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I am playing around with yocto for a personal project. I have a layer called meta-nightcore which has several files writen in different languages: bash, Python, C, C++ and several recipes.

Is it possible to exclude the meta-nightcore when calling bitbake <image_name> when a user defined variable NIGHTCORE_ENABLED? This variable is set via shell command before calling source oe-init-build-env.

If you have different ideas, can you also share?

Thanks anh Best Regards, Duy Tran

Duy Trần Phạm
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1 Answers1

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Yes, you can pass your environment variable into the build environment and then use it to conditionally add the extra layer(s).

You'll need to modify your bblayers.conf to store a default value for NIGHTCORE_ENABLED and to add the extra layer(s) to BBLAYERS if it is set to 1:

NIGHTCORE_ENABLED ?= "0"  # overridden by env if specified in BB_ENV_EXTRAWHITE
NIGHTCORE_LAYERS ?= "/path/to/poky/meta-nightcore"

BBLAYERS ?= " \
  /path/to/poky/meta \
  /path/to/poky/meta-poky \
  /path/to/poky/meta-yocto-bsp \
  ${@bb.utils.contains('NIGHTCORE_ENABLED', '1', '${NIGHTCORE_LAYERS}', '', d)} \
"

Then, you need to tell Bitbake to allow your environment variable to be captured into the Bitbake datastore by adding it to BB_ENV_EXTRAWHITE:

export NIGHTCORE_ENABLED=1
export BB_ENV_EXTRAWHITE="${BB_ENV_EXTRAWHITE} NIGHTCORE_ENABLED"

You can then run bitbake <image_name>.

Because bblayers.conf is usually generated when source oe-init-build-env is run for the first time, you may wish to use TEMPLATECONF to create a bblayers.conf.sample file that already includes this extra logic.

There's some related answers here too:

Is it possible to pass in command line variables to a bitbake build?

justinsg
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