use Linux kernel sources associated with openwrt by default

this is for the belkin rt3200, whose uboot doesn't do
extlinux but can load a fit from a ubifs. It adds the
a kernel+dtb as /boot/fit

THOUGHTS.txt

@@ -6634,3 +6634,39 @@ Read 7491584 bytes from volume recovery to 0000000048000000
    Using 'config-1' configuration
    Trying 'kernel-1' kernel subimage
      Description:  ARM64 OpenWrt Linux-6.6.45
+
+Sun Dec 22 17:39:56 GMT 2024
+
+From the output above it looks like the device I have plugged in has
+an openwrt "recovery" image but not a "production" image
+
+It also looks like it will be quite hard work to persuade it to boot
+from usb or anything. It doesn't have any of the extlinux stuff
+but it does have uefi for what that's worth
+
+default boot_production command reads a ubi volume called 'fit' and
+calls bootm on what it finds
+
+we could define boot_production to ubifsmount liminix; ubifs load
+<addr> <filename> (which is a fit) and bootm it. *presumably* we could
+do this from the openwrt recovery image
+
+but could we install the whole system using said recovery image?  I
+expect we could do, it only requires getting a tarball onto it and
+unpacking it
+
+however, extlinux is not going to be helpful
+(actually it might be a bit, if we ask it to write the fit as
+well as/instead of the individual files)
+
+maybe we need separate concepts of "the filesystem contains
+stuff we need for boot" and "the stuff we need is the stuff
+that extlinux needs"
+
+each bootloader makes an output called bootfiles, and
+the bootablerootdir output copies from bootfiles
+
+Mon Dec 23 18:28:50 GMT 2024
+
+it might be worth moving ubi option decls into the hardware module, if
+they're hardware-dependent

devices/belkin-rt3200/default.nix

@@ -76,11 +76,6 @@
       ];
       config = {
     kernel = {
-      src = pkgs.pkgsBuildBuild.fetchurl {
-        name = "linux.tar.gz";
-        url = "https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.15.137.tar.gz";
-        hash = "sha256-PkdzUKZ0IpBiWe/RS70J76JKnBFzRblWcKlaIFNxnHQ=";
-      };
       extraPatchPhase = ''
           ${pkgs.openwrt.applyPatches.mediatek}
       '';

devices/families/qemu.nix

@@ -5,11 +5,6 @@
   ];
   config = {
     kernel = {
-      src = pkgs.pkgsBuildBuild.fetchurl {
-        name = "linux.tar.gz";
-        url = "https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.15.137.tar.gz";
-        hash = "sha256-PkdzUKZ0IpBiWe/RS70J76JKnBFzRblWcKlaIFNxnHQ=";
-      };
       config = {
         MTD = "y";
         MTD_BLOCK = "y";

devices/gl-ar750/default.nix

@@ -161,12 +161,6 @@
         appendDTB = true;
       };
       kernel = {
-        src = pkgs.pkgsBuildBuild.fetchurl {
-          name = "linux.tar.gz";
-          url = "https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.15.137.tar.gz";
-          hash = "sha256-PkdzUKZ0IpBiWe/RS70J76JKnBFzRblWcKlaIFNxnHQ=";
-        };
-
         # Mainline linux 5.19 doesn't have device-tree support for
         # this device or even for the SoC, so we use the extensive
         # OpenWrt kernel patches

devices/gl-mt300a/default.nix

@@ -114,11 +114,6 @@
      };
 
       kernel = {
-        src = pkgs.fetchurl {
-          name = "linux.tar.gz";
-          url = "https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.15.137.tar.gz";
-          hash = "sha256-PkdzUKZ0IpBiWe/RS70J76JKnBFzRblWcKlaIFNxnHQ=";
-        };
         extraPatchPhase = ''
           ${openwrt.applyPatches.ramips}
           ${openwrt.applyPatches.rt2x00}

devices/gl-mt300n-v2/default.nix

@@ -125,11 +125,6 @@
       };
 
       kernel = {
-        src = pkgs.fetchurl {
-          name = "linux.tar.gz";
-          url = "https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.15.137.tar.gz";
-          hash = "sha256-PkdzUKZ0IpBiWe/RS70J76JKnBFzRblWcKlaIFNxnHQ=";
-        };
         extraPatchPhase = ''
           ${openwrt.applyPatches.ramips}
         '';

