Re: [docs] BB explanation of BB_ENV_PASSTHROUGH is confusing

[Quentin Schulz <quentin.schulz@cherry.de>]

Hi Richard, Robert,

On 1/7/26 3:46 PM, Richard Purdie via lists.yoctoproject.org wrote:
> On Wed, 2026-01-07 at 06:39 -0800, Robert P. J. Day via lists.yoctoproject.org wrote:
>>
>> here:
>>
>> https://docs.yoctoproject.org/bitbake/bitbake-user-manual/bitbake-user-manual-ref-variables.html#term-BB_ENV_PASSTHROUGH
>>
>> the explanation:
>>
>> "Specifies the internal list of variables to allow through from the
>> external environment into BitBake’s datastore. If the value of this
>> variable is not specified (which is the default), the following list
>> is used: BBPATH, BB_PRESERVE_ENV, BB_ENV_PASSTHROUGH, and
>> BB_ENV_PASSTHROUGH_ADDITIONS."
>>
>> seems weird since it suggests that if the value of that variable is
>> not specified, the list that is used recursively *includes* the
>> variable itself. and this doesn't seem to match the code from
>> lib/bb/utils.py, which does *not* include that variable:
>>
>>    def preserved_envvars():
>>      """Returns the list of variables which are taken from the environment and
>>      placed in the metadata."""
>>      v = [
>>          'BBPATH',
>>          'BB_PRESERVE_ENV',
>>          'BB_ENV_PASSTHROUGH_ADDITIONS',
>>      ]
>>      return v + preserved_envvars_exported()
>>
>> can someone clarify how that explanation should be interpreted? or how
>> it might be made clearer?
> 
> It probably needs updating after this:
> 
> https://git.openembedded.org/bitbake/commit/lib/bb/utils.py?id=0a33b560233b983456178541603ab96fea22238b
> 

See 
https://lore.kernel.org/yocto-docs/20260114-env-passthru-v1-1-fd5ef76eab61@cherry.de/

Cheers,
Quentin