Sony has recently been among the friendlier companies for custom ROM developers, but their devices still had a major hitch. They could not be booted from recovery, which meant third-party software had to modify the build system and if things went wrong, it was a lot more difficult to fix. To address this issue, Sony will begin releasing new bootloaders to allow booting from recovery.
This was first reported at FXP, home to developers who work exclusively with Sony devices to bring custom ROMs like CyanogenMod to end users. Official word should be coming soon, but the software is available to flash right now. If you plug in a compatible device and use Sony's official flash tool, you will see a bootloader upgrade available with the name "open devices."
Which devices are compatible? For now, just those with Cortex-A7 processors. Those are:
- Xperia T2 Ultra
- Xperia T3
- Xperia M2
- Xperia E3
More devices are expected soon, so don't panic if it doesn't yet apply to you. Remember that Sony hasn't even publicly discussed this, so they are probably hard at work to get a larger portion of their product line on board.
Once updated with the new bootloader, recoveries will work as they do on other devices. They will exist independently of the ROM and will be able to be used to install new operating systems and updates. This will be very big news to owners of Sony phones and tablets who like to flash custom software, as the process will soon become simplified and more developers will support Sony hardware.
Source: FXP Blog