Finally! Boot to recovery enabled in special bootloaders from Sony
01 May 2015 • Posted by AdFad666
Sony Mobile devices are beautiful. So were the Sony Ericsson devices before them. Yet from Sony Ericsson Xperia X10 (the first device released with Android) to Sony Xperia Z3, developers have had a problem. None of these devices are able to boot from a recovery partition, which is one of the fundamental tasks required for installing and booting custom ROMs.
Of course, we’ve had CyanogenMod and AOKP and OmniROM and others for years. We worked around this limitation by packing both the boot ramdisk and the recovery ramdisk together in a single boot image. However this requires modifications to the Android build system, which makes it more difficult to work on new projects. Or to, you know, actually recover from a bad installation.
Today we finally have a real solution.
As part of the Open Devices initiative (and after years of harassment from FXP), Sony Mobile is releasing a set of special bootloaders that enables booting from the recovery partition. This allows us to use the normal recovery images built on any AOSP based project, even those only vaguely related such as Firefox OS and Ubuntu Touch. We no longer need to modify the build system.
The new bootloaders also fix some issues found while porting these devices to a newer 3.10 based kernel.
We’ll write more about the 3.10 kernel later, but briefly: the bootloader prepares the device and puts it into a specific configuration for the kernel. Due to various changes and improvements, the 3.10 based kernel expects a slightly different configuration compared to what a 3.4 based kernel expects. The bootloaders have been updated to reflect those changes.
The first devices to receive these bootloaders are the Cortex-A7 devices; Xperia T2 Ultra, Xperia T3, Xperia M2, and Xperia E3. We expect an official announcement from Sony Mobile very soon, but the bootloaders are already live and can be installed right now.
How do I install these bootloaders?
The easiest way is through Sony Mobile’s flash-tool. Assuming flash-tool is installed and your device is already unlocked, simply power down the device, hold the VOL-DOWN key and plug in the USB cable. You will see the LED flash green, then Flash-tool will recognise the device and offer the “Open devices” bootloader.
If you prefer the unofficial Flashtool by Androxyde check the device specific pages in the next few days for a link to an FTF package.
Once the new bootloader is installed, you enter fastboot mode by powering down the device, holding the VOL-UP key, and then plugging in the USB cable. You’ll see the LED shine blue, then you can install any recovery with a command such as:
fastboot flash recovery recovery.img
Entry to recovery is also simple. While the device is powered down, simply hold VOL-DOWN and then press and hold the POWER button. Keep both buttons held until you see the SONY splash logo. You will boot directly into recovery.
Now you never have to worry about which recovery a ROM has, or even if it has a recovery. It will always be installed on your device.