WIP generate bootable disk image with partition table

modules/ext4fs.nix

@@ -30,7 +30,7 @@ in
         } ''
           cp -a ${o.rootfsFiles} tmp
           ${if config.boot.loader.extlinux.enable
-            then "(cd tmp && ln -s ${o.extlinux} boot)"
+            then "(cd tmp && chmod -R +w . && rmdir boot && cp -a ${o.extlinux} boot)"
             else ""
           }
           size=$(du -s --apparent-size --block-size 1024 tmp |cut -f1)

modules/outputs/diskimage.nix

@@ -0,0 +1,52 @@
+{
+  config
+, pkgs
+, lib
+, ...
+}:
+let
+  inherit (lib) mkOption types concatStringsSep;
+  o = config.system.outputs;
+  phram_address = lib.toHexString (config.hardware.ram.startAddress + 256 * 1024 * 1024);
+in {
+#  imports = [ ./flashimage.nix ];
+  options.system.outputs = {
+    diskimage = mkOption {
+      type = types.package;
+      description = ''
+        diskimage
+        *********
+
+        This creates a disk image file with a partition table containing
+        the contents of ``outputs.rootfs`` as its only partition.
+      '';
+    };
+    vmdisk = mkOption {  type = types.package; };
+  };
+
+  config = {
+    system.outputs = {
+      diskimage =
+        let
+          o = config.system.outputs;
+        in pkgs.runCommand "diskimage" {
+          depsBuildBuild = [ pkgs.pkgsBuildBuild.util-linux ];
+        } ''
+          # leave 4 sectors at start for partition table
+          # and alignment to 2048 bytes (does that help?)
+          dd if=${o.rootfs} of=$out bs=512 seek=4 conv=sync
+          echo '4,-,L,*' | sfdisk $out
+        '';
+      vmdisk = pkgs.runCommand "vmdisk" {} ''
+        mkdir $out
+        cd $out
+        ln -s ${o.diskimage} ./diskimage
+        cat > run.sh <<EOF
+        #!${pkgs.runtimeShell}
+        ${pkgs.pkgsBuildBuild.run-liminix-vm}/bin/run-liminix-vm  --arch ${pkgs.stdenv.hostPlatform.qemuArch} --u-boot ${pkgs.ubootQemuArm}/u-boot.bin --phram-address 0x${phram_address} --disk-image ${o.diskimage} /dev/null /dev/null
+        EOF
+        chmod +x run.sh
+      '';
+    };
+  };
+}

modules/outputs/extlinux.nix

@@ -20,17 +20,18 @@ in {
     system.outputs.extlinux = pkgs.runCommand "extlinux" {} ''
       mkdir $out
       cd $out
-      ln -s ${o.dtb} dtb
-      ln -s ${o.initramfs} initramfs
+      # cp {o.dtb} dtb
+      cp ${o.initramfs} initramfs
       gzip -9f < ${o.kernel} > kernel.gz
-      cat > extlinux.conf << _EOF
+      mkdir extlinux
+      cat > extlinux/extlinux.conf << _EOF
       menu title Liminix
       timeout 100
       label Liminix
-        kernel kernel.gz
-        initrd initramfs
-        fdt dtb
+        kernel /boot/kernel.gz
+        initrd /boot/initramfs
         append ${cmdline}
+        # fdt /boot/dtb
       _EOF
     '';
   };