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

[Stefan Eichenberger <eichest@gmail.com>]

Hi Joshua and Koen,

On Tue, Apr 15, 2025 at 08:56:26AM +0200, Koen Kooi wrote:
> 
> 
> > 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 :)

This is the exact same issue we have.

> > 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!

I also don't like the sed approach because exactly of what Koen says. I
agree that one of the base problem is that we already modify the policy
and not just use systemds default. If we just remove the "mac" part that
would be good for us as well.

Regards,
Stefan