Windows 8 RT Running x86 Programs

Windows RT Running on ARM Has Full Win32 Compatibility.

As far back as I can remember the differences between the full version of Windows 8 and the tablet version, now dubbed Windows RT, were made pretty clear. Whilst the Modern UI section of them was going to be essentially identical the full version of Windows wasn’t going to run on anything that wasn’t x86 compatible and RT would be the version that could run on low power systems like ARM. This, logically, came with some draw backs the largest of which is the omission of the desktop environment on Windows RT devices. In all honesty this didn’t bother me as Microsoft is making a version of their Surface tablet (and I’m sure others will as well) that would run the full desktop anyway.

The delineation also made a lot of sense due to the different markets that both versions were targeting. The full version is squarely aimed at the desktop/laptop space whilst the RT version is strictly for mobile computing. In terms of functionality there’s a lot of crossover between these two spaces but the separation essentially meant that you had your desktop with its oodles of backwards compatibility that Microsoft is known for whilst also getting that nice, highly focused tablet environment should you want it.

However as it turns out Windows RT is far more full featured that I first thought and is capable of running Win32 applications:

Windows 8 RT Running x86 Programs

Thanks one intrepid user, Clrokr, over at XDA Developers it has been found out that Microsoft actually included full Win32 compatibility in Windows RT devices that run on the ARM architecture. Whilst this doesn’t mean you can straight up run those executables on said platform it does mean that any Windows application that you have the source of can be recompiled to run, without issue, on Windows RT devices. The above screenshot is from another user, peterdn, who has recompiled PuTTy to run on ARM and it appears to be functioning quite fine. Other applications have also been tested as well and shown to work as you’d expect.

Thinking about it more clearly this shouldn’t have come as a surprise as the architecture diagram for Windows 8 clearly shows that C/C++/C# are fully supported on both platforms and the inclusion of the desktop on Windows RT devices (again something I wasn’t aware of) would have you thinking everything was there to support this. As it turns out the only thing that was stopping this from working in the first place was runtime authentication level that was hard coded to only allow Microsoft signed applications to run in such an environment. The jailbreak that Clrokr details in this post is simply an in memory overwrite of this value which will allow any application to run. From there you just need to recompile your application and you’re golden.

The reasons for the lock out make sense from a business point of view: Microsoft was trying to create a pristine tablet environment that was tightly controlled in order to create a better experience. However at the same time porting all of the underlying architecture to ARM would have required quite a bit of effort and locking this functionality away from people seems like a strange idea. Whilst I’m not going to say they should unlock it for everyone having it as a configurable option would have meant that most users wouldn’t know about it but power users, like the ones who discovered this, could take advantage of it. I haven’t seen if Microsoft has made an official response to this yet or not but I’m sure they’d win more than a couple fans if they did this and it doesn’t look like it would be that hard to implement.

I was genuinely surprised by this as I hadn’t caught on pretty much all of Windows, including everything that makes it tick under the hood, had been ported across to the ARM architecture. I had believed that it was just a port of the core functionality required to support the WinRT framework but as the above screenshots prove Windows RT devices are pretty much fully fledged copies of Windows, they just need their applications recompiled in order to work. Of course questions of how those applications fair vs their modernized counterparts in a tablet environment remains to be seen but it’s interesting that the option is there and that Microsoft has gone to such lengths to keep people from fiddling with it.

 

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