[Blu Pure XL] xathras:
I suffer from clinical depression and am liable to disappear for a few days from time to time - sorry, but there's nothing I can do about it. It's good to know that someone else is willing to have a go at this. I've put together these notes which I hope will cut down the time needed to get up to speed.

Once you have downloaded the Omni sources the next step is to set up the local "device tree" and that the required files are in the right place. To do a "lunch" first do - . build/envsetup.sh. The space is important. If vendorsetup.sh was found the output of this command will show it (see attached screenshot). Next do - lunch. The lunch menu will appear. Select the the entry for your phone. Next "roomservice" wiil start to assemble everything required for the build. There will be errors. Open roomservice.py in a text editor to see what code was being called. I couldn't fix the last error so I commented the relevant lines out to enable me to try a build.

That's about as far as I have got. My next task is to create a recovery.fstab and twrp.fstab. All the config files mentioned below are in a state of flux and still need lots of tweaking. One thing that does appear to work is that the architecture flags in BoardConfig.mk are accepted by lunch (judging by the lunch output).

Please post any errors, I might be able to help.

Device tree

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This has two meanings, the local device tree (mine is attached) and the remote device tree (on GitHub).

My working directory is ~/android/omni

Create this directory structure or (similar):

~/android/omni/device/vendor/gionee/products

~/android/omni/device/vendor/gionee/mt6795

You will probably use:

Vendor = Blu

Product = Pure_XL

Device = mt6795 or Helio_X10

Some files you will get to know (and there are probably a few more)

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~/vendor/vendorsetup.sh -This is needed to add the phone to the lunch menu.

~/vendor/gionee/products/e8phone.mk -The phone make file. Remove the # before the call inherit product.

~/vendor/gionee/products/AndroidProducts.mk -Where to find the phone make file.

~/vendor/gionee/mt6795/Android.mk -Needed to find the prebuilt kernel.

~/vendor/gionee/mt6795/product_config.mk -Overrides the defaults in config/config.make for <board_name>.

~/vendor/gionee/mt6795/BoardConfig.mk -The main mk file containing the device specifications.

~/omni/.repo/manifests/default.xml -Main project paths and repository.

~/omni/.repo/local_manifests/local_manifest.xml -Secondary projects, etc.

~/omni/.repo/roomservice.xml -Paths for roomservice to use.

~omni/build/tools/roomservice.py -Look at this when you get lots of roomservice error.

~/.bash.rc -Don't forget to make sure your paths point to the above!

Resources

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Setting Up A Compile Environment

http://docs.omnirom.org/Setting_Up_A_Compile_Environment

Establishing a Build Environment

https://source.android.com/source/initializing.html

How to compile TWRP touch recovery

http://xdaforums.com/showthread.php?t=1943625

Compile TWRP for any Android

http://tipsstrips.blogspot.co.uk/2015/02/compile-twrp-for-any-android.html

Learn about the repo tool, manifests and local manifest

http://xdaforums.com/showthread.php?t=2329228

How to push a device tree to github [beginners]

http://xdaforums.com/galaxy-grand-duos/general/guide-how-to-push-device-tree-to-github-t2788076

How to build from source, tutorial and troubleshooting

http://xdaforums.com/galaxy-grand-duos/general/guide-how-to-push-device-tree-to-github-t2788076

Building Android for a new Mobile Device

http://www.netmite.com/android/mydroid/development/pdk/docs/build_new_device.html

Recovery.fstab and TWRP.fstab

http://xdaforums.com/showthread.php?t=2499514&page=2

TARGET_PREBUILT_RECOVERY_KERNEL

http://xdaforums.com/showthread.php?t=2201860&page=489

Example - Custom TWRP recovery for Xiaomi Note 2 (Helio X10 based)

https://drive.google.com/file/d/0B9O9_6wNQG3DbnZtT0p4d0FMQ2M/view

Example - TWRP 2.8.7.0 Recovery for T310

http://mobileviandroid.blogspot.co.uk/2015/07/recovery-twrp-2870-recovery-for-t310.html