Why flag ?

• If the code changes has to be enabled only on certain scenarios or only applicable for specific boards , then we have to define the flag .

Defining a new flag 

• The flag has to be defined in ccsp_common.inc file
• There are two ways to define the flag

                      1. Having the flag enabled always
                      2. Enabling only for specific board or on specific condition

Having the flag enabled always 

• Go to ccsp_common.inc file
• Add the flag under "CFLAGS_append +="  

• Syntax

  CFLAGS_append +=  " <FLAG> "

  
  

• Sample 

  CFLAGS_append +=  "  .........  -DRDKB_FEATURE "Image Added
• By this method, the flag is always set to 1 always (true)
• Now add the flag at required pieces of code

Enabling only for specific board or on specific condition

...

• Add the flag using DISTRO_FEATURE in ccsp_common.inc file as below

• Syntax 

  CFLAGS_append += " ${@bb.utils.contains('DISTRO_FEATURES', '<keyword>', '<FLAG>', '', d)}"

  Sample

  CFLAGS_append += " ${@bb.utils.contains('DISTRO_FEATURES', 'rdkb', '-DRDKB_FEATURE', '', d)}"

  
  

• Now the flag has to be added in the platform specific .Now to enable the flag for the specific platform , invoke from platform specific machine conf file 

• Syntax

  DISTRO_FEATURES_append = " ........ <keyword> "

  
  

• Sample

  File : In Rpi, 

  
   In ccsp_common.inc

  Image Added

  
   In raspberrypi-rdk-broadband.conf
  

  DISTRO_FEATURES_append = " ........ rdkb "

• With this method, the flag is set to 1 for the specific platform
Now add the flag at required pieces of code

• Image Added

           This enables RDK_REF_PLATFORM_ flag for rpi platform . 

• Using DISTRO method 

1. the package enable/disable for the specific platform can be controlled 
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2. installation of file based on feature availability 
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3. Functionality of feature can be controlled
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