[yocto] section 5.2.3, dev manual, would seem to need clarification

[Robert P. J. Day]

  still poring over the dev manual, and in section 5.2.3:

"You can also customize an image by creating a custom recipe that
defines additional software as part of the image. The following
example shows the form for the two lines you need:

     IMAGE_INSTALL = "packagegroup-core-x11-base package1 package2"

     inherit core-image"

but that's not what that code is doing -- defining "additional"
software. it is completely *overriding* the image content that would
be used, based on this snippet from core-image.bbclass:

  CORE_IMAGE_BASE_INSTALL = '\
    packagegroup-core-boot \
    packagegroup-base-extended \
    \
    ${CORE_IMAGE_EXTRA_INSTALL} \
    '

  CORE_IMAGE_EXTRA_INSTALL ?= ""

  IMAGE_INSTALL ?= "${CORE_IMAGE_BASE_INSTALL}"

  inherit image

as i'm sure everyone knows, explicitly setting IMAGE_INSTALL in a
recipe promptly overrides that selection of CORE_IMAGE_BASE_INSTALL,
which represents a recipe defining precisely the contents of the
image, not the "additional" software to be added to an image.

  to avoid confusion, i think it would be worth expanding the
discussion of the use of IMAGE_INSTALL and IMAGE_FEATURES in the
core-image*bb files, since new readers might not appreciate the
distinction between using "=" and using "+=" in some of those recipe
files.

  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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