Question on the sequence conf file parsing. #yocto

Question on the sequence conf file parsing. #yocto

[Guo, Yanmei]

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Hi Yoctoers,

Trying to understand the sequence of conf file parsing when bitbake is running a build.
As a typical yocto project, we generally have local.conf, bblayers.conf, multiconfig/xxx.conf and distro.conf etc,
serving for different purposes. Is there a defined sequence in terms of which conf file is parsed first, which is last?
Especally, I am interested to know if `BBLAYERS` can be appended conditionally depending on a variable defined in a multiconfig file.

Thanks very much!

-May

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Re: [yocto] Question on the sequence conf file parsing. #yocto

[Khem Raj]

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Do

Bitbake -e busybox >& log

And look into log file it will show you the order

On Wed, Sep 25, 2024 at 8:09 PM Guo, Yanmei via lists.yoctoproject.org
<yanmei.guo=boeing.com@lists.yoctoproject.org> wrote:

> Hi Yoctoers,
>
> Trying to understand the sequence of conf file parsing when bitbake is
> running a build.
> As a typical yocto project, we generally have local.conf, bblayers.conf,
> multiconfig/xxx.conf and distro.conf etc,
> serving for different purposes. Is there a defined sequence in terms of
> which conf file is parsed first, which is last?
> Especally, I am interested to know if `BBLAYERS` can be appended
> conditionally depending on a variable defined in a multiconfig file.
>
> Thanks very much!
>
> -May
>
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Re: [yocto] Question on the sequence conf file parsing. #yocto

[Matthias Schoepfer]

Hi May,

maybe dynamic layers are a solution to your problem:

https://docs.yoctoproject.org/ref-manual/variables.html?highlight=bbfiles_dynamic#term-BBFILES_DYNAMIC

Regards,

    Matthias

On 9/26/24 05:09, Guo, Yanmei via lists.yoctoproject.org wrote:
> Hi Yoctoers,
> Trying to understand the sequence of conf file parsing when bitbake is 
> running a build.
> As a typical yocto project, we generally have local.conf, 
> bblayers.conf, multiconfig/xxx.conf and distro.conf etc,
> serving for different purposes. Is there a defined sequence in terms 
> of which conf file is parsed first, which is last?
> Especally, I am interested to know if `BBLAYERS` can be appended 
> conditionally depending on a variable defined in a multiconfig file.
> Thanks very much!
> -May
>
> -=-=-=-=-=-=-=-=-=-=-=-
> Links: You receive all messages sent to this group.
> View/Reply Online (#63887): https://lists.yoctoproject.org/g/yocto/message/63887
> Mute This Topic: https://lists.yoctoproject.org/mt/108661552/3618420
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Re: [yocto] Question on the sequence conf file parsing. #yocto

[Alexander Kanavin]

On Thu, 26 Sept 2024 at 05:09, Guo, Yanmei via lists.yoctoproject.org
<yanmei.guo=boeing.com@lists.yoctoproject.org> wrote:
> Trying to understand the sequence of conf file parsing when bitbake is running a build.
> As a typical yocto project, we generally have local.conf, bblayers.conf, multiconfig/xxx.conf and distro.conf etc,
> serving for different purposes. Is there a defined sequence in terms of which conf file is parsed first, which is last?
> Especally, I am interested to know if `BBLAYERS` can be appended conditionally depending on a variable defined in a multiconfig file.

It cannot. Perhaps it would help if you explain the use case. Why do
you need to include a layer (or not) depending on some variable? What
would happen if you simply always include it? Can you create two
separate build configurations, one with the layer, and another
without?

Generally it's a sign of badly written layer if merely including it
causes unwanted side effects, and that's the problem that should be
addressed.

Alex

Re: [yocto] Question on the sequence conf file parsing. #yocto

[Guo, Yanmei]

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We use multiconfig as our seperate build management so that we can reuse some build component but have different configurations.

It looks like BBLAYERS can't be appended in multconfig.conf?   So between multiconfigurations, they have to share the same BBLAYERS?

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Re: [yocto] Question on the sequence conf file parsing. #yocto

[ChenQi]

Merely adding layers to BBLAYERS changes nothing as long as those layers 
are yocto compliant. See yocto-check-layer-wrapper. In such case, 
sharing the same BBLAYERS should have no negative impact. If that's not 
the case, use yocto-check-layer-wrapper and fix the layer.

Regards,
Qi

On 9/27/24 10:59, Guo, Yanmei via lists.yoctoproject.org wrote:
> We use multiconfig as our seperate build management so that we can 
> reuse some build component but have different configurations.
> It looks like BBLAYERS can't be appended in multconfig.conf?  So 
> between multiconfigurations, they have to share the same BBLAYERS?
>
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Re: [yocto] Question on the sequence conf file parsing. #yocto

[Guo, Yanmei]

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Hi Alex,

Can you explain a bit more on separate build configurations?

We are using multi-config to separate the build configuration. However the `local.conf` and `bblayers.conf` are shared across.
unless you are suggesting complete new build (new local.conf and bblayers) not sharing anything in common.

In addition, is there a recommended way to manage debug/release build in which case they share common configurations but also varies in lots of areas.

Thanks,
Mei

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Re: [yocto] Question on the sequence conf file parsing. #yocto

[Guo, Yanmei]

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Adding layer can cause some unintended effects.
Taken recipes-kernel for example, if some layers being added eg meta-virtualization, bbappend will be applied to the kernel.
We might end up with some unexpected kernel feature being switched on.

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Re: [yocto] Question on the sequence conf file parsing. #yocto

[Alexander Kanavin]

On Thu, 10 Oct 2024 at 05:45, Guo, Yanmei via Lists.Yoctoproject.Org
<yanmei.guo=boeing.com@lists.yoctoproject.org> wrote:
> Can you explain a bit more on separate build configurations?
>
> We are using multi-config to separate the build configuration. However the `local.conf` and `bblayers.conf` are shared across.
> unless you are suggesting complete new build (new local.conf and bblayers) not sharing anything in common.

Yes, I'm suggesting exactly that. There are standard mechanisms
(configuration templates) that allow you to save and maintain these
files directly inside the layers, and initialize the build/ directory
using them.

> In addition, is there a recommended way to manage debug/release build in which case they share common configurations but also varies in lots of areas.

First, you should carefully consider if you need separate
debug/release builds at all. What would differ between them? Can you
achieve the same thing in a single build by having different image
recipes with their own set of packages and image tweaks? Can you
configure your software to make those decisions at runtime when it
starts (e.g. decide to run 'debug' or 'release' mode depending on what
is written into a target configuration file)?

If you do need two different builds (which will double the load on
your CI), then you should make two different distributions. They need
not be entirely separate: they can share almost everything in a common
.inc, and only a few tweaks in the top level distro.conf file. Then
local.conf only needs to set DISTRO to choose one or the other.

Alex