diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index 1d519e9..78c7aad 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -144,6 +144,59 @@ jobs:
             git+https://github.com/antmicro/tuttest.git@c44309e0365c54759fb36864fb77bf8b347bd647
           repos: https://github.com/antmicro/pyrav4l2.git pyrav4l2
 
+  riscv64-shared-dirs-test:
+    runs-on: ubuntu-latest
+    needs: send-to-releases
+    if: ${{ !failure() && !github.event.act }}
+    steps:
+      - uses: actions/checkout@v3
+
+      - name: prepare shared directiories
+        run: mkdir shared_dir shared_dir2
+
+      - name: test
+        uses: ./
+        with:
+          rootfs-size: +128M
+          shared-dirs: |
+            shared_dir /home/shared_dir
+            shared_dir2 /home/shared_dir2
+          renode-run: |
+            echo "shared-dirs-test" > shared_dir/f.txt
+            echo "shared-dirs-test2" > shared_dir2/f.txt
+
+      - name: read shared directories
+        run: |
+          $([ "$(cat shared_dir/f.txt)" = "shared-dirs-test" ])
+          $([ "$(cat shared_dir2/f.txt)" = "shared-dirs-test2" ])
+
+  arm32-shared-dirs-test:
+    runs-on: ubuntu-latest
+    needs: send-to-releases
+    if: ${{ !failure() && !github.event.act }}
+    steps:
+      - uses: actions/checkout@v3
+
+      - name: prepare shared directiories
+        run: mkdir shared_dir shared_dir2
+
+      - name: test
+        uses: ./
+        with:
+          arch: arm32
+          rootfs-size: +128M
+          shared-dirs: |
+            shared_dir /home/shared_dir
+            shared_dir2 /home/shared_dir2
+          renode-run: |
+            echo "shared-dirs-test" > shared_dir/f.txt
+            echo "shared-dirs-test2" > shared_dir2/f.txt
+
+      - name: read shared directories
+        run: |
+          $([ "$(cat shared_dir/f.txt)" = "shared-dirs-test" ])
+          $([ "$(cat shared_dir2/f.txt)" = "shared-dirs-test2" ])
+
   arm32-test:
     runs-on: ubuntu-latest
     needs: send-to-releases
diff --git a/README.md b/README.md
index 822ec33..1a3b35d 100644
--- a/README.md
+++ b/README.md
@@ -17,7 +17,7 @@ This is achieved by running an emulated Linux system inside [Renode](https://ren
 
 ### OS configuration
 
-- [`rootfs-size`](#rootfs-size) - Set the size of the rootfs image. Default: `auto`
+- [`rootfs-size`](#rootfs-size) - Set the size of the rootfs image. Default: `auto`.
 - [`image-type`](#image) - `native` or `docker`. Read about the differences in the [image section](#image)
 - [`image`](#image) - URL path to a Linux rootfs `tar.xz` archive for the specified architecture or a Docker image identifier. If not specified, the action will use the default one. See releases for examples
 - [`tasks`](#tasks) - Allows you to change the way the system is initialized. See [Tasks](#tasks) for more details.
@@ -132,7 +132,9 @@ We are working on adding `arm64` support.
 
 You can specify many directories that will be added to the rootfs. All files from these directories will be available in the specified target directories.
 
-In the following example, files from the `project-files` directory will be extracted to the `/opt/project` directory. If no destination directory is specified, the files will be extracted to `/home`.
+In the following example, files from the `project-files` directory will be extracted to the `/opt/project` directory. If no destination directory is specified, the files will be extracted to `/home`.  
+
+At the end of the action contents of the shared directories will be copied back from the mounted filesystem.
 
 ```yaml
 - uses: antmicro/renode-linux-runner-action@v1
@@ -226,7 +228,7 @@ If you need additional software, you can mount your own filesystem. More informa
 
 ## Rootfs size
 
-The size of the mounted rootfs can be specified with the `rootfs-size` parameter. The parameter accepts sizes in bytes (e.g. `1000000000`), kilobytes (e.g. `50000K`), megabytes (e.g. `512M`) or gigabytes (e.g. `1G`). The default `rootfs-size` value is `auto`; with this setting the size is calculated automatically.
+The size of the mounted rootfs can be specified with the `rootfs-size` parameter. The parameter accepts sizes in bytes (e.g. `1000000000`), kilobytes (e.g. `50000K`), megabytes (e.g. `512M`) or gigabytes (e.g. `1G`). The default `rootfs-size` value is `auto`; with this setting the size is calculated automatically. Preceding the value with `+` sign (e.g. `+value`) sets the size to `auto` + `value`.
 
