How to filter a default NixOS module option value?

[SFrijters]

Recently I have started to take a look at the nonSource packages used on my system.
One of them is sof-firmware, which is added to my system via enableRedistributableFirmware.

I’m fine with the other firmware being added, but I don’t want to copy the list or re-implement the logic to generate the default - is there any proper way to do something like hardware.firmware = filter (some lambda) (the default / previous value) in my config? Overlays don’t work for this, right?

[tejing]

No, sorry. There just isn’t a way to do this. It’s one of the more annoying aspects of the module system. You have to replicate the value.

[SFrijters]

Thanks for the quick reply. That’s unfortunate but it’s good to know.

[waffle8946]

You can get the default value with options.<option path>.default, but this isn’t a default, this is just a module that sets some config.

Overlays operate on nixpkgs instances, not module system instances.

There is a previous discussion where @nrabulinski sent a PR to add the functionality you’re looking for, maybe you can give it a try.

Remove from list in NixOS Module (or HomeManager)

I did indeed, you’re probably referring to lib/modules: implement a way to override a property based on its previous value by nrabulinski · Pull Request #286578 · NixOS/nixpkgs · GitHub I remember there being some shortcomings with the implementation, but can’t recall what exactly. That, and the proposal itself was a bit controversial I’ll propose yet another cursed option though - extendModules and the approach GitHub - polygon/scalpel: Minimally invasive safe secret provis…

[SFrijters]

Interesting, but with a bunch of earlier attempts linked from that PR I don’t see something like that being introduced any time soon.

[waffle8946]

Of course not, it’s too controversial. I’m just sharing how it’s possible. I maintain an eternal nixpkgs fork anyway for my config, so I’d just pull it into my fork if I wanted to use it.