Porting Guide

Marshmallow Porting Guide: 

Replace files from your Stock ROM to Port 

system/lib/
libMali.so
hwcomposer.mt6582.so
libaudio.primary.default.so
libcameracustom.so
libcamalgo.so
libcamdrv.so
libfeatureio.so

system/bin/
all gsm libs
rild 

system/etc/ 
bluetooth, firmware, wifi (replace entire folder)

In boot.img :
kernel
uvented.rc

Lollipop Porting Guide:

Replace files from your Stock ROM to Port 

system/lib/
libMali.so
hwcomposer.mt6582.so
libaudio.primary.default.so
libcameracustom.so
libcamalgo.so
libcamdrv.so
libfeatureio.so

system/etc/
 firmware

In boot.img :
kernel
uvented.rc

Guide to Port Sprout4 Roms :

Step 1 : Extract latest cm of your device.

Delete addon.h ,Apps,fonts,framework,media,priv-apps,build.prop
Step 2 : Paste the above mentioned folders from sprout to cm
Step 3 : Merge extra bins and libs from sprout
Step 4 : Paste extra permissions in cm (etc/permissions)
Step 5 : Copy linandroidserver.so , libandroidruntime.so , libandroidfw.so , libmedia_jni.so and replace in cm lib
Step 6 : Merge extra files in vendor folder from sprout
Step 7 : Merge app_process32 ,applypatch ,bootanimation ,dalvikvm32 ,drmserver ,mdnsd ,mediaserver ,serfaceflinger from sprout to cm (These are bins)
Step 8 : Take storage list ,vold ,sdcard ,boot.img which storage is non emulated

© Yazad Madam , Kishan P Patel & Suhail 

How to take logcat :

Getting to the point
1) Unpack boot.img , open default.prop
Change ro.secure to 0 , ro.adb.secure to 0 and ro.debuggable to 1..
2) Download adb fastboot essentials. Extract it .. Open the folder. Press shift key and right click.. Open command prompt
First use : adb devices
Type
Adb logcat > filename.txt
Check lines of E\, W\, F\
. ROM will boot soon smile emoticon3) When the phone is in bootloop:-
As soon as adb detects the device
This means that the logcat will be same in the file named filename. Disconnect phone after 10-12 seconds.. That much log is enough... Guys port ROMs ... Take logsIn the log ,Check the files related to the errors and fix them one by one