[yocto] Task dependencies

[Gary Thomas]

On 2017-04-13 09:34, Gary Thomas wrote:
> I'm trying to understand why 'perl' is being built for my target
> even though I don't mention it in any of the package recipes used
> to build that target.  When I used 'taskexp', I found that 'perl:do_build'
> only has a single dependent task, namely 'my-image:do_build'
> note: no perl packages end up in my image.
>
> This is just one example where it seems bitbake is doing a lot of
> unnecessary (certainly un-asked-for) work.
>
> How can I unravel this mystery?
>
> Thanks for any pointers
>

I think I've figured this out - my image includes a couple of
packages (i2c-tools, ntp) that each have some component that
needs perl although I don't install those components.  So it
now makes sense that perl has to be built for my target even
though I'm not actually using it.

For example, in i2c-tools I see
   RDEPENDS_${PN}-misc = "${PN} perl"
and since I don't actually install i2c-tools-misc, perl isn't
needed.

That said, I had to discover this by manually looking through the
task-depends.dot file as I did not see how to come up with this
answer using -u taskdep alone.

-- 
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Gary Thomas                 |  Consulting for the
MLB Associates              |    Embedded world
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