 ```yaml
 - uses: antmicro/renode-linux-runner-action@v1
diff --git a/action/device/hifive_unleashed/init.resc b/action/device/hifive_unleashed/init.resc
index 94a77cf..f60a288 100644
--- a/action/device/hifive_unleashed/init.resc
+++ b/action/device/hifive_unleashed/init.resc
@@ -6,7 +6,7 @@ machine LoadPlatformDescription @action/device/hifive_unleashed/platform.repl
 
 # rootfs
 machine LoadPlatformDescriptionFromString 'virtio: Storage.VirtIOBlockDevice @ sysbus 0x100d0000 { IRQ -> plic@50 }'
-virtio LoadImage @images/rootfs.img
+virtio LoadImage @images/rootfs.img true
 
 showAnalyzer uart0
 e51 LogFunctionNames true
diff --git a/action/device/zynq_7000/init.resc b/action/device/zynq_7000/init.resc
index 021c99f..802a520 100644
--- a/action/device/zynq_7000/init.resc
+++ b/action/device/zynq_7000/init.resc
@@ -19,7 +19,7 @@ ttc1 Frequency 33333333
 
 # rootfs
 machine LoadPlatformDescriptionFromString 'virtio: Storage.VirtIOBlockDevice @ sysbus 0xe0104000 { IRQ -> gic@63 }'
-virtio LoadImage @images/rootfs.img
+virtio LoadImage @images/rootfs.img true
 
 # This setting increases emulation speed, thus mitigates networks errors and speedup user scripts.
 machine SetAdvanceImmediately true
diff --git a/action/images.py b/action/images.py
index 85a3faa..bda1e24 100644
--- a/action/images.py
+++ b/action/images.py
@@ -105,6 +105,36 @@ def prepare_kernel_and_initramfs(kernel: str):
         error("Kernel not found! Action expects Image or vmlinux file.")
 
 
+def rootfs_size(size_str: str) -> int:
+    """
+    Returns rootfs size
+
+    Parameters
+    ----------
+    size_str: str
+        rootfs-size action parameter value
+    """
+
+    units = {
+        "B": 1,
+        "K": 1024,
+        "M": 1024**2,
+        "G": 1024**3
+    }
+
+    if size_str == "auto" or size_str.startswith("+"):
+        size = 0
+        for path, _, files in os.walk("images/rootfs"):
+            for f in files:
+                fp = os.path.join(path, f)
+                if not os.path.islink(fp):
+                    size += os.path.getsize(fp)
+
+        additional_size = int(size_str[:-1]) * units[size_str[-1]] if size_str.startswith("+") and size_str[-1] in units else 0
+        return max(size * 2, 5 * 10**7) + additional_size
+    return int(size_str)
+
+
 def burn_rootfs_image(
         user_directory: str,
         image: str,
@@ -185,18 +215,8 @@ def burn_rootfs_image(
             dirs_exist_ok=True
         )
 
-    if image_size == "auto":
-        size = 0
-        for path, _, files in os.walk("images/rootfs"):
-            for f in files:
-                fp = os.path.join(path, f)
-                if not os.path.islink(fp):
-                    size += os.path.getsize(fp)
-
-        image_size = f'{max(size * 2, 5 * 10**7)}'
     try:
-
-        run(["truncate", "images/rootfs.img", "-s", image_size], check=True)
+        run(["truncate", "images/rootfs.img", "-s", f"{rootfs_size(image_size)}"], check=True)
         run(["mkfs.ext4", "-d", "images/rootfs", "images/rootfs.img"],
             check=True,
             stdout=DEVNULL)
diff --git a/action/run-in-renode.py b/action/run-in-renode.py
index b0e0a8d..6f0eba5 100644
--- a/action/run-in-renode.py
+++ b/action/run-in-renode.py
@@ -16,14 +16,17 @@
 from common import get_file, error, archs
 from devices import add_devices
 from dependencies import add_repos, add_packages
-from images import prepare_shared_directories, prepare_kernel_and_initramfs, burn_rootfs_image
+from images import prepare_shared_directories, prepare_kernel_and_initramfs, burn_rootfs_image, shared_directories_actions
 from dispatcher import CommandDispatcher
+from subprocess import run
 
 from datetime import datetime
 
 import sys
 import json
 import yaml
+import shutil
+import os
 
 
 DEFAULT_IMAGE_PATH = "https://github.com/{}/releases/download/{}/image-{}-default.tar.xz"
@@ -146,3 +149,12 @@ def test_task(test_task_str: str):
     dispatcher.add_task(test_task(args.get("renode-run", "")))
 
     dispatcher.evaluate()
+
+    run(["mkdir", "rootfs"], check=True)
+    run(["sudo", "mount", "images/rootfs.img", "rootfs"], check=True)
+
+    for dir in shared_directories_actions:
+        src = f"rootfs/{dir.target}"
+        dst = f"{user_directory}/{dir.host}" if not dir.host.startswith('/') else dir.host
+        if os.path.exists(src):
+            shutil.copytree(src, dst, dirs_exist_ok=True)
diff --git a/action/tasks/save_shared_dirs.yml b/action/tasks/save_shared_dirs.yml
new file mode 100644
index 0000000..0568515
--- /dev/null
+++ b/action/tasks/save_shared_dirs.yml
@@ -0,0 +1,8 @@
+name: save_shared_dirs
+shell: target
+requires: [action_test]
+echo: true
+timeout: 5
+fail-fast: false
+commands:
+  - sync
\ No newline at end of file