Re: [docs] [PATCH] migration-guides/migration-5.3.rst: add note on systemd pni-names change

["Antonin Godard" <antonin.godard@bootlin.com>]

On Tue Sep 9, 2025 at 3:59 PM CEST, Quentin Schulz via lists.yoctoproject.org wrote:
> Hi Antonin,
>
> On 9/9/25 3:29 PM, Antonin Godard via lists.yoctoproject.org wrote:
>> Add a migration note on the pni-names default policy change after commit
>> <> in OE-Core.
>> 
>
> General question, the systemd manpage specifies the policy as mac and 
> not MAC, should we follow that as well?
>
>> Cc: Koen Kooi <koen.kooi@oss.qualcomm.com>
>> Cc: Ross Burton <Ross.Burton@arm.com>
>> Signed-off-by: Antonin Godard <antonin.godard@bootlin.com>
>> ---
>>   documentation/migration-guides/migration-5.3.rst | 25 ++++++++++++++++++++++++
>>   1 file changed, 25 insertions(+)
>> 
>> diff --git a/documentation/migration-guides/migration-5.3.rst b/documentation/migration-guides/migration-5.3.rst
>> index 2d2f8d91a..8aa7b537f 100644
>> --- a/documentation/migration-guides/migration-5.3.rst
>> +++ b/documentation/migration-guides/migration-5.3.rst
>> @@ -118,6 +118,31 @@ class. Instead, one should create a new recipe to build this FIT image, as
>>   described in the :ref:`Removed Classes <migration-guides/migration-5.3:Removed
>>   Classes>` section of the Migration notes for |yocto-ver| (|yocto-codename|).
>>   
>> +systemd Predictable Interface Names no longer MAC policy by default
>> +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> +
>> +The :oe_git:`systemd recipe </openembedded-core/tree/meta/recipes-core/systemd>`
>> +used to forcibly set the MAC policy by default when the ``pni-names``
>> +:term:`distro feature <DISTRO_FEATURES>` was enabled. See
>
> s/was/is/ ?
>
>> +https://www.freedesktop.org/software/systemd/man/latest/systemd.link.html#AlternativeNamesPolicy=.
>> +
>> +This is no longer the case. Instead, when the ``pni-names`` :term:`distro
>
> SHould we justify here why it is no longer the case?
>
>> +feature <DISTRO_FEATURES>` is enabled, the default policy from systemd is
>> +selected (from https://github.com/systemd/systemd/blob/main/network/99-default.link).
>> +
>> +To set the MAC policy to systemd, add the following to a systemd ``.bbappend``
>
> s/to systemd/in systemd/ ?
>
>> +file in your custom layer::
>> +
>> +   do_install:append() {
>> +          if ${@bb.utils.contains('PACKAGECONFIG', 'pni-names', 'true', 'false', d)}; then
>> +                  if ! grep -q '^NamePolicy=.*mac' ${D}${nonarch_libdir}/systemd/network/99-default.link; then
>> +                          sed -i '/^NamePolicy=/s/$/ mac/' ${D}${nonarch_libdir}/systemd/network/99-default.link
>> +                  fi
>> +                  if ! grep -q 'AlternativeNamesPolicy=.*mac' ${D}${nonarch_libdir}/systemd/network/99-default.link; then
>> +                          sed -i '/AlternativeNamesPolicy=/s/$/ mac/' ${D}${nonarch_libdir}/systemd/network/99-default.link
>> +                  fi
>
> My brain's sh parser says this is invalid because we're missing a 
> closing fi for the outermost if block.

Yes, my bad I must have removed it by mistake

> I'm also a bit worried about this code snippet as it'll just not be 
> tested or maintained once this gets merged.

This snippet belongs to a release note for 5.3 so it already matches the Yocto
version? I will include the version of systemd version here at the time of
writing to give some more context.


Antonin

-- 
Antonin Godard, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com