From 12f553550f8fa63fb0e18d00ce769a4860ab4334 Mon Sep 17 00:00:00 2001
From: x7c2d <me@x7c2d.net>
Date: Sat, 25 Apr 2026 23:06:57 +0000
Subject: [PATCH] nixos/systemd-networkd: add new options for v260

systemd 260 introduces some new linkConfig options to configure ethernet
devices and a new [MobileNetwork] section (and options) to configure
cellular network connections using a new integration with ModemManager.

- https://github.com/systemd/systemd/releases/tag/v260
---
 nixos/lib/systemd-network-units.nix    |  4 ++
 nixos/modules/system/boot/networkd.nix | 58 ++++++++++++++++++++++++++
 2 files changed, 62 insertions(+)

diff --git a/nixos/lib/systemd-network-units.nix b/nixos/lib/systemd-network-units.nix
index 5d3e9b3c9351..ada010e2c58d 100644
--- a/nixos/lib/systemd-network-units.nix
+++ b/nixos/lib/systemd-network-units.nix
@@ -413,6 +413,10 @@ in
       [QuickFairQueueingClass]
       ${attrsToSection def.quickFairQueueingConfigClass}
     ''
+    + optionalString (def.mobileNetworkConfig != { }) ''
+      [MobileNetwork]
+      ${attrsToSection def.mobileNetworkConfig}
+    ''
     + flip concatMapStrings def.bridgeVLANs (x: ''
       [BridgeVLAN]
       ${attrsToSection x}
diff --git a/nixos/modules/system/boot/networkd.nix b/nixos/modules/system/boot/networkd.nix
index 0c74115c15a4..177478f28ac8 100644
--- a/nixos/modules/system/boot/networkd.nix
+++ b/nixos/modules/system/boot/networkd.nix
@@ -180,6 +180,12 @@ let
           "StatisticsBlockCoalesceSec"
           "MDI"
           "SR-IOVVirtualFunctions"
+          "ScatterGather"
+          "ScatterGatherFragmentList"
+          "TCPECNSegmentationOffload"
+          "TCPMangleIdSegmentationOffload"
+          "GenericReceiveOffloadList"
+          "GenericReceiveOffloadUDPForwarding"
         ])
         (assertValueOneOf "MACAddressPolicy" [
           "persistent"
@@ -271,6 +277,12 @@ let
           "auto"
         ])
         (assertRange "SR-IOVVirtualFunctions" 0 2147483647)
+        (assertValueOneOf "ScatterGather" boolValues)
+        (assertValueOneOf "ScatterGatherFragmentList" boolValues)
+        (assertValueOneOf "TCPECNSegmentationOffload" boolValues)
+        (assertValueOneOf "TCPMangleIdSegmentationOffload" boolValues)
+        (assertValueOneOf "GenericReceiveOffloadList" boolValues)
+        (assertValueOneOf "GenericReceiveOffloadUDPForwarding" boolValues)
       ];
 
       sectionSR-IOV = checkUnitConfig "SR-IOV" [
@@ -2413,6 +2425,38 @@ let
         (assertInt "PVID")
         (assertRange "PVID" 0 4094)
       ];
+
+      sectionMobileNetwork = checkUnitConfig "MobileNetwork" [
+        (assertOnlyFields [
+          "APN"
+          "AllowedAuthenticationMechanisms"
+          "User"
+          "Password"
+          "IPFamily"
+          "AllowRoaming"
+          "PIN"
+          "OperatorId"
+          "RouteMetric"
+          "UseGateway"
+        ])
+        (assertValuesSomeOfOr "AllowedAuthenticationMechanisms" [
+          "none"
+          "pap"
+          "chap"
+          "mschap"
+          "mschapv2"
+          "eap"
+        ] "")
+        (assertValueOneOf "IPFamily" [
+          "ipv4"
+          "ipv6"
+          "both"
+          "any"
+        ])
+        (assertValueOneOf "AllowRoaming" boolValues)
+        (assertRange "RouteMetric" 0 4294967295)
+        (assertValueOneOf "UseGateway" boolValues)
+      ];
     };
   };
 
@@ -3747,6 +3791,20 @@ let
       '';
     };
 
+    mobileNetworkConfig = mkOption {
+      default = { };
+      example = {
+        APN = "access-point-name";
+        AllowRoaming = false;
+      };
+      type = types.addCheck (types.attrsOf unitOption) check.network.sectionMobileNetwork;
+      description = ''
+        Each attribute in this set specifies an option in the
+        `[MobileNetwork]` section of the unit.  See
+        {manpage}`systemd.network(5)` for details.
+      '';
+    };
+
     name = mkOption {
       type = types.nullOr types.str;
       default = null;