poky-distro-alt-test-config.inc: don't override PREFERRED_VERSION_linux-yocto

This overrides PREFERRED_VERSION_linux-yocto set in machine
config. Use ?= like in poky distro config so that machines
can override PREFERRED_VERSION_linux-yocto and for example
update to 6.16 kernel via machine config.

Signed-off-by: Mikko Rapeli <mikko.rapeli@linaro.org>
---
 meta-poky/conf/distro/include/poky-distro-alt-test-config.inc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Hi,

On Thu, Sep 04, 2025 at 12:59:43PM +0300, Mikko Rapeli wrote:
> This overrides PREFERRED_VERSION_linux-yocto set in machine
> config. Use ?= like in poky distro config so that machines
> can override PREFERRED_VERSION_linux-yocto and for example
> update to 6.16 kernel via machine config.

genericarm64 does not work well on devices which are not known
at compile time without udev and thus systemd.

This is why our genericarm64 test configurations use "poky-altcfg"
distro with systemd and not "poky" distro with sysvinit and no udev.

genericarm64 would also like to use the latest kernel, which right
now with 6.16 kernel includes a lot of fixes and enablers for more
HW support.

Could this change be considered?

Or are there any alternatives that we could use to for a combination
of latest stable kernel and systemd out of poky build configs?

Currently with "poky-altcfg" distro, we can't override the kernel version from
genericarm64 machine or local.conf build configurations. The distro
setting overrides these.

If this patch is applied, we can change the kernel version from
genericarm64 machine config or local.conf build config to get
a useful test combination.

Cheers,

-Mikko

> Signed-off-by: Mikko Rapeli <mikko.rapeli@linaro.org>
> ---
>  meta-poky/conf/distro/include/poky-distro-alt-test-config.inc | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/meta-poky/conf/distro/include/poky-distro-alt-test-config.inc b/meta-poky/conf/distro/include/poky-distro-alt-test-config.inc
> index da9199dcd4..5f86e36735 100644
> --- a/meta-poky/conf/distro/include/poky-distro-alt-test-config.inc
> +++ b/meta-poky/conf/distro/include/poky-distro-alt-test-config.inc
> @@ -2,7 +2,7 @@
>  DISTRO_FEATURES:append = " pam usrmerge"
>  
>  # Use our alternate kernel version
> -PREFERRED_VERSION_linux-yocto = "6.12%"
> +PREFERRED_VERSION_linux-yocto ?= "6.12%"
>  
>  # Ensure the kernel nfs server is enabled
>  KERNEL_FEATURES:append:pn-linux-yocto = " features/nfsd/nfsd-enable.scc"
> -- 
> 2.34.1
>

On Fri, 2025-09-26 at 10:51 +0300, Mikko Rapeli via lists.yoctoproject.org wrote:
> On Thu, Sep 04, 2025 at 12:59:43PM +0300, Mikko Rapeli wrote:
> > This overrides PREFERRED_VERSION_linux-yocto set in machine
> > config. Use ?= like in poky distro config so that machines
> > can override PREFERRED_VERSION_linux-yocto and for example
> > update to 6.16 kernel via machine config.
> 
> genericarm64 does not work well on devices which are not known
> at compile time without udev and thus systemd.

You're asking we add code to mandate systemd and disable sysvinit
builds for genericarm64?

We should also mandate the 6.16 kernel and drop support for 6.12?

By extension that means that musl isn't supported for genericarm64
without security issues for example.

That would be a major change to our current plans/policies :(.

So no, this simple change really isn't that simple.

Cheers,

Richard

Hi,

On Fri, Sep 26, 2025 at 05:05:44PM +0100, Richard Purdie wrote:
> On Fri, 2025-09-26 at 10:51 +0300, Mikko Rapeli via lists.yoctoproject.org wrote:
> > On Thu, Sep 04, 2025 at 12:59:43PM +0300, Mikko Rapeli wrote:
> > > This overrides PREFERRED_VERSION_linux-yocto set in machine
> > > config. Use ?= like in poky distro config so that machines
> > > can override PREFERRED_VERSION_linux-yocto and for example
> > > update to 6.16 kernel via machine config.
> > 
> > genericarm64 does not work well on devices which are not known
> > at compile time without udev and thus systemd.
> 
> You're asking we add code to mandate systemd and disable sysvinit
> builds for genericarm64?
>
> We should also mandate the 6.16 kernel and drop support for 6.12?

No, I'm not asking for these, but I'm asking for a build variant
with latest stable kernel and systemd for genericarm64. That does not
exist. We only have older 6.12 kernel and systemd in "poky-altcfg" distro
or newer 6.16 kernel and sysvinit from "poky" distro. And from machine
config side we can't change the kernel version for example to be 6.16
in poky master branch for genericarm64 because "poky-altcfg" overrides
that.

This issue is resolved when 6.12 kernel is removed from master branch
and 6.16 comes the default, but comes back when the next kernel stable
update comes along.

> By extension that means that musl isn't supported for genericarm64
> without security issues for example.
> 
> That would be a major change to our current plans/policies :(.
> 
> So no, this simple change really isn't that simple.

The selected kernel version is IMO an agreement between machine
and distro. Currently in "poky-altcfg" distro dictates and
machines can't influense that. I think machines should be able
to influence that and for example update the kernel on all genericarm64
builds to 6.16. Support for 6.12 continues in stable branch.

In current state, the pre-built genericarm64 binaries for "poky" and
"poky-altcfg" distros are not very useful from yocto/oe-core releases.
Thus we must rebuild and also apply patches to update the kernel,
patches because even local.conf build config can't change the kernel
version set in "poky-altcfg" distro.

Cheers,

-Mikko