[yocto] undocumented MACHINE_FEATURES, and what makes something a MACHINE feature?

[Robert P. J. Day]

... big snip ...

  finally have time to read paul's post on this so i'll go over this
again, but it seems that at the very least, what's needed is, in the
current reference manual, Chapter 10. Reference:Features:

http://www.yoctoproject.org/docs/latest/ref-manual/ref-manual.html#ref-features

there should be an explanation of COMBINED_FEATURES and how that
plays into possible configuration changes. there's absolutely no
mention of COMBINED_FEATURES anywhere in the reference manual except
in the variable glossary:

http://www.yoctoproject.org/docs/latest/ref-manual/ref-manual.html#var-COMBINED_FEATURES

and that explanation seems somewhat inadequate:

"A set of features common between MACHINE_FEATURES and
DISTRO_FEATURES. See the glossary descriptions for these variables for
more information."

  as i mentioned, that variable is defined *very* explicitly for a
*chosen* set of FEATURES in bitbake.conf:

COMBINED_FEATURES = "\
    ${@base_both_contain("DISTRO_FEATURES", "MACHINE_FEATURES", "alsa", d)} \
    ${@base_both_contain("DISTRO_FEATURES", "MACHINE_FEATURES", "bluetooth", d)} \
    ${@base_both_contain("DISTRO_FEATURES", "MACHINE_FEATURES", "ext2", d)} \
    ${@base_both_contain("DISTRO_FEATURES", "MACHINE_FEATURES", "vfat", d)} \
    ${@base_both_contain("DISTRO_FEATURES", "MACHINE_FEATURES", "irda", d)} \
    ${@base_both_contain("DISTRO_FEATURES", "MACHINE_FEATURES", "pcmcia", d)} \
    ${@base_both_contain("DISTRO_FEATURES", "MACHINE_FEATURES", "pci", d)} \
    ${@base_both_contain("DISTRO_FEATURES", "MACHINE_FEATURES", "usbgadget", d)} \
    ${@base_both_contain("DISTRO_FEATURES", "MACHINE_FEATURES", "usbhost", d)} \
    ${@base_both_contain("DISTRO_FEATURES", "MACHINE_FEATURES", "wifi", d)}"
COMBINED_FEATURES[vardeps] += "DISTRO_FEATURES MACHINE_FEATURES"

and i think that needs to be pointed out so people (like me :-) don't
get the wrong idea of what it represents.

  thoughts?

rday

-- 

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

Twitter:                                       http://twitter.com/rpjday
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