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From: "'Florian Bezdeka' via isar-users" <isar-users@googlegroups.com>
To: "Hombourger,
	Cedric (FT FDS CES LX)" <cedric.hombourger@siemens.com>,
	"Larson, Chris (FT FDS CES LX MEL)" <chris.larson@siemens.com>,
	"isar-users@googlegroups.com" <isar-users@googlegroups.com>
Subject: Re: [PATCH 0/2] Add support for per-kernel recipe variants
Date: Tue, 08 Apr 2025 10:29:24 +0200	[thread overview]
Message-ID: <cff584239104a4e7d061c73ad50646c63ce8f6c8.camel@siemens.com> (raw)
In-Reply-To: <9d9b56bd32d249bb97e50a1447870a1a6438facf.camel@siemens.com>

On Tue, 2025-04-08 at 08:18 +0000, Hombourger, Cedric (FT FDS CES LX)
wrote:
> On Tue, 2025-04-08 at 10:09 +0200, Florian Bezdeka wrote:
> > On Mon, 2025-04-07 at 09:01 -0700, chris.larson via isar-users wrote:
> > > From: Christopher Larson <chris.larson@siemens.com>
> > > 
> > > Add support for per-kernel recipe variants. This aids in the
> > > ability for a
> > > MACHINE to support multiple kernels, by allowing us to generate
> > > per-kernel
> > > variants in recipes like external kernel modules.
> > > 
> > > A new variable KERNEL_NAMES will list the kernels for which
> > > variants will be
> > > generated. It defaults to KERNEL_NAME. While this variable lists
> > > all supported
> > > kernels for the current machine, a variant will not be generated
> > > for
> > > KERNEL_NAME, assuming that's the recipe's baseline. Each variant
> > > listed in
> > > KERNEL_NAMES will add kernel-<kernel_name> to the OVERRIDES
> > > variable, and
> > > per-kernel:<kernel_name> to the BBCLASSEXTEND variable. In
> > > addition,
> > > KERNEL_NAME will be set to the kernel name for the current variant.
> > 
> > I'm missing the documentation for the new `KERNEL_NAMES` variable.
> > 
> > In addition you explained how this works, but what is the use case
> > behind? I can build multiple kernels per machine now, but when is
> > this
> > needed?
> 
> If you are wanting a concrete use-case noted in the documentation, it
> can certainly be added: no harm.
> 
> Concretely there are machine-supporting layers offering multiple
> kernels. Examples: "normal" kernel, PREEMPT_RT kernel. Another use-case
> until we get a .deb for each .ko (like in Yocto you can get an ipk for
> each ko), you may need a footprint-optimized kernel for e.g. a recovery
> image.
> 
> I hope that explains. Do let us know if the use-cases should be listed
> in the documentation. It would not be an issue to add them

I think it's worth to document KERNEL_NAMES with a complete example.

As I understand KERNEL_NAMES for now it's for building. So you can
build / select different kernels for your machine. OK, but where is the
decision taken which kernel is installed into which image?

That's the missing part for me.

> 
> > 
> > > 
> > > In a recipe that already uses KERNEL_NAME and appends it to its PN,
> > > all you
> > > need to do to use this is to inherit per-kernel, and add any
> > > additional kernels
> > > you want to support to KERNEL_NAMES. The second patch in this
> > > series
> > > does so for external kernel modules by default, but this will have
> > > no effect
> > > on existing recipes unless KERNEL_NAMES is set to something other
> > > than
> > > KERNEL_NAME.
> > > 
> > > Christopher Larson (2):
> > >   per-kernel.bbclass: add class
> > >   linux-module: inherit per-kernel
> > > 
> > >  meta/classes/per-kernel.bbclass             | 35
> > > +++++++++++++++++++++
> > >  meta/recipes-kernel/linux-module/module.inc |  2 +-
> > >  2 files changed, 36 insertions(+), 1 deletion(-)
> > >  create mode 100644 meta/classes/per-kernel.bbclass
> > > 
> > > -- 
> > > 2.47.2
> > 

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  reply	other threads:[~2025-04-08  8:29 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-04-07 16:01 chris.larson via isar-users
2025-04-07 16:01 ` [PATCH 1/2] per-kernel.bbclass: add class chris.larson via isar-users
2025-04-07 16:01 ` [PATCH 2/2] linux-module: inherit per-kernel chris.larson via isar-users
2025-04-07 19:25   ` 'cedric.hombourger@siemens.com' via isar-users
2025-04-08  8:07   ` 'Florian Bezdeka' via isar-users
2025-04-08  8:13     ` 'cedric.hombourger@siemens.com' via isar-users
2025-04-08 17:12       ` 'Larson, Chris' via isar-users
2025-04-08  8:09 ` [PATCH 0/2] Add support for per-kernel recipe variants 'Florian Bezdeka' via isar-users
2025-04-08  8:18   ` 'cedric.hombourger@siemens.com' via isar-users
2025-04-08  8:29     ` 'Florian Bezdeka' via isar-users [this message]
2025-04-08  8:34       ` 'cedric.hombourger@siemens.com' via isar-users
2025-04-08 10:05     ` 'Jan Kiszka' via isar-users
2025-04-08 10:29       ` 'cedric.hombourger@siemens.com' via isar-users

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