diff --git a/.github/workflows/basic-ci-amd64.yaml b/.github/workflows/basic-ci-amd64.yaml
index 79c938fb1e..687e99f5d9 100644
--- a/.github/workflows/basic-ci-amd64.yaml
+++ b/.github/workflows/basic-ci-amd64.yaml
@@ -88,7 +88,7 @@ jobs:
       fail-fast: false
       matrix:
         containerd_version: ['lts', 'active']
-        vmm: ['clh', 'cloud-hypervisor', 'dragonball', 'qemu', 'qemu-runtime-rs']
+        vmm: ['clh', 'cloud-hypervisor', 'dragonball', 'qemu', 'qemu-runtime-rs', 'fc-rs']
     runs-on: ubuntu-22.04
     env:
       CONTAINERD_VERSION: ${{ matrix.containerd_version }}
@@ -283,6 +283,7 @@ jobs:
           - qemu
           - cloud-hypervisor
           - qemu-runtime-rs
+          - fc-rs
     runs-on: ubuntu-22.04
     env:
       KATA_HYPERVISOR: ${{ matrix.vmm }}
diff --git a/.github/workflows/run-k8s-tests-on-free-runner.yaml b/.github/workflows/run-k8s-tests-on-free-runner.yaml
index 23b738b7b6..c212c80e1f 100644
--- a/.github/workflows/run-k8s-tests-on-free-runner.yaml
+++ b/.github/workflows/run-k8s-tests-on-free-runner.yaml
@@ -46,6 +46,8 @@ jobs:
           { vmm: qemu-runtime-rs, containerd_version: active },
           { vmm: cloud-hypervisor, containerd_version: lts },
           { vmm: cloud-hypervisor, containerd_version: active },
+          { vmm: fc-rs, containerd_version: lts, snapshotter: devmapper },
+          { vmm: fc-rs, containerd_version: active, snapshotter: devmapper },
         ]
     runs-on: ubuntu-24.04
     permissions:
@@ -61,6 +63,7 @@ jobs:
       K8S_TEST_HOST_TYPE: baremetal-no-attestation
       CONTAINER_ENGINE: containerd
       CONTAINER_ENGINE_VERSION: ${{ matrix.environment.containerd_version }}
+      SNAPSHOTTER: ${{ matrix.environment.snapshotter || '' }}
       GH_TOKEN: ${{ github.token }}
     steps:
       - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
@@ -105,6 +108,10 @@ jobs:
       - name: Deploy k8s (kubeadm)
         run: bash tests/integration/kubernetes/gha-run.sh deploy-k8s
 
+      - name: Configure snapshotter
+        if: matrix.environment.snapshotter != ''
+        run: bash tests/integration/kubernetes/gha-run.sh configure-snapshotter
+
       - name: Install `bats`
         run: bash tests/integration/kubernetes/gha-run.sh install-bats
 
diff --git a/docs/design/virtualization.md b/docs/design/virtualization.md
index 684e912b55..809209746c 100644
--- a/docs/design/virtualization.md
+++ b/docs/design/virtualization.md
@@ -275,7 +275,7 @@ Each hypervisor has a dedicated configuration file:
 |------------|----------------|-----------------|
 | QEMU |`configuration-qemu-runtime-rs.toml` |`configuration-qemu.toml` |
 | Cloud Hypervisor | `configuration-cloud-hypervisor.toml` | `configuration-clh.toml` |
-| Firecracker | `configuration-rs-fc.toml` | `configuration-fc.toml` |
+| Firecracker | `configuration-fc-rs.toml` | `configuration-fc.toml` |
 | Dragonball | `configuration-dragonball.toml` (default) | `No` |
 
 > **Note:** Configuration files are typically installed in `/opt/kata/share/defaults/kata-containers/` or  `/opt/kata/share/defaults/kata-containers/runtime-rs/` or `/usr/share/defaults/kata-containers/`.
diff --git a/src/runtime-rs/Makefile b/src/runtime-rs/Makefile
index 2da9e29e82..21df4846d9 100644
--- a/src/runtime-rs/Makefile
+++ b/src/runtime-rs/Makefile
@@ -419,7 +419,7 @@ endif
 
 ifneq (,$(FCCMD))
     KNOWN_HYPERVISORS += $(HYPERVISOR_FC)
-    CONFIG_FILE_FC = configuration-rs-fc.toml
+    CONFIG_FILE_FC = configuration-fc-rs.toml
     CONFIG_FC = config/$(CONFIG_FILE_FC)
     CONFIG_FC_IN = $(CONFIG_FC).in
     CONFIG_PATH_FC = $(abspath $(CONFDIR)/$(CONFIG_FILE_FC))
diff --git a/src/runtime-rs/README.md b/src/runtime-rs/README.md
index fe6f8e10dc..15af90bf38 100644
--- a/src/runtime-rs/README.md
+++ b/src/runtime-rs/README.md
@@ -157,7 +157,7 @@ Configuration files in `config/`:
 | `configuration-dragonball.toml.in` | Dragonball | Built-in VMM |
 | `configuration-qemu-runtime-rs.toml.in` | QEMU | Default external |
 | `configuration-cloud-hypervisor.toml.in` | Cloud Hypervisor | Modern VMM |
-| `configuration-rs-fc.toml.in` | Firecracker | Lightweight microVM |
+| `configuration-fc-rs.toml.in` | Firecracker | Lightweight microVM |
 | `configuration-remote.toml.in` | Remote | Remote hypervisor |
 | `configuration-qemu-tdx-runtime-rs.toml.in` | QEMU + TDX | Intel TDX confidential computing |
 | `configuration-qemu-snp-runtime-rs.toml.in` | QEMU + SEV-SNP | AMD SEV-SNP confidential computing |
diff --git a/src/runtime-rs/config/configuration-rs-fc.toml.in b/src/runtime-rs/config/configuration-fc-rs.toml.in
similarity index 100%
rename from src/runtime-rs/config/configuration-rs-fc.toml.in
rename to src/runtime-rs/config/configuration-fc-rs.toml.in
diff --git a/src/runtime-rs/crates/hypervisor/src/firecracker/fc_api.rs b/src/runtime-rs/crates/hypervisor/src/firecracker/fc_api.rs
index 7459814b28..4b44220295 100644
--- a/src/runtime-rs/crates/hypervisor/src/firecracker/fc_api.rs
+++ b/src/runtime-rs/crates/hypervisor/src/firecracker/fc_api.rs
@@ -3,6 +3,8 @@
 //
 //SPDX-License-Identifier: Apache-2.0
 
