Opting your app out from Windows Phone with 256 MB
This article explains how to set-up an app so that it cannot be installed on Windows Phone products with 256 MB of memory.
Apps that follow the guidance in the article Best practice tips for delivering apps to Windows Phone with 256 MB should run on Windows Phone products with 256 MB memory. However, there will be a few rare situations where you have specific needs that cannot be accomodated on 256 MB phones, such as when you have to reply on a PeriodicTask or a ResourceIntensiveTask to deliver an app's use case. In these cases you can opt-out from 256 MB phones.
Setting your app to opt-out from 256 MB phones
To opt-out your app from 256 MB phones you need to add the appropriate <Requirement /> XML element to your WmAppManifest XML file, as follows:
<!-- ... -->
<Requirement Name="ID_REQ_MEMORY_90" />
<!-- ... -->
This requirement won't impact the runtime behaviour of your app, but it will change how and to whom the Windows Phone Marketplace distributes your app.
Submitting your app to AppHub
After adding the requirement to your app's XAP you should see the following message on AppHub prior to submitting your app:
When a user with 256 MB phone attempts to download your app from the Windows Phone Marketplace they’ll encounter the following message:
Note that the app can't be installed as the Download and Buy buttons are not displayed.
Avoid opting-out apps from 256 MB devices
It's recommended to avoid opting your apps out of 256 MB devices. Apps that opt-out will lose out on a growing user base of 256 MB device owners. There are rare occasions that would excuse opting your apps out of 256 MB devices. For the overwhelming majority of apps following the advice found in the Best practice tips for delivering apps to Windows Phone with 256 MB article is more appropriate than disqualifying your apps from 256 MB devices.