two identically-named machine .conf files in two different layers?

two identically-named machine .conf files in two different layers?

[Robert P. J. Day]

  just ran across someone else's OE work, where he pulled in a
standard layer that defined a machine, call it "machine.conf", then
added an internal layer with some tweaks but *also* contained a
machine definition file named precisely "machine.conf", which was just
the original file with some edits. so it wasn't extending or modifying
the original machine.conf, it was meant to completely override it.

  i was a bit confused as i'm not sure what even happens in a
situation like that. does one take precedence over the other based on
layer priority? or what?

rday

-- 

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

Twitter:                                       http://twitter.com/rpjday
LinkedIn:                               http://ca.linkedin.com/in/rpjday
========================================================================

Re: two identically-named machine .conf files in two different layers?

[Christopher Larson]

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On Fri, Jul 14, 2017 at 2:50 AM, Robert P. J. Day <rpjday@crashcourse.ca>
wrote:

>
>   just ran across someone else's OE work, where he pulled in a
> standard layer that defined a machine, call it "machine.conf", then
> added an internal layer with some tweaks but *also* contained a
> machine definition file named precisely "machine.conf", which was just
> the original file with some edits. so it wasn't extending or modifying
> the original machine.conf, it was meant to completely override it.
>
>   i was a bit confused as i'm not sure what even happens in a
> situation like that. does one take precedence over the other based on
> layer priority? or what?
>

Config files and classes are pulled in via relative paths, which are always
found via BBPATH, which in turn is defined based on layer.conf files. Since
any sane layer.conf file will append to BBPATH, BBPATH ends up obeying the
same order as BBLAYERS.

If you want layer A to override a config file or class in layer B, put
layer A before layer B in BBLAYERS in conf/bblayers.conf.
-- 
Christopher Larson
kergoth at gmail dot com
Founder - BitBake, OpenEmbedded, OpenZaurus
Senior Software Engineer, Mentor Graphics

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Re: two identically-named machine .conf files in two different layers?

[Peter Kjellerstedt]

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There is one exception to the rule that I am aware of: meta-poky (formerly known as meta-yocto) prepends itself to BBPATH rather than appending itself…

//Peter

From: openembedded-core-bounces@lists.openembedded.org [mailto:openembedded-core-bounces@lists.openembedded.org] On Behalf Of Christopher Larson
Sent: den 14 juli 2017 16:25
To: Robert P. J. Day <rpjday@crashcourse.ca>
Cc: OE Core mailing list <openembedded-core@lists.openembedded.org>
Subject: Re: [OE-core] two identically-named machine .conf files in two different layers?



On Fri, Jul 14, 2017 at 2:50 AM, Robert P. J. Day <rpjday@crashcourse.ca<mailto:rpjday@crashcourse.ca>> wrote:

  just ran across someone else's OE work, where he pulled in a
standard layer that defined a machine, call it "machine.conf", then
added an internal layer with some tweaks but *also* contained a
machine definition file named precisely "machine.conf", which was just
the original file with some edits. so it wasn't extending or modifying
the original machine.conf, it was meant to completely override it.

  i was a bit confused as i'm not sure what even happens in a
situation like that. does one take precedence over the other based on
layer priority? or what?

Config files and classes are pulled in via relative paths, which are always found via BBPATH, which in turn is defined based on layer.conf files. Since any sane layer.conf file will append to BBPATH, BBPATH ends up obeying the same order as BBLAYERS.

If you want layer A to override a config file or class in layer B, put layer A before layer B in BBLAYERS in conf/bblayers.conf.
--
Christopher Larson
kergoth at gmail dot com
Founder - BitBake, OpenEmbedded, OpenZaurus
Senior Software Engineer, Mentor Graphics

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