Microsoft Explains How Windows on Snapdragon Works

We also asked Microsoft if the new Qualcomm laptops meant Windows Phones were coming back, and, well, it didn't say no.

Could Windows Phone return? Maybe. At a Q&A with Microsoft and Qualcomm execs at Qualcomm's Snapdragon Summit, Qualcomm's Miguel Nunes said "different form factors" are coming for Windows 10 on Snapdragon, and Microsoft's Erin Chapple didn't count out the return of handhelds to Microsoft's lineup.

But for now, "we are talking about always-connected PCs," Chapple said in response to a question about Windows phones.

Nunes and Chapple were doing a deep dive into Windows on Snapdragon, trying to answer some of the hottest questions about running a previously X86-based operating system on the totally different ARM instruction set. That's been done before, actually: it was called Windows RT, and it failed. The big difference this time is that the OS runs "Win32" applications, arbitrary legacy Windows apps rather than just universal Apps from the Windows Store.

The OS itself has been re-coded for ARM, Chapple said. When it's passed a Win32 app, it converts chunks of the app's code into ARM code, which it caches in memory or on disk. So apps will run slower on their first launch, and faster once they've been used for longer or launched again, she said. The cache gets purged after a full reboot, but the laptops are meant to be put into standby rather than shut down, so the cache won't get purged that often.

Some system DLLs, meanwhile have been converted to ARM code while keeping X86 calling conventions, which is called a "compiled hybrid portable executable." That trick is used with Office, which remains X86 code so it can be compatible with Office plugins, Chapple said.

GPU-heavy or network-heavy software will run better than CPU-heavy software, because the kernel drivers are native ARM. Older software may run better than newer software, Chapple pointed out, in part because the system doesn't run 64-bit X86 apps and because the Snapdragon 835 is faster than older PC processors. The Snapdragon also doesn't thermally throttle in a laptop form factor, Nunes said, meaning that it can run at its maximum speed for longer in a thin-and-light laptop than a higher-power chip might.

In my experience with an Asus NovaGo laptop, the older X86 utility Audacity ran absolutely fine, while the newer Firefox Quantum browser took several app restarts to get working.

In addition to the NovaGo, Microsoft and Qualcomm also announced the HP Envy x2 and teased a third ARM-based laptop, and that was enough for the day. While Nunes was excited to suggest "different form factors and different price tiers" going forward, the execs didn't want to give a more detailed roadmap for Windows on Snapdragon in the future.

For now, Windows only runs on the Snapdragon 835, and you won't be able to install Windows on your own device, Chapple said, although Nunes said a white box version could be on a potential long-term roadmap.

"We'll expand these platforms in the future," Nunes said.

Source: Microsoft Explains How Windows on Snapdragon Works