nixos: config.genode.boot.storeBackend is "fs" or "memory"

Make the config.genode.boot.storeBackend option a choice between
a traditional file-system or memory-backed file-system image. Fix
GRUB booting when using a file-system store.

The nova-ahci test shows that this is working.

nixos-modules/file-systems.nix

@@ -7,7 +7,7 @@ with lib; {
 
         device = lib.mkOption { type = types.int; };
 
-        driver = lib.mkOption { type = types.enum [ "ahci" ]; };
+        driver = lib.mkOption { type = types.enum [ "ahci" "usb" ]; };
 
         partition = lib.mkOption { type = types.ints.positive; };
 
@@ -24,6 +24,9 @@ with lib; {
 
     hardware.genode.ahci.enable =
       any (fs: fs.block.driver == "ahci") (attrValues config.fileSystems);
+
+    hardware.genode.usb.storage.enable =
+      any (fs: fs.block.driver == "usb") (attrValues config.fileSystems);
   };
 
 }

nixos-modules/genode-core.nix

@@ -98,40 +98,28 @@ in {
       };
 
       storeBackend = mkOption {
-        type = types.enum [ "ahci" "tarball" "usb" ]; # "parent"?
-        default = "tarball";
+        type = types.enum [ "fs" "memory" ]; # "parent"?
+        default = "memory";
         description = ''
           Backend for the initial /nix/store file-system.
 
           <variablelist>
-
             <varlistentry>
-              <term><literal>ahci</literal></term>
+              <term>
+                <literal>fs</literal>
+              </term>
               <listitem>
-                <para>
-                  An EXT2 file-system backed by SATA storage.
-                </para>
+                <para>Store backed by a File_system session.</para>
               </listitem>
             </varlistentry>
-
             <varlistentry>
-              <term><literal>tarball</literal></term>
+              <term>
+                <literal>tarball</literal>
+              </term>
               <listitem>
-                <para>
-                  An in-memory tarball.
-                </para>
+                <para>An in-memory tarball.</para>
               </listitem>
             </varlistentry>
-
-            <varlistentry>
-              <term><literal>usb</literal></term>
-              <listitem>
-                <para>
-                  An EXT2 file-system backed by USB storage.
-                </para>
-              </listitem>
-            </varlistentry>
-
           </variablelist>
         '';
       };
@@ -198,12 +186,12 @@ in {
     }];
 
     genode.core.basePackages =
-      lib.optional (config.genode.boot.storeBackend != "tarball")
+      lib.optional (config.genode.boot.storeBackend != "memory")
       pkgs.genodePackages.part_block;
 
     genode.core.children =
       # Component to steer the store_fs to a specific partition
-      (if config.genode.boot.storeBackend != "tarball" then {
+      (if config.genode.boot.storeBackend != "memory" then {
         part_block.configFile = builtins.toFile "part_block.dhall" ''
           let Genode = env:DHALL_GENODE
 
@@ -236,7 +224,7 @@ in {
           store_fs.configFile = let
 
             storeVfsConfig =
-              if config.genode.boot.storeBackend == "tarball" then ''
+              if config.genode.boot.storeBackend == "memory" then ''
                 VFS.vfs [ VFS.leafAttrs "tar" (toMap { name = "${config.system.build.tarball.fileName}.tar" }) ]
               '' else
                 let
@@ -252,9 +240,8 @@ in {
               rumpExt2 =
                 "Init.Resources::{ caps = 256, ram = Genode.units.MiB 16 }";
             in {
-              ahci = rumpExt2;
-              tarball = "Init.Resources.default";
-              usb = rumpExt2;
+              fs = rumpExt2;
+              memory = "Init.Resources.default";
             }.${config.genode.boot.storeBackend};
 
             persistencePolicies = lib.mapAttrsToList (name: _: ''
@@ -316,9 +303,8 @@ in {
         "${config.system.build.tarball}/tarball/${config.system.build.tarball.fileName}.tar";
 
       storeBackendInputs = {
-        ahci = [ pkgs.genodePackages.rump ];
-        tarball = [ config.system.build.tarball ];
-        usb = [ pkgs.genodePackages.rump ];
+        fs = [ pkgs.genodePackages.rump ];
+        memory = [ config.system.build.tarball ];
       }.${config.genode.boot.storeBackend};
 
       coreInputs = with builtins;
@@ -422,19 +408,15 @@ in {
       bootDriveImage = import ./lib/make-bootable-image.nix {
         inherit config pkgs espImage storeFsImage;
       };
-    in lib.mkIf (config.genode.boot.storeBackend != "tarball") bootDriveImage;
+    in lib.mkIf (config.genode.boot.storeBackend != "memory") bootDriveImage;
 
