build kernel only once for multiple outputs

e.g. vmlinux + zImage

devices/turris-omnia/default.nix

@@ -11,7 +11,21 @@
   };
 
   module = {pkgs, config, lib, lim, ... }:
-    let openwrt = pkgs.openwrt;
+    let
+      openwrt = pkgs.openwrt;
+      inherit (lib) mkOption types;
+      inherit (pkgs.liminix.services) oneshot;
+      inherit (pkgs) liminix;
+      mtd_by_name_links = pkgs.liminix.services.oneshot rec  {
+        name = "mtd_by_name_links";
+        up = ''
+          mkdir -p /dev/mtd/by-name
+          cd /dev/mtd/by-name
+          for i in /sys/class/mtd/mtd*[0-9]; do
+            ln -s ../../$(basename $i) $(cat $i/name)
+          done
+        '';
+      };
     in {
       imports = [
         ../../modules/arch/arm.nix
@@ -20,175 +34,205 @@
         ../../modules/outputs/mbrimage.nix
         ../../modules/outputs/extlinux.nix
       ];
-    kernel = {
-      src = pkgs.pkgsBuildBuild.fetchurl {
-        name = "linux.tar.gz";
-        url = "https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.15.71.tar.gz";
-        hash = "sha256-yhO2cXIeIgUxkSZf/4aAsF11uxyh+UUZu6D1h92vCD8=";
-      };
-      extraPatchPhase = ''
-          ${pkgs.openwrt.applyPatches.mvebu}
-      '';
+
       config = {
-        PCI = "y";
-        OF = "y";
-        MEMORY = "y"; # for MVEBU_DEVBUS
-        DMADEVICES = "y"; # for MV_XOR
-        CPU_V7 = "y";
-        ARCH_MULTIPLATFORM = "y";
-        ARCH_MVEBU = "y";
-        ARCH_MULTI_V7= "y";
-        PCI_MVEBU = "y";
-        AHCI_MVEBU = "y";
-        MACH_ARMADA_38X = "y";
-        SMP = "y";
-	      # this is disabled for the moment because it relies on a GCC
-        # plugin that requires gmp.h to build, and I can't see right now
-        # how to confgure it to find gmp
-        STACKPROTECTOR_PER_TASK = "n";
-        NR_CPUS = "4";
-        VFP = "y";
-        NEON= "y";
+        services.mtd-name-links = mtd_by_name_links;
+        kernel = {
+          src = pkgs.pkgsBuildBuild.fetchurl {
+            name = "linux.tar.gz";
+            url = "https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.15.71.tar.gz";
+            hash = "sha256-yhO2cXIeIgUxkSZf/4aAsF11uxyh+UUZu6D1h92vCD8=";
+          };
+          extraPatchPhase = ''
+          ${pkgs.openwrt.applyPatches.mvebu}
+        '';
+          config = {
+            PCI = "y";
+            OF = "y";
+            MEMORY = "y"; # for MVEBU_DEVBUS
+            DMADEVICES = "y"; # for MV_XOR
+            CPU_V7 = "y";
+            ARCH_MULTIPLATFORM = "y";
+            ARCH_MVEBU = "y";
+            ARCH_MULTI_V7= "y";
+            PCI_MVEBU = "y";
+            AHCI_MVEBU = "y";
+            MACH_ARMADA_38X = "y";
+            SMP = "y";
+	          # this is disabled for the moment because it relies on a GCC
+            # plugin that requires gmp.h to build, and I can't see right now
+            # how to confgure it to find gmp
+            STACKPROTECTOR_PER_TASK = "n";
+            NR_CPUS = "4";
+            VFP = "y";
+            NEON= "y";
 
-        # WARNING: unmet direct dependencies detected for ARCH_WANT_LIBATA_LEDS
-        ATA = "y";
+            # WARNING: unmet direct dependencies detected for ARCH_WANT_LIBATA_LEDS
+            ATA = "y";
 
-        PSTORE = "y";
-        PSTORE_RAM = "y";
-        PSTORE_CONSOLE = "y";
-        PSTORE_DEFLATE_COMPRESS = "n";
+            PSTORE = "y";
+            PSTORE_RAM = "y";
+            PSTORE_CONSOLE = "y";
+            PSTORE_DEFLATE_COMPRESS = "n";
 
