[yocto] question about packagegroups

[Nicolas Dechesne]

hello,

i am creating a packagegroup to organize better my image/recipes. i am
doing something along these lines:

    DESCRIPTION = "My Custom Package Groups"

     inherit packagegroup

     PACKAGES = "\
         packagegroup-custom-apps \
         packagegroup-custom-tools \
         "

     RDEPENDS_packagegroup-custom-apps = "\
         dropbear \
         portmap \
         psplash"

     RDEPENDS_packagegroup-custom-tools = "\
         oprofile \
         oprofileui-server \
         lttng-control \
         lttng-viewer"

and in my imageA i am pulling *only* packagegroup-custom-tools with
IMAGE_INSTALL.

What I notice is that all packages listed in my packagegroup even the
ones from packagegroup-custom-apps which isn't pulled in my image are
built when building my image. Of course they are not installed, but
why are they built? it is wasting a large amount of time, while it's
not even needed. is that really expected or am i doing something wrong
here?

thanks

nicolas