or After Dark screen saver modules.)

Microsoft one step closer to conquering the mobile space (who wouldn&#x27;t want an Android-compatible, ARM Windows phone that also serves as a desktop?)

Microsoft could make the uptake of their ARM64 hardware much more likely by offering all their software products on it for free for a few years until it gains some traction. I quite like my 1st gen SPX, but it&#x27;s certainly got some limitations. Windows 11 preview works pretty well on it so far, FWIW.

Super interesting! I wonder how close it is to the Rosetta 2 ABI mapping.

the idea of mix-and-matching architectures in one address space is the cool thing here.

Great to have some healthy competition, as long as they don&#x27;t force us to login using an Outlook account.

At this point I feel like supporting Windows in any way is probably immoral.

Because WinTel is so tied to closed source, backward binary compatibility, and binary distriboution, Microsoft is forever trapped in the x86 space.<p>For Microsoft to move to ARM, they will need to the whole Windows ecosystem, and every software maker to create, and maintain ARM versions of everything.<p>ARM64EC is a very desperate move to try working around that.<p>On Linux, it&#x27;s simple. .&#x2F;configure, make, and go for a coffee break.<p>Their decision to go with binary-centric model now came back to bite them. They have no future in the ARM dominated world.