-        SERIAL_8250 = "y";
-        SERIAL_8250_CONSOLE = "y";
-        SERIAL_OF_PLATFORM="y";
-        SERIAL_MVEBU_UART = "y";
-        SERIAL_MVEBU_CONSOLE = "y";
+            BLOCK = "y";
+            MMC="y";
+            PWRSEQ_EMMC="y";        # ???
+            PWRSEQ_SIMPLE="y";      # ???
+            MMC_BLOCK="y";
 
-        SERIAL_8250_DMA= "y";
-        SERIAL_8250_DW= "y";
-        SERIAL_8250_EXTENDED= "y";
-        SERIAL_8250_MANY_PORTS= "y";
-        SERIAL_8250_SHARE_IRQ= "y";
-        OF_ADDRESS= "y";
-        OF_MDIO= "y";
+            MMC_SDHCI= "y";
+            MMC_SDHCI_PLTFM= "y";
+            MMC_SDHCI_PXAV3= "y";
+            MMC_MVSDIO= "y";
 
-        WATCHDOG = "y";        # watchdog is enabled by u-boot
-        ORION_WATCHDOG = "y";  # so is non-optional to keep feeding
+            SERIAL_8250 = "y";
+            SERIAL_8250_CONSOLE = "y";
+            SERIAL_OF_PLATFORM="y";
+            SERIAL_MVEBU_UART = "y";
+            SERIAL_MVEBU_CONSOLE = "y";
 
-        MVEBU_DEVBUS = "y"; # "Device Bus controller ...  flash devices such as NOR, NAND, SRAM, and FPGA"
-        MVMDIO = "y";
-        MVNETA = "y";
-        MVNETA_BM = "y";
-        MVNETA_BM_ENABLE = "y";
-        SRAM = "y"; # mmio-sram is "compatible" for bm_bppi reqd by BM
-        PHY_MVEBU_A38X_COMPHY = "y"; # for eth2
+            SERIAL_8250_DMA= "y";
+            SERIAL_8250_DW= "y";
+            SERIAL_8250_EXTENDED= "y";
+            SERIAL_8250_MANY_PORTS= "y";
+            SERIAL_8250_SHARE_IRQ= "y";
+            OF_ADDRESS= "y";
+            OF_MDIO= "y";
 
-        MVPP2 = "y";
-        MV_XOR = "y";
+            WATCHDOG = "y";        # watchdog is enabled by u-boot
+            ORION_WATCHDOG = "y";  # so is non-optional to keep feeding
 
-        NET_DSA = "y";
-        NET_DSA_MV88E6XXX = "y"; # depends on PTP_1588_CLOCK_OPTIONAL
-      };
-    };
-    rootfsType = "ext4";
-    boot = {
-      commandLine = [
-        "console=ttyS0,115200"
-        "pcie_aspm=off" # ath9k pci incompatible with PCIe ASPM
-      ];
-      imageFormat = "fit";
-    };
-    filesystem =
-      let
-        inherit (pkgs.pseudofile) dir symlink;
-        firmware = pkgs.stdenv.mkDerivation {
-          name = "wlan-firmware";
-          phases = ["installPhase"];
-          installPhase = ''
+            MVEBU_DEVBUS = "y"; # "Device Bus controller ...  flash devices such as NOR, NAND, SRAM, and FPGA"
+            MVMDIO = "y";
+            MVNETA = "y";
+            MVNETA_BM = "y";
+            MVNETA_BM_ENABLE = "y";
+            SRAM = "y"; # mmio-sram is "compatible" for bm_bppi reqd by BM
+            PHY_MVEBU_A38X_COMPHY = "y"; # for eth2
+
+            MVPP2 = "y";
+            MV_XOR = "y";
+
+            # there is NOR flash on this device, which is used for U-Boot
+            # and the rescue system (which we don't interfere with) but
+            # also for the U-Boot environment variables (which we might
+            # need to meddle with)
+            MTD_SPI_NOR = "y";
+            SPI = "y";
+            SPI_MASTER = "y";
+            SPI_ORION = "y";
+
+            NET_DSA = "y";
+            NET_DSA_MV88E6XXX = "y"; # depends on PTP_1588_CLOCK_OPTIONAL
+          };
+        };
+        rootfsType = "ext4";
+        boot = {
+          commandLine = [
+            "console=ttyS0,115200"
+            "pcie_aspm=off" # ath9k pci incompatible with PCIe ASPM
+          ];
+          imageFormat = "fit";
+        };
+        filesystem =
+          let
+            inherit (pkgs.pseudofile) dir symlink;
+            firmware = pkgs.stdenv.mkDerivation {
+              name = "wlan-firmware";
+              phases = ["installPhase"];
+              installPhase = ''
             mkdir $out
             cp -r ${pkgs.linux-firmware}/lib/firmware/ath10k/QCA988X $out
           '';
-        };
-        in dir {
-          lib = dir {
-            firmware = dir {
-              ath10k = symlink firmware;
+            };
+          in dir {
+            lib = dir {
+              firmware = dir {
+                ath10k = symlink firmware;
+              };
+            };
+            etc = dir {
+              "fw_env.config" =
+                let f = pkgs.writeText "fw_env.config" ''
+                  /dev/mtd/by-name/u-boot-env 0x0 0x10000 0x10000
+                '';
+                in symlink f;
             };
           };
+
+        boot.tftp = {
+          loadAddress = lim.parseInt "0x1000000";
+          kernelFormat = "zimage";
+          compressRoot = true;
         };
 
