Samsung Galaxy Alpha (samsung-sltexx)
A tiny, yet quite powerful Samsung phone. Presented in 2014, the Alpha features one of the earliest octa-core Exynos CPUs, matched with a 4.7" AMOLED display and 4G modem.
Users owning this device
How to enter flash mode
Turn off, then hold down volume down, home key, and press the power button at the same time. See this video
No port at the moment. Sadly, this 32-bit Exynos has zero mainline support at the moment. Since it was only used on Alpha, A7 and Meizu MX4 Pro, it is quite unlikely that a mainline port will see the light soon.