-    virtualisation.useBootLoader = config.genode.boot.storeBackend != "tarball";
+    virtualisation.useBootLoader = config.genode.boot.storeBackend != "memory";
 
     virtualisation.qemu.options =
       let blockCommon = [ "-bios ${pkgs.buildPackages.OVMF.fd}/FV/OVMF.fd" ];
       in {
-        tarball = [ ];
-        ahci = blockCommon;
-        usb = blockCommon ++ [
-          "-drive id=usbdisk,file=${config.system.build.bootDriveImage},if=none,readonly"
-          "-device usb-storage,drive=usbdisk"
-        ];
+        fs = blockCommon;
+        memory = [ ];
       }.${config.genode.boot.storeBackend};
 
   };

nixos-modules/hardware/usb.nix

@@ -18,9 +18,6 @@ with lib;
   config = let cfg = config.hardware.genode.usb;
   in {
 
-    hardware.genode.usb.storage.enable = config.genode.boot.storeBackend
-      == "usb";
-
     hardware.genode.usb.enable = cfg.storage.enable;
 
     hardware.genode.platform.policies = lib.optional cfg.enable
@@ -118,7 +115,10 @@ with lib;
     virtualisation.qemu.options = lib.optional cfg.enable
       (lib.optional (pkgs.stdenv.isi686 || pkgs.stdenv.isx86_64) "-usb"
         ++ lib.optional (pkgs.stdenv.isAarch32 || pkgs.stdenv.isAarch64)
-        "-device usb-ehci,id=usb0");
+        "-device usb-ehci,id=usb0") ++ lib.optional cfg.storage.enable [
+          "-drive id=usbdisk,file=${config.system.build.bootDriveImage},if=none,readonly"
+          "-device usb-storage,drive=usbdisk"
+        ];
 
   };
 

nixos-modules/lib/make-ext2-fs.nix

@@ -23,6 +23,12 @@ in pkgs.stdenv.mkDerivation {
     # Create nix/store before copying path
     mkdir -p ./rootImage/boot/grub ./rootImage/nix/store
 
+    cat > extraPrepareConfig.sh <<< '${config.boot.loader.grub.extraPrepareConfig}'
+    substituteInPlace extraPrepareConfig.sh \
+      --replace '${pkgs.coreutils}' '${pkgs.buildPackages.coreutils}' \
+      --replace '@bootPath@' './rootImage/boot'
+    source extraPrepareConfig.sh
+
     cat <<EOF > ./rootImage/boot/grub/grub.cfg
     set timeout=3
     set default=0

nixos-modules/nova.nix

@@ -31,7 +31,7 @@ in {
   };
 
   genode.boot.storePaths =
-    lib.optional (config.genode.boot.storeBackend != "tarball") bootDir;
+    lib.optional (config.genode.boot.storeBackend != "memory") bootDir;
 
   virtualisation.qemu.options =
     lib.optionals (!config.virtualisation.useBootLoader) [
@@ -52,9 +52,9 @@ in {
       menuentry 'Genode on NOVA' {
         insmod multiboot2
         insmod gzio
-        multiboot2 /bender.gz serial_fallback
-        module2 /hypervisor.gz hypervisor iommu logmem novga novpid serial
-        module2 /image.elf.gz image.elf
+        multiboot2 /boot/bender.gz serial_fallback
+        module2 /boot/hypervisor.gz hypervisor iommu logmem novga novpid serial
+        module2 /boot/image.elf.gz image.elf
       }
     '';
     extraFiles = {

tests/ahci.nix

@@ -6,6 +6,7 @@
       device = 0;
       partition = 1;
     };
+    genode.boot.storeBackend = "fs";
     genode.init.children.hello = {
       inputs = [ pkgs.hello pkgs.genodePackages.vfs.lib ];
       configFile = pkgs.writeText "ahci-hello.child.dhall" ''