[PATCH optional] linux: use 6.18 for generic images

[colbyt <colby@colbyt.com>]

Keep the generic rootfs, app VM, net VM, and installer on the linux_6_18
package set after updating nixpkgs.

This is an optional conservative variant for deployments that should stay
on the Linux 6.18 LTS line instead of following linux_latest to Linux
7.1.1. With the new nixpkgs pin, that keeps the LTS track while updating
from Linux 6.18.2 to Linux 6.18.36.

Tested with the full integration suite on Linux 6.18.36.

Signed-off-by: colbyt <colby@colbyt.com>
---
 host/rootfs/default.nix             | 4 ++--
 img/app/default.nix                 | 4 ++--
 release/installer/configuration.nix | 2 +-
 vm/sys/net/default.nix              | 4 ++--
 4 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/host/rootfs/default.nix b/host/rootfs/default.nix
index 6bfeefb..334f5de 100644
--- a/host/rootfs/default.nix
+++ b/host/rootfs/default.nix
@@ -4,7 +4,7 @@
 
 import ../../lib/call-package.nix (
 { callSpectrumPackage, config, spectrum-build-tools
-, src, pkgsMusl, inkscape, linuxPackagesFor, linux_latest, xorg
+, src, pkgsMusl, inkscape, linuxPackagesFor, linux_6_18, xorg
 }:
 pkgsMusl.callPackage (
 
@@ -51,7 +51,7 @@ let
     system.stateVersion = trivial.release;
   });
 
-  kernel = linux_latest;
+  kernel = linux_6_18;
 
   appvm = callSpectrumPackage ../../img/app { inherit (foot) terminfo; };
   netvm = callSpectrumPackage ../../vm/sys/net { inherit (foot) terminfo; };
diff --git a/img/app/default.nix b/img/app/default.nix
index 71e6fa0..72d618b 100644
--- a/img/app/default.nix
+++ b/img/app/default.nix
@@ -5,7 +5,7 @@ import ../../lib/call-package.nix (
 { spectrum-app-tools, spectrum-build-tools, src, terminfo
 , lib, appimageTools, buildFHSEnv, runCommand, stdenvNoCC, writeClosure
 , erofs-utils, jq, s6-rc, util-linux, xorg
-, cacert, linux_latest
+, cacert, linux_6_18
 }:
 
 let
@@ -21,7 +21,7 @@ let
     else
       stdenvNoCC.hostPlatform.linux-kernel.target;
 
-  kernel = (linux_latest.override {
+  kernel = (linux_6_18.override {
     structuredExtraConfig = with lib.kernel; {
       DRM_FBDEV_EMULATION = lib.mkForce no;
       EROFS_FS = yes;
diff --git a/release/installer/configuration.nix b/release/installer/configuration.nix
index 3f9ef24..415e5e9 100644
--- a/release/installer/configuration.nix
+++ b/release/installer/configuration.nix
@@ -14,7 +14,7 @@ in
   boot.kernelParams = [ "udev.log_priority=5" ];
   boot.initrd.verbose = false;
 
-  boot.kernelPackages = pkgs.linuxPackages_latest;
+  boot.kernelPackages = pkgs.linuxPackagesFor pkgs.linux_6_18;
 
   boot.plymouth.enable = true;
   boot.plymouth.logo = pkgs.callPackage (
diff --git a/vm/sys/net/default.nix b/vm/sys/net/default.nix
index a722b02..fc7885e 100644
--- a/vm/sys/net/default.nix
+++ b/vm/sys/net/default.nix
@@ -7,7 +7,7 @@ pkgsMusl.callPackage (
 
 { lib, stdenvNoCC, nixos, runCommand, writeClosure
 , erofs-utils, jq, s6-rc, util-linux, xorg
-, busybox, dbus, execline, iwd, kmod, linuxPackagesFor, linux_latest
+, busybox, dbus, execline, iwd, kmod, linuxPackagesFor, linux_6_18
 , mdevd, nftables, s6, s6-linux-init, spectrum-driver-tools, xdp-tools
 }:
 
@@ -27,7 +27,7 @@ let
     else
       stdenvNoCC.hostPlatform.linux-kernel.target;
 
-  kernel = (linux_latest.override {
+  kernel = (linux_6_18.override {
     structuredExtraConfig = with lib.kernel; {
       DRM_FBDEV_EMULATION = lib.mkForce no;
       EROFS_FS = yes;
-- 
2.54.0