[Openembedded-architecture] Fwd: [meta-freescale] [meta-fsl-arm PATCH v3 04/17] machine-overrides-extender.bbclass: Automatically set extend the MACHINEOVERRIDES

[Trevor Woerner]

Hi,

Maybe this is a discussion for oe-architecture?

A while back Otavio introduced a class in meta-freescale
(machine-overrides-extender) that makes it easy for a BSP to specify
{two?|multiple?} sets of configurations for a given MACHINE. Why would
a BSP want to do that? Because in some cases there are multiple
choices for the user. For example: for the kernel, the user could
choose either the vendor kernel or the upstream kernel. However,
sometimes these decisions are "locked" together: i.e. if you want to
use the vendor's binary blob for (say) graphics, then you have to use
their vendor kernel as well. It's not possible for a user to choose,
say, the graphics binary blob but want to use the upstream kernel too.
Therefore the BSP ends up with "sets" of configurations which need to
be taken collectively instead of piecemeal.

In the example of meta-freescale, if the user does nothing special,
they get the vendor options. If they add the following line to their
configuration, they get the upstream pieces:

     MACHINEOVERRIDES .= ":use-mainline-bsp"

There is a definite need for this capability. I hope to move this
class from meta-freescale to openembedded-core so that all BSPs could
take advantage of it. Does that sound reasonable? Or maybe people
could suggest other mechanisms (existing or not) for handling this
situation?

The class can be found here:
https://github.com/Freescale/meta-freescale/blob/master/classes/machine-overrides-extender.bbclass

An example of its use can be found here:
https://github.com/Freescale/meta-freescale/blob/master/conf/machine/include/imx-base.inc

Best regards,
    Trevor


---------- Forwarded message ----------
From: Otavio Salvador <otavio.salvador at ossystems.com.br>
Date: Wed, Jul 12, 2017 at 2:11 PM
Subject: Re: [meta-freescale] [meta-fsl-arm PATCH v3 04/17]
machine-overrides-extender.bbclass: Automatically set extend the
MACHINEOVERRIDES
To: Trevor Woerner <twoerner at gmail.com>, Richard Purdie
<richard.purdie at linuxfoundation.org>
Cc: Otavio Salvador <otavio at ossystems.com.br>, meta-freescale Mailing
List <meta-freescale at yoctoproject.org>


On Wed, Jul 12, 2017 at 3:10 PM, Trevor Woerner <twoerner at gmail.com> wrote:
> Would it be feasible to have this in oe-core so other BSPs could use it?

I think so; it allows to reduce the amount of code duplication.

Richard, what do you think?

--
Otavio Salvador                             O.S. Systems
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