Re: [OE-core] [PATCH] systemd: Allow overriding PNI name policies

[Koen Kooi <koen.kooi@oss.qualcomm.com>]

> Op 14 apr 2025, om 19:03 heeft Joshua Watt via lists.openembedded.org <JPEWhacker=gmail.com@lists.openembedded.org> het volgende geschreven:
> 
> On Wed, Apr 9, 2025 at 4:15 AM Stefan Eichenberger via
> lists.openembedded.org <eichest=gmail.com@lists.openembedded.org>
> wrote:
>> 
>> From: Stefan Eichenberger <stefan.eichenberger@toradex.com>
>> 
>> Add two new variables, PNI_NAME_POLICY and PNI_ALTNAMES_POLICY, to allow
>> overriding the default Predictable Network Interface (PNI) name and
>> alternative name policies respectively.
>> 
>> This allows setting different name policies via a .bbappend file if the
>> defaults are not suitable for a specific use case.
> 
> It's very difficult to configured systemd in a way that is acceptable
> to everyone, and I'm not sure adding variable "knobs" for every
> possible configuration option is feasible for systemd.

For me, the issue is that OE-core adds the MAC naming feature that upstream has disabled by default, which gives me unpredictable names for various on-SoC network interfaces[1]. Having a way, supported by OE-core, to disable the addition that results in predictable names not being predictable would be great. It would make PNI function as intended :)

> You could do the exact same thing by putting your sed command in a
> do_install:append() function (since you want to set them from a
> bbappend anyway), and in that case it's irrelevant if pni-names is set
> in PACKAGECONFIG or not.

I know and I hate it:

https://github.com/qualcomm-linux/meta-qcom-distro/commit/1820fefb6c67506726277f7f789fd5a4538ea33f

It's fragile and noone on the oe-core side will realize that changing do_install() might break DISTROs that use such bbappend. A proper variable like Stefan proposes would be more obvious and less fragile.

Or we could just drop the bit that adds 'mac' and have DISTROs that want that write a bbappend!

regards,

Koen

[1] The interfaces lacking a MAC in hardware is a separate, but equally frustrating issue.

> 
>> 
>> Signed-off-by: Stefan Eichenberger <stefan.eichenberger@toradex.com>
>> ---
>> meta/recipes-core/systemd/systemd_257.4.bb | 12 ++++++------
>> 1 file changed, 6 insertions(+), 6 deletions(-)
>> 
>> diff --git a/meta/recipes-core/systemd/systemd_257.4.bb b/meta/recipes-core/systemd/systemd_257.4.bb
>> index 24aad11c0a..00edd702fb 100644
>> --- a/meta/recipes-core/systemd/systemd_257.4.bb
>> +++ b/meta/recipes-core/systemd/systemd_257.4.bb
>> @@ -273,6 +273,10 @@ WATCHDOG_TIMEOUT ??= "60"
>> # and the watchdog is enabled. (defaults is no hardware watchdog use)
>> WATCHDOG_RUNTIME_SEC ??= ""
>> 
>> +# Predictable network interface name policies
>> +PNI_NAME_POLICY ??= "keep kernel database onboard slot path mac"
>> +PNI_ALTERNATIVE_NAMES_POLICY ??= "database onboard slot path mac"
>> +
>> do_install() {
>>        meson_do_install
>> 
>> @@ -398,12 +402,8 @@ do_install() {
>>        fi
>> 
>>        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
>> +               sed -i 's/^NamePolicy=.*/NamePolicy=${PNI_NAME_POLICY}/' ${D}${nonarch_libdir}/systemd/network/99-default.link
>> +               sed -i 's/^AlternativeNamesPolicy=.*/AlternativeNamesPolicy=${PNI_ALTERNATIVE_NAMES_POLICY}/' ${D}${nonarch_libdir}/systemd/network/99-default.link
>>        else
>>                # Actively disable Predictable Network Interface Names
>>                sed -i 's/^NamePolicy=.*/NamePolicy=/;s/^AlternativeNamesPolicy=.*/AlternativeNamesPolicy=/' ${D}${nonarch_libdir}/systemd/network/99-default.link
>> --
>> 2.45.2
>> 
>> 
>> 
>> 
> 
> -=-=-=-=-=-=-=-=-=-=-=-
> Links: You receive all messages sent to this group.
> View/Reply Online (#214806): https://lists.openembedded.org/g/openembedded-core/message/214806
> Mute This Topic: https://lists.openembedded.org/mt/112169516/9418801
> Group Owner: openembedded-core+owner@lists.openembedded.org
> Unsubscribe: https://lists.openembedded.org/g/openembedded-core/unsub [koen.kooi@oss.qualcomm.com]
> -=-=-=-=-=-=-=-=-=-=-=-