trim down the qemu kernel config

just retain the options we need to pass the tests

devices/qemu/default.nix

@@ -14,157 +14,56 @@
   };
 
   overlay = final: prev:
-    let inherit (final) fetchFromGitHub;
+    let inherit (final) stdenvNoCC fetchFromGitHub;
     in {
       sources = {
-        kernel =  fetchFromGitHub {
+        kernel =
+          let src = fetchFromGitHub {
                 name = "kernel-source";
                 owner = "torvalds";
                 repo = "linux";
                 rev = "3d7cb6b04c3f3115719235cc6866b10326de34cd";  # v5.19
                 hash = "sha256-OVsIRScAnrPleW1vbczRAj5L/SGGht2+GnvZJClMUu4=";
               };
+          in  stdenvNoCC.mkDerivation {
+            name = "spindled-kernel-tree";
+            inherit src;
+            phases = [
+              "unpackPhase"
+              "patchScripts" "installPhase"
+            ];
+
+            patchScripts = ''
+              patchShebangs scripts/
+            '';
+            installPhase = ''
+              mkdir -p $out
+              cp -a . $out
+            '';
+          };
       };
     };
 
   kernel = {
-    config = {
+    checkedConfig = {
-      SYSVIPC= "y";
-      NO_HZ= "y";
-      HIGH_RES_TIMERS= "y";
-      LOG_BUF_SHIFT = "15";
-      NAMESPACES= "y";
-      RELAY= "y";
-      EXPERT= "y";
-      PERF_EVENTS= "y";
-      COMPAT_BRK= "n";
-      SLAB= "y";
       MIPS_MALTA= "y";
       CPU_LITTLE_ENDIAN= "n";
       CPU_BIG_ENDIAN= "y";
       CPU_MIPS32_R2= "y";
-      PAGE_SIZE_16KB= "y";
-      NR_CPUS= "1";
-      HZ_100= "y";
-      PCI= "y";
-      VIRTUALIZATION= "y";
-      KVM_MIPS_DEBUG_COP0_COUNTERS= "y";
-      MODULES= "y";
-      MODULE_UNLOAD= "y";
-      MODVERSIONS= "y";
-      MODULE_SRCVERSION_ALL= "y";
-      NET= "y";
-      PACKET= "y";
-      UNIX= "y";
-      NET_KEY= "y";
-      NET_KEY_MIGRATE= "y";
-      INET= "y";
-      IP_MULTICAST= "y";
-      IP_ADVANCED_ROUTER= "y";
-      IP_MULTIPLE_TABLES= "y";
-      IP_ROUTE_MULTIPATH= "y";
-      IP_ROUTE_VERBOSE= "y";
-      IP_PNP= "y";
-      IP_PNP_DHCP= "y";
-      IP_PNP_BOOTP= "y";
-      IP_MROUTE= "y";
-      IP_PIMSM_V1= "y";
-      IP_PIMSM_V2= "y";
-      SYN_COOKIES= "y";
-      TCP_MD5SIG= "y";
-      IPV6_ROUTER_PREF= "y";
-      IPV6_ROUTE_INFO= "y";
-      IPV6_OPTIMISTIC_DAD= "y";
-      IPV6_MROUTE= "y";
-      IPV6_PIMSM_V2= "y";
-      NETWORK_SECMARK= "y";
-      NETFILTER= "y";
-      NF_CONNTRACK_SECMARK= "y";
-      NF_CONNTRACK_EVENTS= "y";
-      IP_VS_IPV6= "y";
-      IP_VS_PROTO_TCP= "y";
-      IP_VS_PROTO_UDP= "y";
-      IP_VS_PROTO_ESP= "y";
-      IP_VS_PROTO_AH= "y";
-      VLAN_8021Q_GVRP= "y";
-      IPDDP_ENCAP= "y";
-      NET_SCHED= "y";
-      NET_CLS_ACT= "y";
-      NET_ACT_POLICE= "y";
-      GACT_PROB= "y";
-      MTD= "y";
-      MTD_BLOCK= "y";
-      MTD_CFI= "y";
-      MTD_CFI_INTELEXT= "y";
-      MTD_CFI_AMDSTD= "y";
-      MTD_CFI_STAA= "y";
-      MTD_PHYSMAP_OF= "y";
-      BLK_DEV_RAM= "y";
-      BLK_DEV_SD= "y";
-      BLK_DEV_SR= "y";
-      SCSI_CONSTANTS= "y";
-      SCSI_LOGGING= "y";
-      SCSI_SCAN_ASYNC= "y";
-      AIC7XXX_RESET_DELAY_MS="15000";
-      AIC7XXX_DEBUG_ENABLE= "n";
-      ATA= "y";
-      ATA_PIIX= "y";
-      PATA_OLDPIIX= "y";
-      PATA_MPIIX= "y";
-      ATA_GENERIC= "y";
-      PATA_LEGACY= "y";
-      MD= "y";
-      NETDEVICES= "y";
-      PCNET32= "y";
-      IPW2100_MONITOR= "y";
-      HOSTAP_FIRMWARE= "y";
-      HOSTAP_FIRMWARE_NVRAM= "y";
-      INPUT_MOUSEDEV= "y";
-      SERIAL_8250= "y";
-      SERIAL_8250_CONSOLE= "y";
-      POWER_RESET= "y";
-      POWER_RESET_PIIX4_POWEROFF= "y";
-      POWER_RESET_SYSCON= "y";
-      HWMON= "n";
-      FB= "y";
-      FB_CIRRUS= "y";
-      VGA_CONSOLE= "n";
-      FRAMEBUFFER_CONSOLE= "y";
-      RTC_CLASS= "y";
-      RTC_DRV_CMOS= "y";
-      EXT2_FS= "y";
-      EXT3_FS= "y";
-      JFS_POSIX_ACL= "y";
-      JFS_SECURITY= "y";
-      QUOTA= "y";
-      QFMT_V2= "y";
-      JOLIET= "y";
-      ZISOFS= "y";
-      PROC_KCORE= "y";
-      TMPFS= "y";
-      CONFIGFS_FS= "y";
-      JFFS2_FS_XATTR= "y";
-      JFFS2_COMPRESSION_OPTIONS= "y";
-      JFFS2_RUBIN= "y";
-      # NFS_FS= "y";
-      # ROOT_NFS= "y";
-      # NFSD= "y";
-      # NFSD_V3= "y";
-      CRYPTO_HMAC= "y";
-      RCU_CPU_STALL_TIMEOUT = "60";
-      ENABLE_DEFAULT_TRACERS = "y";
 
