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

[Robert P. J. Day]

On Fri, 15 Nov 2013, Burton, Ross wrote:

> On 15 November 2013 10:49, Robert P. J. Day <rpjday at crashcourse.ca> wrote:
> >   as you can see, the only tests for 'wifi' involve either
> > DISTRO_FEATURES or COMBINED_FEATURES, *not* MACHINE_FEATURES
> > individually. under the circumstances, then, can 'wifi' be considered
> > a legitimate MACHINE feature if it's never being tested in that
> > context? (the same can be said for 'bluetooth', by the way.)
>
> COMBINED_FEATURES is a union of MACHINE_ and DISTRO_FEATURES, so it
> does make sense for them to be listed as MACHINE_FEATURES as
> otherwise they can't be combined...  No point building wifi in the
> distro if the machine doesn't support it, and the machine supporting
> wifi isn't a reason to enable it in the distro.

  oh, wait, i think i see what's happening here. COMBINED_FEATURES is
*not*, as you claim, a simple union of MACHINE_ and DISTRO_FEATURES,
it's much more specific:

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)}"

and *now* it makes sense -- that's the missing test of
MACHINE_FEATURES i was looking for. more in a bit while i tease
through more files ...

rday

-- 

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

Twitter:                                       http://twitter.com/rpjday
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