[OE-core] argh ... "_append" versus "+=" and IMAGE_INSTALL confusion

[Robert P. J. Day]

On Thu, 29 Mar 2012, Paul Eggleton wrote:

> I think what the manual is attempting to mitigate is a situation
> where you do the following in your image recipe:
>
> -------- snip -------
> IMAGE_INSTALL += "somepackage1 somepackage2"
>
> inherit core-image
> -------- snip -------
>
> In this instance, because IMAGE_INSTALL is set via ?= within core-
> image.bbclass, IMAGE_INSTALL will only be set to "somepackage1
> somepackage2" since the value is already set by the time it gets to
> the ?=. This is clearly not what you would want by using +=.
>
> Doing the following in an image recipe will work properly however:
>
> -------- snip -------
> inherit core-image
>
> IMAGE_INSTALL += "somepackage1 somepackage2"
> -------- snip -------
>
> Personally I think the text you quoted from the manual should be
> adjusted; there's nothing wrong with IMAGE_INSTALL += _in an image
> recipe_ provided that you do it _after_ the inherit of core-image.

  that makes sense, but it seems that a lot of potential confusion
could be avoided if this construct was avoided entirely and replaced
by the appropriate use of CORE_IMAGE_EXTRA_INSTALL, no?

  from my position of naivete, i can see that messing with
IMAGE_INSTALL is dangerous if you don't truly know how it's being
manipulated in the underlyling class files.

  but the solution is right there in core-image.bbclass:

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

CORE_IMAGE_EXTRA_INSTALL ?= ""

IMAGE_INSTALL ?= "${CORE_IMAGE_BASE_INSTALL}"

  that is, stop messing with IMAGE_INSTALL and do your customization
with CORE_IMAGE_EXTRA_INSTALL.  isn't that what it was expressly
designed for?

rday

-- 

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

Twitter:                                       http://twitter.com/rpjday
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