-    boot.tftp = {
-      loadAddress = lim.parseInt "0x1000000";
-      kernelFormat = "zimage";
-      compressRoot = true;
+        hardware = let
+          mac80211 = pkgs.mac80211.override {
+            drivers = ["ath9k_pci" "ath10k_pci"];
+            klibBuild = config.system.outputs.kernel.modulesupport;
+          };
+        in {
+          defaultOutput = "mtdimage";
+          loadAddress = lim.parseInt "0x00800000"; # "0x00008000";
+          entryPoint = lim.parseInt "0x00800000"; # "0x00008000";
+          rootDevice = "/dev/mtdblock0";
+
+          dts = {
+            src = "${config.system.outputs.kernel.modulesupport}/arch/arm/boot/dts/armada-385-turris-omnia.dts";
+            includes =  [
+              "${config.system.outputs.kernel.modulesupport}/arch/arm/boot/dts/"
+            ];
+          };
+          flash.eraseBlockSize = 65536; # only used for tftpboot
+          networkInterfaces =
+            let
+              inherit (config.system.service.network) link;
+              inherit (config.system.service) bridge;
+            in rec {
+              en70000 = link.build {
+                # in armada-38x.dtsi this is eth0.
+                # It's connected to port 5 of the 88E6176 switch
+                devpath = "/devices/platform/soc/soc:internal-regs/f1070000.ethernet";
+                # name is unambiguous but not very semantic
+                ifname = "en70000";
+              };
+              en30000 = link.build {
+                # in armada-38x.dtsi this is eth1
+                # It's connected to port 6 of the 88E6176 switch
+                devpath = "/devices/platform/soc/soc:internal-regs/f1030000.ethernet";
+                # name is unambiguous but not very semantic
+                ifname = "en30000";
+              };
+              # the default (from the dts? I'm guessing) behavour for
+              # lan ports on the switch is to attach them to
+              # en30000. It should be possible to do something better,
+              # per
+              # https://www.kernel.org/doc/html/latest/networking/dsa/configuration.html#affinity-of-user-ports-to-cpu-ports
+              # but apparently OpenWrt doesn't either so maybe it's more
+              # complicated than it looks
+
+              wan = link.build {
+                # in armada-38x.dtsi this is eth2. It may be connected to
+                # an ethernet phy or to the SFP cage, depending on a gpio
+                devpath = "/devices/platform/soc/soc:internal-regs/f1034000.ethernet";
+                ifname = "wan";
+              };
+
+              lan = link.build {
+                ifname = "lan1";
+              };
+
+              wlan = link.build {
+                ifname = "wlan0";
+                dependencies = [ mac80211 ];
+              };
+              wlan5 = link.build {
+                ifname = "wlan1";
+                dependencies = [ mac80211 ];
+              };
+            };
+        };
+      };
     };
-
-    hardware = let
-      mac80211 = pkgs.mac80211.override {
-        drivers = ["ath9k_pci" "ath10k_pci"];
-        klibBuild = config.system.outputs.kernel.modulesupport;
-      };
-      in {
-        defaultOutput = "mtdimage";
-        loadAddress = lim.parseInt "0x00800000"; # "0x00008000";
-
-        entryPoint = lim.parseInt "0x00800000"; # "0x00008000";
-        rootDevice = "/dev/mtdblock0";
-        dts = {
-          src = "${config.system.outputs.kernel.modulesupport}/arch/arm/boot/dts/armada-385-turris-omnia.dts";
-          includes =  [
-            "${config.system.outputs.kernel.modulesupport}/arch/arm/boot/dts/"
-          ];
-        };
-        flash.eraseBlockSize = 65536; # only used for tftpboot
-        networkInterfaces =
-          let
-            inherit (config.system.service.network) link;
-            inherit (config.system.service) bridge;
-          in rec {
-            en70000 = link.build {
-              # in armada-38x.dtsi this is eth0.
-              # It's connected to port 5 of the 88E6176 switch
-              devpath = "/devices/platform/soc/soc:internal-regs/f1070000.ethernet";
-              # name is unambiguous but not very semantic
-              ifname = "en70000";
-            };
-            en30000 = link.build {
-              # in armada-38x.dtsi this is eth1
-              # It's connected to port 6 of the 88E6176 switch
-              devpath = "/devices/platform/soc/soc:internal-regs/f1030000.ethernet";
-              # name is unambiguous but not very semantic
-              ifname = "en30000";
-            };
-            # the default (from the dts? I'm guessing) behavour for
-            # lan ports on the switch is to attach them to
-            # en30000. It should be possible to do something better,
-            # per
-            # https://www.kernel.org/doc/html/latest/networking/dsa/configuration.html#affinity-of-user-ports-to-cpu-ports
-            # but apparently OpenWrt doesn't either so maybe it's more
-            # complicated than it looks
-
-            wan = link.build {
-              # in armada-38x.dtsi this is eth2. It may be connected to
-              # an ethernet phy or to the SFP cage, depending on a gpio
-              devpath = "/devices/platform/soc/soc:internal-regs/f1034000.ethernet";
-              ifname = "wan";
-            };
-
-            lan = link.build {
-              ifname = "lan1";
-            };
-
-            wlan = link.build {
-              ifname = "wlan0";
-              dependencies = [ mac80211 ];
-            };
-            wlan5 = link.build {
-              ifname = "wlan1";
-              dependencies = [ mac80211 ];
-            };
-          };
-      };
-
-  };
 }

