Add 'tftpbootubi' output: emits a ubifs rootfs image and tftpbootable kernel

modules/all-modules.nix

@@ -25,6 +25,7 @@
    ./outputs/kexecboot.nix
    ./outputs/mtdimage.nix
    ./outputs/tftpboot.nix
+   ./outputs/tftpbootubi.nix
    ./outputs/ubifs.nix
    ./outputs/ubimage.nix
    ./outputs/vmroot.nix

modules/outputs/tftpbootubi.nix

@@ -0,0 +1,155 @@
+{
+  config
+, pkgs
+, lib
+, ...
+}:
+let
+  inherit (lib) mkOption types concatStringsSep;
+  cfg = config.boot.tftp;
+  hw = config.hardware;
+  arch = pkgs.stdenv.hostPlatform.linuxArch;
+in {
+  imports = [ ../ramdisk.nix ];
+  options.boot.tftp = {
+    freeSpaceBytes = mkOption {
+      type = types.int;
+      default = 0;
+    };
+    kernelFormat = mkOption {
+      type = types.enum [ "zimage" "uimage" ];
+      default = "uimage";
+    };
+    compressRoot = mkOption {
+      type = types.bool;
+      default = false;
+    };
+    appendDTB = mkOption {
+      type = types.bool;
+      default = false;
+    };
+  };
+  options.system.outputs = {
+    tftpbootubi = mkOption {
+      type = types.package;
+      description = ''
+        tftpbootubi
+        ***********
+
+        This output is intended for developing on a new device that
+        uses a UBI layout / ubifs root filesystem, but which cannot
+        load the kernel directly from inside the ubi image.
+        It assumes you have a serial connection and a
+        network connection to the device and that your
+        build machine is running a TFTP server.
+
+        The output is a directory containing kernel and
+        a ubifs root filesystem image. The ubifs image will currently
+        need to be manually written from a booted system (e.g. with
+        OpenWRT), using ubimkvol, ubiupdatevol, etc. Once that is done
+        the kernel can be booted over tftp; the script :file:`boot.scr`
+        contains U-Boot commands that will load the kernel etc into memory and
+        boot it directly.
+      '';
+    };
+  };
+  config = {
+    boot.ramdisk.enable = true;
+
+    system.outputs = rec {
+      rootfs = config.system.outputs.rootubifs;
+      tftpbootubi =
+        let
+          o = config.system.outputs;
+          image = let choices = {
+            uimage = o.uimage;
+            zimage = o.zimage;
+          }; in choices.${cfg.kernelFormat};
+          bootCommand = let choices = {
+            uimage = "bootm";
+            zimage = "bootz";
+          }; in choices.${cfg.kernelFormat};
+
+          cmdline = concatStringsSep " " config.boot.commandLine;
+          objcopy = "${pkgs.stdenv.cc.bintools.targetPrefix}objcopy";
+          stripAndZip = ''
+            ${objcopy} -O binary -R .reginfo -R .notes -R .note -R .comment -R .mdebug -R .note.gnu.build-id -S vmlinux.elf vmlinux.bin
+            rm -f vmlinux.bin.lzma ; lzma -k -z  vmlinux.bin
+          '';
+        in
+          pkgs.runCommand "tftpbootubi" { nativeBuildInputs = with pkgs.pkgsBuildBuild; [ lzma dtc pkgs.stdenv.cc ubootTools ];  } ''
+            mkdir $out
+            cd $out
+            binsize() { local s=$(stat -L -c %s $1); echo $(($s + 0x1000 &(~0xfff))); }
+            binsize64k() { local s=$(stat -L -c %s $1); echo $(($s + 0x10000 &(~0xffff))); }
+            hex() { printf "0x%x" $1; }
+
+            rootfsStart=${toString cfg.loadAddress}
+            rootfsSize=$(binsize64k ${o.rootfs} )
+            rootfsSize=$(($rootfsSize + ${toString cfg.freeSpaceBytes} ))
+
+            ln -s ${o.manifest} manifest
+            ln -s ${o.kernel} vmlinux  # handy for gdb
+
+            # if we are transferring kernel and dtb separately, the
+            # dtb has to precede the kernel in ram, because zimage
+            # decompression code will assume that any memory after the
+            # end of the kernel is free
+
+            dtbStart=$(($rootfsStart + $rootfsSize))
+            ${if cfg.compressRoot
+              then ''
+                lzma -z9cv ${o.rootfs} > rootfs.lz
+                rootfsLzStart=$dtbStart
+                rootfsLzSize=$(binsize rootfs.lz)
+                dtbStart=$(($dtbStart + $rootfsLzSize))
+              ''
+              else ''
+                ln -s ${o.rootfs} rootfs
+              ''
+             }
+
+            cat ${o.dtb} > dtb
+            cmd="liminix ${cmdline}";
+
+            fdtput -t s dtb /chosen ${config.boot.commandLineDtbNode} "$cmd"
+
+            dtbSize=$(binsize ./dtb )
+
+            ${if cfg.appendDTB then ''
+              imageStart=$dtbStart
+              # re-package image with updated dtb
+              cat ${o.kernel} > vmlinux.elf
+              ${objcopy} --update-section .appended_dtb=dtb vmlinux.elf
+              ${stripAndZip}
+              mkimage -A ${arch} -O linux -T kernel -C lzma -a $(hex ${toString hw.loadAddress}) -e $(hex ${toString hw.entryPoint}) -n '${lib.toUpper arch} Liminix Linux tftpboot' -d vmlinux.bin.lzma image
+              # dtc -I dtb -O dts -o /dev/stdout dtb | grep -A10 chosen ; exit 1
+              tftpcmd="tftpboot $(hex $imageStart) result/image "
+              bootcmd="bootm $(hex $imageStart)"
+            '' else ''
+              imageStart=$(($dtbStart + $dtbSize))
+              tftpcmd="tftpboot $(hex $imageStart) result/image; tftpboot $(hex $dtbStart) result/dtb "
+              ln -s ${image} image
+              bootcmd="${bootCommand} $(hex $imageStart) - $(hex $dtbStart)"
+            ''}
+
+            cat > boot.scr << EOF
+            setenv serverip ${cfg.serverip}
+            setenv ipaddr ${cfg.ipaddr}
+            ${
+              if cfg.compressRoot
+              then "tftpboot $(hex $rootfsLzStart) result/rootfs.lz"
+              else "tftpboot $(hex $rootfsStart) result/rootfs"
+            }; $tftpcmd
+            ${if cfg.compressRoot
+              then "lzmadec $(hex $rootfsLzStart)  $(hex $rootfsStart); "
+              else ""
+             } $bootcmd
+            EOF
+         '';
+
+    };
+  };
+}
+
+# vim: set ts=2 sw=2 sta et: