The Android OS is known for being very open and flexible to the point that dozens of third-party Android versions, called ROMs, have been developed. That said, Android is setup in such a way that one device can really only boot into one Android system at a time, making it difficult, though not impossible, to juggle different ROMs on a single device. That, however, might be thing of the past as there is a chance that the upcoming Google Pixel and Pixel XL smartphones can actually dual boot two Android systems with less risk than before.
The theory was put forward by Dees_Troy, the lead developer behind the highly popular TWRP custom recovery software. In his investigation into Android 7.0 Nougat’s internals, primarily in order to make TWRP compatible, he discovered that new Nougat smartphones would actually have duplicate copies of system partitions in a device inn order to facilitate Nougat’s new seamless software update feature.
As a bit of a technical background, partitions are portions of a storage, be it hard disk, SSD, or eMMC/UFS like on smartphones, that have been set aside for a specific purpose or data, so that they would appear as if they were another separate storage (think another “drive letter” in Windows). Android has a a few such partitions in a regular installation but under Nougat, new devices would have duplicate partitions for system-related (in other words, not user data) files.
The reason for this is that Nougat features a new seamless update that Android borrowed from its Chrome OS cousin. Before Nougat, a firmware update required users to sit out the update while the system installs new downloaded files, in order to make sure that apps don’t accidentally use a file that’s being updated. In Android 7.0, the update is actually applied on the duplicate system partitions. After that has been successfully installed, the system prompts the user to reboot, at which points the partitions are “swapped” so that the system boots into the freshly updated partition.
Dees_Troy speculates that this system can be utilized to allow users to boot between two different Android installations, like between a stock manufacturer firmware and, say, CyanogenMod. Currently such dual, even multi, boot arrangements is already possible via MultiROM. However, that is basically a hack that carries far more risk than advantages. While the new Nougat partitions would limit it to at least two Android ROMs, the facilities would, in theory, at least be supported by Android itself.
Of course, that’s the theory, based on Dees_Troy’s analysis. It still has to be proven in practice, which probably won’t be possible until the new Pixel smartphones comes out. That’s mostly because only new smartphones that ship with Nougat will actually be set up with multiple, duplicate partitions. If this all turns out to be true, the Pixel and Pixel XL could probably quickly rise up to become Android power users’ smartphone of choice.