modules/arch/arm.nix

@@ -4,6 +4,7 @@
     kernel.config = {
       OF = "y";
     };
+    kernel.makeTargets = ["arch/arm/boot/zImage"];
     hardware.ram.startAddress = lim.parseInt "0x40000000";
     system.outputs.u-boot = pkgs.ubootQemuArm;
   };

modules/kernel.nix

@@ -9,6 +9,7 @@ let
   inherit (pkgs.pseudofile) dir symlink;
   inherit (pkgs.liminix.networking) address interface;
   inherit (pkgs.liminix.services) bundle;
+  inherit (pkgs) liminix;
 
   type_service = pkgs.liminix.lib.types.service;
 
@@ -41,11 +42,25 @@ in {
           };
         '';
       };
+      makeTargets = mkOption {
+        type = types.listOf types.str;
+      };
     };
   };
   config = {
+    system.outputs =
+      let k = liminix.builders.kernel.override {
+            inherit (config.kernel) config src extraPatchPhase;
+            targets = config.kernel.makeTargets;
+          };
+      in {
+        kernel = k.vmlinux;
+        zimage = k.zImage;
+      };
+
     kernel = rec {
       modular = true; # disabling this is not yet supported
+      makeTargets = ["vmlinux"];
       config = {
         IKCONFIG = "y";
         IKCONFIG_PROC = "y";

modules/outputs.nix

@@ -99,26 +99,18 @@ in
   };
   config = {
     system.outputs = rec {
-      kernel = liminix.builders.kernel.override {
-        inherit (config.kernel) config src extraPatchPhase;
-      };
-      zimage = liminix.builders.kernel.override {
-        targets = ["arch/arm/boot/zImage"];
-        inherit (config.kernel) config src extraPatchPhase;
-      };
       dtb = liminix.builders.dtb {
         inherit (config.boot) commandLine;
         dts = config.hardware.dts.src;
         includes = config.hardware.dts.includes ++ [
-          "${kernel.headers}/include"
+          "${o.kernel.headers}/include"
         ];
       };
       uimage = liminix.builders.uimage {
         commandLine = concatStringsSep " " config.boot.commandLine;
         inherit (config.hardware) loadAddress entryPoint;
         inherit (config.boot) imageFormat;
-        inherit kernel;
-        inherit dtb;
+        inherit (o) kernel dtb;
       };
       rootdir =
         let

