diff options
| -rw-r--r-- | nixos/modules/virtualisation/qemu-vm.nix | 59 |
1 files changed, 56 insertions, 3 deletions
diff --git a/nixos/modules/virtualisation/qemu-vm.nix b/nixos/modules/virtualisation/qemu-vm.nix index c5f71b249a6..6af5848b168 100644 --- a/nixos/modules/virtualisation/qemu-vm.nix +++ b/nixos/modules/virtualisation/qemu-vm.nix @@ -122,6 +122,12 @@ let TMPDIR=$(mktemp -d nix-vm.XXXXXXXXXX --tmpdir) fi + ${lib.optionalString cfg.useNixStoreImage + '' + # Create a writable copy/snapshot of the store image. + ${qemu}/bin/qemu-img create -f qcow2 -F qcow2 -b ${storeImage}/nixos.qcow2 "$TMPDIR"/store.img + ''} + # Create a directory for exchanging data with the VM. mkdir -p "$TMPDIR/xchg" @@ -263,6 +269,18 @@ let '' # */ ); + storeImage = import ../../lib/make-disk-image.nix { + inherit pkgs config lib; + additionalPaths = [ regInfo ]; + format = "qcow2"; + onlyNixStore = true; + partitionTableType = "none"; + installBootLoader = false; + diskSize = "auto"; + additionalSpace = "0M"; + copyChannel = false; + }; + in { @@ -608,6 +626,20 @@ in }; }; + virtualisation.useNixStoreImage = + mkOption { + type = types.bool; + default = false; + description = '' + Build and use a disk image for the Nix store, instead of + accessing the host's one through 9p. + + For applications which do a lot of reads from the store, + this can drastically improve performance, but at the cost of + disk space and image build time. + ''; + }; + virtualisation.useBootLoader = mkOption { type = types.bool; @@ -762,9 +794,18 @@ in virtualisation.pathsInNixDB = [ config.system.build.toplevel ]; virtualisation.sharedDirectories = { - nix-store = { source = "/nix/store"; target = "/nix/store"; }; - xchg = { source = ''"$TMPDIR"/xchg''; target = "/tmp/xchg"; }; - shared = { source = ''"''${SHARED_DIR:-$TMPDIR/xchg}"''; target = "/tmp/shared"; }; + nix-store = mkIf (!cfg.useNixStoreImage) { + source = builtins.storeDir; + target = "/nix/store"; + }; + xchg = { + source = ''"$TMPDIR"/xchg''; + target = "/tmp/xchg"; + }; + shared = { + source = ''"''${SHARED_DIR:-$TMPDIR/xchg}"''; + target = "/tmp/shared"; + }; }; virtualisation.qemu.networkingOptions = @@ -815,6 +856,11 @@ in driveExtraOpts.cache = "writeback"; driveExtraOpts.werror = "report"; }] + (mkIf cfg.useNixStoreImage [{ + name = "nix-store"; + file = ''"$TMPDIR"/store.img''; + deviceExtraOpts.bootindex = if cfg.useBootLoader then "3" else "2"; + }]) (mkIf cfg.useBootLoader [ # The order of this list determines the device names, see # note [Disk layout with `useBootLoader`]. @@ -865,6 +911,13 @@ in options = [ "mode=1777" "strictatime" "nosuid" "nodev" "size=${toString config.boot.tmpOnTmpfsSize}" ]; }; + "/nix/${if cfg.writableStore then ".ro-store" else "store"}" = + mkIf cfg.useNixStoreImage + { device = "${lookupDriveDeviceName "nix-store" cfg.qemu.drives}"; + neededForBoot = true; + options = [ "ro" ]; + }; + "/nix/.rw-store" = mkIf (cfg.writableStore && cfg.writableStoreUseTmpfs) { fsType = "tmpfs"; options = [ "mode=0755" ]; |