setting EXTRA_IMAGE_FEATURES explicitly in .bb file can screw things up

["Robert P. J. Day" <rpjday@crashcourse.ca>]

  a while back, i whined about the inconsistent usage of
EXTRA_IMAGE_FEATURES, like this as a snippet:

meta/recipes-sato/images/core-image-sato-sdk.bb:EXTRA_IMAGE_FEATURES += "tools-debug tools-profile tools-testapps debug-tweaks"
meta/recipes-rt/images/core-image-rt-sdk.bb:EXTRA_IMAGE_FEATURES += "tools-debug tools-profile tools-testapps debug-tweaks"
meta/recipes-extended/images/core-image-lsb-sdk.bb:EXTRA_IMAGE_FEATURES = "tools-debug tools-profile tools-testapps debug-tweaks"

notice the mixing of "+=" and "=", which seems messy.  then i ran
across this in core-image-lsb-sdk.bb:

IMAGE_FEATURES += "apps-console-core tools-sdk dev-pkgs ssh-server-openssh"
EXTRA_IMAGE_FEATURES = "tools-debug tools-profile tools-testapps debug-tweaks"

  that *can't* be right, can it?  the explicit setting of
EXTRA_IMAGE_FEATURES in that recipe file will override any such
setting in one's local.conf file, won't it?  and that's how the
current manual *advises* how to add more features through your
local.conf.

  i tested this target with a standard local.conf, and checked the
environment to see:

... snip ...
IMAGE_FEATURES="apps-console-core debug-tweaks tools-sdk
tools-testapps dev-pkgs tools-profile tools-debug ssh-server-openssh"

which looks fine according to the .bb file.

  but if i add the following to my local.conf file (as the manual
suggests i do to add another feature):

EXTRA_IMAGE_FEATURES = "nfs-server"

i see *no* difference in the environment.  hasn't the setting in the
.bb file overridden the one in my local.conf?

  i *can* get nfs-server added to my list of features with
(predictably):

IMAGE_FEATURES += "nfs-server"

but that doesn't strike me as a proper solution and will certainly
come as an unpleasant surprise to someone eventually.  thoughts?

rday

-- 

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Robert P. J. Day                                 Ottawa, Ontario, CANADA
                        http://crashcourse.ca

Twitter:                                       http://twitter.com/rpjday
LinkedIn:                               http://ca.linkedin.com/in/rpjday
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