devices/tp-archer-ax23/default.nix

@@ -50,11 +50,6 @@
       ];
       config = {
         kernel = {
-          src = pkgs.pkgsBuildBuild.fetchurl {
-            name = "linux.tar.gz";
-            url = "https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.15.137.tar.gz";
-            hash = "sha256-PkdzUKZ0IpBiWe/RS70J76JKnBFzRblWcKlaIFNxnHQ=";
-          };
           extraPatchPhase = ''
             ${pkgs.openwrt.applyPatches.ramips}
           '';

devices/zyxel-nwa50ax/default.nix

@@ -250,14 +250,8 @@
       #  IMAGE/ramboot-factory.bin := append-kernel | pad-to $$(KERNEL_SIZE) | append-ubi
 
       kernel = {
-        src = pkgs.fetchurl {
-          name = "linux.tar.gz";
-          url = "https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.15.137.tar.gz";
-          hash = "sha256-PkdzUKZ0IpBiWe/RS70J76JKnBFzRblWcKlaIFNxnHQ=";
-        };
         extraPatchPhase = ''
           ${openwrt.applyPatches.ramips}
-
         '';
         config = {
 

examples/recovery.nix

@@ -22,7 +22,6 @@ in rec {
     ../modules/outputs/ubimage.nix
     ../modules/outputs/jffs2.nix
     ../modules/outputs/ext4fs.nix
-    ../modules/outputs/extlinux.nix
   ];
 
   kernel.config = {

modules/kernel/default.nix

@@ -6,7 +6,7 @@
 { lib, pkgs, config, ...}:
 let
   inherit (lib) mkOption types ;
-  inherit (pkgs) liminix;
+  inherit (pkgs) liminix openwrt;
 
   mergeConditionals = conf : conditions :
     # for each key in conditions, if it is present in conf
@@ -21,8 +21,8 @@ let
 in {
   options = {
     kernel = {
-      src = mkOption { type = types.path; } ;
-      version = mkOption { type = types.str; default = "5.15.137";} ;
+      src = mkOption { type = types.path; default = openwrt.kernelSrc; } ;
+      version = mkOption { type = types.str; default = openwrt.kernelVersion;} ;
       modular = mkOption {
         type = types.bool;
         default = true;

modules/outputs.nix

@@ -13,7 +13,8 @@ in
   imports = [
     ./outputs/squashfs.nix
     ./outputs/vmroot.nix
-    ./outputs/extlinux.nix
+    ./outputs/boot-extlinux.nix
+    ./outputs/boot-fit.nix
     ./outputs/uimage.nix
     ./outputs/updater
   ];

modules/outputs/boot-fit.nix

@@ -0,0 +1,27 @@
+{
+  config
+, pkgs
+, lib
+, ...
+}:
+let
+  inherit (lib) mkIf mkEnableOption mkOption types concatStringsSep;
+  inherit (pkgs.pseudofile) dir symlink;
+  cfg = config.boot.loader.fit;
+  o = config.system.outputs;
+  cmdline = concatStringsSep " " config.boot.commandLine;
+  wantsDtb = config.hardware.dts ? src && config.hardware.dts.src != null;
+in {
+  options.boot.loader.fit.enable = mkEnableOption "FIT in /boot";
+
+  config = mkIf cfg.enable {
+    system.outputs.bootfiles = pkgs.runCommand "boot-fit" {} ''
+      mkdir $out
+      cd $out
+      cp ${o.uimage} fit
+    '';
+    filesystem = dir {
+      boot = symlink config.system.outputs.bootfiles;
+    };
+  };
+}

pkgs/openwrt/default.nix

@@ -29,6 +29,17 @@ let
   '';
 in {
   inherit src;
+
+  # The kernel sources typically used with this version of openwrt
+  # You can find this in `include/kernel-5.15` or similar in the
+  # openwrt sources
+  kernelSrc = pkgsBuildBuild.fetchurl {
+    name = "linux.tar.gz";
+    url = "https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.15.137.tar.gz";
+    hash = "sha256-PkdzUKZ0IpBiWe/RS70J76JKnBFzRblWcKlaIFNxnHQ=";
+  };
+  kernelVersion = "5.15.137";
+
   applyPatches.ath79 = doPatch "ath79";
   applyPatches.ramips = doPatch "ramips";
   applyPatches.mediatek = doPatch "mediatek"; # aarch64