[Xperia Z3 General] nailyk:
This is not a guide on how to install a recovery on your xperia device but a summary of the recovery you can use on it.

As there is a lot of different configuration (roms/kernel/bootloaders) causing trouble (bootloop or even bricking devices), it is easy to get lost in the amount of information I will try to make a resume.

#include <std/disclaimer.h>
/*
* I am not responsible for bricked devices, dead SD cards, thermonuclear
* war, or the current economic crisis caused by you following these
* directions. YOU are choosing to make these modifications, and
* if you point your finger at me for messing up your device, I will
* laugh at you.
*/

To get started a (perfectible) infographic to explain the (re)boot process of xperia Z devices. I try to include all the options (kernel with extract_elf_ramdisk, without, old/new bootloaders).

Obviously a phone only take path 1, 2 or 3 depending of the kernel version/implementation, that is why all kernel where not compatible with all recoveries.

Hope it's now easier to understand (re)boot process between kernels/recoveries.

As there is a lot of tricks to boot in recovery on our Z phones, kernels and recovery should be compatibles between us.

You must ensure compatibility between this pieces to avoid boot problems (kernel versions, selinux enforcing, etc...) but I try to make a recap:

╔═════════════════════╤═══════════════════╤═══════════════════════════════════╤════════════════════════╗
║ Kernel/Rom │ Locked bootloader │ old Bootloader │ new bootloader ║
╠═════════════════════╪═══════════════════╪═══════════════════════════════════╪════════════════════════╣
║ CyanogenMod 12.1 │ Not compatible │ FOTAKernel (3.4 + sepolicy <=26) │ FOTAKernel ║
╟─────────────────────┼───────────────────┼───────────────────────────────────┼────────────────────────╢
║ CyanogenMod 13.0 │ Not compatible │ FOTAKernel (3.10 + sepolicy <=30) │ FOTAKernel ║
╟─────────────────────┼───────────────────┼───────────────────────────────────┼────────────────────────╢
║ Omnirom │ Not compatible │ FOTAKernel (3.4 + sepolicy <=26) │ FOTAKernel ║
╟─────────────────────┼───────────────────┼───────────────────────────────────┼────────────────────────╢
║ stock based rom 5.1 │ XZdr │ XZdr │ 1.oldBL + 2.FOTAKernel ║
╟─────────────────────┼───────────────────┼───────────────────────────────────┼────────────────────────╢
║ stock based rom 6.0 │ XZdr / RecRoot v3 │ XZdr / RICDefeat │ 1.oldBL + 2.FOTAKernel ║
╟─────────────────────┼───────────────────┼───────────────────────────────────┼────────────────────────╢
║ Concept rom 5.1 │ ? │ ? │ 1.? + 2.FOTAKernel ║
╟─────────────────────┼───────────────────┼───────────────────────────────────┼────────────────────────╢
║ Concept rom 6.0 │ ? │ ? │ 1.? + 2.FOTAKernel ║
╚═════════════════════╧═══════════════════╧═══════════════════════════════════╧════════════════════════╝

This is the first version so some mistake can be in the table. Anyway read carefully the recoveries/roms instructions.

edit 2016/04/22: cannot find information on concept rom recoveries.

For reference, the boot process of other phones.

Source: http://www.slideshare.net/nanik/learning-aosp-android-booting-process

Source: https://tektab.com/2015/10/31/android-bootloaderfastboot-mode-and-recovery-mode-explained/

Source: http://plaintexttools.github.io/plain-text-table/

If you found something missing or perfectible, do not hesitate to informing me and I will make the correction asap.

Also as usal, feedbacks and contributions are welcome :)

Good luck!