[yocto] how to understand the "PACKAGECONFIG_class-nativesdk " and "PACKAGECONFIG_class-target" ?

[Andre McCurdy]

On Tue, Aug 21, 2018 at 3:00 AM, tugouxp <13824125580 at 163.com> wrote:
> how to understand the two:
> "PACKAGECONFIG_class_target
> PACKAGECONFIG_class-nativesdk "
> semantics in bb files? i did not found any explanation on the official
> document,  so, please help me ,thanks !

They are conditional over-rides of the value of PACKAGECONFIG. The
first over-ride takes effect when building the recipe for the target
(ie the "normal" way to build a recipe, where the sources are cross
compiled to run on the target), invoked with "bitbake <recipename>".
The second over-ride takes effect when building the recipe for the SDK
(a special way to build a recipe so that the resulting binaries can
run on the host but are only linked with libraries which are shipped
with the SDK), invoked with "bitbake nativesdk-<recipename>".

Using these class specific over-rides to set PACKAGECONFIG differently
when building for the target, for native (ie over-ride _class-native)
or for the SDK allows the build to be configured differently in each
case. Often the native and SDK specific builds will enable fewer
features than the target builds.

Note that in your example the target specific over-ride is wrong - it
should be _class-target rather than _class_target.