Merge pull request #151633 from wucke13/sd-image-experiment

honor `sdImage.compressImage` also in the build process

nixos/lib/make-ext4-fs.nix

@@ -78,6 +78,15 @@ pkgs.stdenv.mkDerivation {
       # get rid of the unnecessary slack here--but see
       # https://github.com/NixOS/nixpkgs/issues/125121 for caveats.
 
+      # shrink to fit
+      resize2fs -M $img
+
+      # Add 16 MebiByte to the current_size
+      new_size=$(dumpe2fs -h $img | awk -F: \
+        '/Block count/{count=$2} /Block size/{size=$2} END{print (count*size+16*2**20)/size}')
+
+      resize2fs $img $new_size
+
       if [ ${builtins.toString compressImage} ]; then
         echo "Compressing image"
         zstd -v --no-progress ./$img -o $out

nixos/modules/installer/sd-card/sd-image.nix

@@ -18,7 +18,7 @@ with lib;
 let
   rootfsImage = pkgs.callPackage ../../../lib/make-ext4-fs.nix ({
     inherit (config.sdImage) storePaths;
-    compressImage = true;
+    compressImage = config.sdImage.compressImage;
     populateImageCommands = config.sdImage.populateRootCommands;
     volumeLabel = "NIXOS_SD";
   } // optionalAttrs (config.sdImage.rootPartitionUUID != null) {
@@ -174,7 +174,8 @@ in
     mtools, libfaketime, util-linux, zstd }: stdenv.mkDerivation {
       name = config.sdImage.imageName;
 
-      nativeBuildInputs = [ dosfstools e2fsprogs mtools libfaketime util-linux zstd ];
+      nativeBuildInputs = [ dosfstools e2fsprogs libfaketime mtools util-linux ]
+      ++ lib.optional config.sdImage.compressImage zstd;
 
       inherit (config.sdImage) imageName compressImage;
 
@@ -189,14 +190,18 @@ in
           echo "file sd-image $img" >> $out/nix-support/hydra-build-products
         fi
 
+        root_fs=${rootfsImage}
+        ${lib.optionalString config.sdImage.compressImage ''
+        root_fs=./root-fs.img
         echo "Decompressing rootfs image"
-        zstd -d --no-progress "${rootfsImage}" -o ./root-fs.img
+        zstd -d --no-progress "${rootfsImage}" -o $root_fs
+        ''}
 
         # Gap in front of the first partition, in MiB
         gap=${toString config.sdImage.firmwarePartitionOffset}
 
         # Create the image file sized to fit /boot/firmware and /, plus slack for the gap.
-        rootSizeBlocks=$(du -B 512 --apparent-size ./root-fs.img | awk '{ print $1 }')
+        rootSizeBlocks=$(du -B 512 --apparent-size $root_fs | awk '{ print $1 }')
         firmwareSizeBlocks=$((${toString config.sdImage.firmwareSize} * 1024 * 1024 / 512))
         imageSize=$((rootSizeBlocks * 512 + firmwareSizeBlocks * 512 + gap * 1024 * 1024))
         truncate -s $imageSize $img
@@ -214,7 +219,7 @@ in
 
         # Copy the rootfs into the SD image
         eval $(partx $img -o START,SECTORS --nr 2 --pairs)
-        dd conv=notrunc if=./root-fs.img of=$img seek=$START count=$SECTORS
+        dd conv=notrunc if=$root_fs of=$img seek=$START count=$SECTORS
 
         # Create a FAT32 /boot/firmware partition of suitable size into firmware_part.img
         eval $(partx $img -o START,SECTORS --nr 1 --pairs)