modules/outputs/tftpboot.nix

@@ -116,10 +116,9 @@ in {
               else "tftpboot $(hex $rootfsStart) result/rootfs"
             }; tftpboot $(hex $dtbStart) result/dtb
             ${if cfg.compressRoot
-              then "lzmadec $(hex $rootfsLzStart)  $(hex $rootfsStart)"
+              then "lzmadec $(hex $rootfsLzStart)  $(hex $rootfsStart); "
               else ""
-             }
-            ${bootCommand} $(hex $imageStart) - $(hex $dtbStart)
+             } ${bootCommand} $(hex $imageStart) - $(hex $dtbStart)
             EOF
          '';
 

overlay.nix

@@ -252,17 +252,13 @@ extraPkgs // {
    '';
   };
 
-  # gnufdisk = prev.gnufdisk.override {
-  #   guile = null;
-  # };
-
-  # util-linux = prev.util-linux.override {
-  #   ncursesSupport = false;
-  #   pamSupport = false;
-  #   systemdSupport = false;
-  #   nlsSupport = false;
-  #   translateManpages = false;
-  #   capabilitiesSupport = false;
-  # };
+  util-linux = prev.util-linux.override {
+    ncursesSupport = false;
+    pamSupport = false;
+    systemdSupport = false;
+    nlsSupport = false;
+    translateManpages = false;
+    capabilitiesSupport = false;
+  };
 
 }

pkgs/default.nix

@@ -104,4 +104,6 @@ in {
   anoia = callPackage ./anoia {};
 
   levitate = callPackage ./levitate {};
+
+  libubootenv = callPackage ./libubootenv {};
 }

pkgs/kernel/default.nix

@@ -13,6 +13,7 @@ let
   writeConfig = import ./write-kconfig.nix { inherit lib writeText; };
   kconfigFile = writeConfig "kconfig" config;
   arch = stdenv.hostPlatform.linuxArch;
+  targetNames =  map baseNameOf targets;
   inherit lib; in
 stdenv.mkDerivation rec {
   name = "kernel";
@@ -35,7 +36,7 @@ stdenv.mkDerivation rec {
 
   dontStrip = true;
   dontPatchELF = true;
-  outputs = ["out" "headers" "modulesupport"];
+  outputs = ["out" "headers" "modulesupport"] ++ targetNames;
   phases = [
     "unpackPhase"
     "butcherPkgconfig"
@@ -92,12 +93,13 @@ stdenv.mkDerivation rec {
   '';
 
   buildPhase = ''
-    make ${lib.concatStringsSep " " (map baseNameOf targets)} modules_prepare -j$NIX_BUILD_CORES
+    make ${lib.concatStringsSep " " targetNames} modules_prepare -j$NIX_BUILD_CORES
   '';
 
   installPhase = ''
     ${CROSS_COMPILE}strip -d vmlinux
-    cp ${lib.concatStringsSep " " targets} $out
+    ${lib.concatStringsSep "\n" (map (f: "cp ${f} \$${baseNameOf f}") targets)}
+    cp vmlinux $out
     mkdir -p $headers
     cp -a include .config $headers/
     mkdir -p $modulesupport

pkgs/libubootenv/Makefile

@@ -0,0 +1,6 @@
+CFLAGS=$(INC) -D_LINUX_TYPES_H -D_LINUX_STRING_H_
+
+fw_printenv: fw_env_main.o fw_env.o \
+        crc32.o ctype.o linux_string.o \
+        env_attr.o env_flags.o
+	$(CC) -o $@ $^

pkgs/libubootenv/default.nix

@@ -0,0 +1,17 @@
+{ stdenv
+, cmake
+, zlib
+, libyaml
+, fetchFromGitHub
+} :
+stdenv.mkDerivation {
+  name = "libubootenv";
+  src = fetchFromGitHub {
+    owner = "sbabic";
+    repo = "libubootenv";
+    rev = "3f4d15e36ceb58085b08dd13f3f2788e9299877b"; # v0.3.5
+    hash = "sha256-i7gUb1A6FTOBCpympQpndhOG9pCDA4P0iH7ZNBqo+PA=";
+  };
+  buildInputs = [ zlib libyaml ];
+  nativeBuildInputs = [ cmake ];
+}