Re: [OE-core] [PATCH 1/3] ovmf: simplify PACKAGECONFIG's default value

[Ross Burton <Ross.Burton@arm.com>]

On 11 May 2026, at 14:19, Quentin Schulz via lists.openembedded.org <quentin.schulz=cherry.de@lists.openembedded.org> wrote:
> 
>> -PACKAGECONFIG ??= ""
>> -PACKAGECONFIG += "${@bb.utils.filter('MACHINE_FEATURES', 'tpm', d)}"
>> -PACKAGECONFIG += "${@bb.utils.contains('MACHINE_FEATURES', 'tpm2', 'tpm', '', d)}"
>> +PACKAGECONFIG ?= "${@bb.utils.contains_any('MACHINE_FEATURES', 'tpm tpm2', 'tpm', '', d)}"
> 
> Just a heads up that this is *not* equivalent.
> 
> The use of ??= meant that any ?= (and ??=) parsed anywhere before that line is meant that it would set the default values, and then we would append to those default values tpm.
> 
> Now by merging those into a single ?=, a previous ?= will override this new ?= operator, meaning tpm won't make  it to the PACKAGECONFIG even if the MACHINE_FEATURES is set to tpm/tpm2. Also, an earlier ??= won't do anything anymore.
> 
> Whether that's an actual issue, I don't know, but you may break users.
> 
> Merging the two += into a single one would truly be equivalent.

The old value _was_ very un-idiomatic but the replacement is too.

However:

PACKAGECONFIG ??= "${@bb.utils.contains_any('MACHINE_FEATURES', 'tpm tpm2', 'tpm', '', d)}”

Is idiomatic and whilst a change of behaviour, it has the expected behaviour.  Can you use ??= and clarify that whilst this changes the behaviour in edge cases, what we prefer is consistency between recipes.

Ross