This week Microsoft announced it would make good on its 2013 promise to let developers use any retail Xbox One as a dev kit, launching a preview version of the Dev Mode and laying out guidelines for how Xbox One system resources will be allocated for Universal Windows Platform game and app development.
Those guidelines are worth noting because they outline what system resources you can expect to gain access to if you're building a game without an official Xbox One dev kit from Microsoft, and therefore running it on the platform as a UWP app.
As we previously noted, in the current preview program only 448 MB of the Xbox One's 8 GB of RAM is made available to UWP apps and games running on the console, and that limit will grow to 1 GB in a future Dev Mode update. However, that limitation will be waived if you're running your app in the Visual Studio debugger.
Moreover, UWP apps and games are limited to accessing roughly half of the Xbox One's processing power -- 45 percent of its GPU and 2-4 cores of its 8-core CPU. DirectX12 is also not supported at this time -- only DirectX 11 Feature Level 10.
However, none of these limits apply if you're using an official Xbox One development kit, which you can only get from Microsoft by registering as a developer (through, say, the company's [email protected] self-publishing program.)
The fact that these limits also don't apply if you're debugging your game suggest that while Microsoft is happy to have people using retail Xbox Ones as test beds, it would prefer developers still use official dev kits to make games.