-      CFG80211= "y";
-      MAC80211= "y";
-      MAC80211_MESH= "y";
-      RFKILL= "y";
-      WLAN = "y";
-      MAC80211_HWSIM = "y";
       SQUASHFS = "y";
       SQUASHFS_XZ = "y";
+
+      VIRTIO_MENU = "y";
+      PCI = "y";
       VIRTIO_PCI = "y";
+      BLOCK = "y";
       VIRTIO_BLK = "y";
+      NETDEVICES = "y";
       VIRTIO_NET = "y";
+
+      SERIAL_8250= "y";
+      SERIAL_8250_CONSOLE= "y";
     };
   };
   outputs.default = "directory";

modules/base.nix

@@ -56,10 +56,13 @@ in {
 
         MODULES = "y";
 
-        # not going far without Unix domain sockets
+        # basic networking protocols
+        NET = "y";
         UNIX = "y";
         INET = "y";
         IPV6 = "y";
+        PACKET = "y";           # for ppp, tcpdump ...
+        SYSVIPC= "y";
 
         # s6-linux-init mounts this on /dev
         DEVTMPFS = "y";

modules/wlan.nix

@@ -0,0 +1,20 @@
+{ lib, pkgs, config, ...}:
+let
+  inherit (lib) mkEnableOption mkOption types isDerivation hasAttr ;
+  inherit (pkgs.pseudofile) dir symlink;
+  inherit (pkgs) busybox;
+
+in {
+  config = {
+    kernel = rec {
+      config = {
+        CFG80211= "y";
+        MAC80211= "y";
+        MAC80211_MESH= "y";
+        RFKILL= "y";
+        WLAN = "y";
+      };
+      checkedConfig = config;
+    };
+  };
+}

tests/wlan/configuration.nix

@@ -13,6 +13,13 @@ in rec {
       ];
     };
 
+  imports = [ ../../modules/wlan.nix ];
+
+  kernel.checkedConfig = {
+    MAC80211_HWSIM = "y";
+  };
+
+
   services.wlan = interface { type = "hardware"; device = "wlan0"; };
 
   services.hostap = hostapd (services.wlan) {