+use std::convert::TryFrom;
+
 use crate::{
     firecracker::{
         inner_hypervisor::{FC_AGENT_SOCKET_NAME, ROOT},
@@ -121,7 +123,8 @@ impl FcInner {
 
         let body_config: String = json!({
             "mem_size_mib": self.config.memory_info.default_memory,
-            "vcpu_count": self.config.cpu_info.default_vcpus.ceil() as u8,
+            "vcpu_count": u8::try_from(self.config.cpu_info.default_vcpus.ceil() as u64)
+                .context("vcpu_count overflows u8")?,
         })
         .to_string();
         let body_kernel: String = json!({
@@ -289,7 +292,7 @@ impl FcInner {
                 // A transport error (FC not ready yet) — retry.
                 Err(FcRequestError::Transport(e)) => {
                     debug!(sl(), "FC not reachable yet, retrying: {:?}", e);
-                    std::thread::sleep(std::time::Duration::from_millis(10));
+                    tokio::time::sleep(std::time::Duration::from_millis(10)).await;
                     continue;
                 }
                 // An HTTP-level error from FC — fail immediately with the
diff --git a/src/runtime-rs/crates/hypervisor/src/firecracker/inner.rs b/src/runtime-rs/crates/hypervisor/src/firecracker/inner.rs
index 9cf888cc80..7ed6c26e98 100644
--- a/src/runtime-rs/crates/hypervisor/src/firecracker/inner.rs
+++ b/src/runtime-rs/crates/hypervisor/src/firecracker/inner.rs
@@ -130,9 +130,11 @@ impl FcInner {
                 if !jailed {
                     if let Some(netns_path) = &netns {
                         debug!(sl(), "set netns for vmm master {:?}", &netns_path);
-                        let netns_fd = std::fs::File::open(netns_path);
-                        let _ = setns(netns_fd?.as_raw_fd(), CloneFlags::CLONE_NEWNET)
-                            .context("set netns failed");
+                        let netns_fd = std::fs::File::open(netns_path)?;
+                        setns(netns_fd.as_raw_fd(), CloneFlags::CLONE_NEWNET)
+                            .map_err(|e| std::io::Error::other(
+                                format!("setns into {:?} failed: {}", netns_path, e),
+                            ))?;
                     }
                 }
                 if let Some(label) = selinux_label.as_ref() {
diff --git a/src/runtime-rs/crates/hypervisor/src/firecracker/inner_device.rs b/src/runtime-rs/crates/hypervisor/src/firecracker/inner_device.rs
index b7b9ed7bf5..7c113c2cd6 100644
--- a/src/runtime-rs/crates/hypervisor/src/firecracker/inner_device.rs
+++ b/src/runtime-rs/crates/hypervisor/src/firecracker/inner_device.rs
@@ -33,7 +33,7 @@ impl FcInner {
                 .context("add block device"),
             DeviceType::Network(network) => {
                 // Buffer network devices and send them to FC just before InstanceStart
-                // in start_vm(). Firecracker rejects PUT /network-interfaces after the
+                // in boot_vm(). Firecracker rejects PUT /network-interfaces after the
                 // VM has started, so we must ensure they arrive before InstanceStart.
                 // This mirrors the Go runtime's batch-configuration approach.
                 //
diff --git a/tests/common.bash b/tests/common.bash
index 2257c9bcd2..5a40c33ad1 100644
--- a/tests/common.bash
+++ b/tests/common.bash
@@ -517,7 +517,7 @@ function enabling_hypervisor() {
 	declare -r CONTAINERD_SHIM_KATA="/usr/local/bin/containerd-shim-kata-${KATA_HYPERVISOR}-v2"
 
 	case "${KATA_HYPERVISOR}" in
-		dragonball|cloud-hypervisor|qemu-runtime-rs|qemu-se-runtime-rs)
+		dragonball|cloud-hypervisor|qemu-runtime-rs|qemu-se-runtime-rs|fc-rs)
 			sudo ln -sf "${KATA_DIR}/runtime-rs/bin/containerd-shim-kata-v2" "${CONTAINERD_SHIM_KATA}"
 			declare -r CONFIG_DIR="${KATA_DIR}/share/defaults/kata-containers/runtime-rs"
 			;;
@@ -536,6 +536,65 @@ function enabling_hypervisor() {
 }
 
 
+# Sets up a devmapper thin-pool and reconfigures standalone containerd to use
+# it as the default snapshotter.  Required for block-device based hypervisors
+# (e.g. Firecracker / fc-rs) that cannot use the overlayfs snapshotter.
+# Expects containerd to already be installed and /etc/containerd/config.toml
+# to exist (e.g. after `containerd config default | sudo tee ...`).
+function configure_devmapper_for_containerd() {
+	info "Configuring devmapper snapshotter for standalone containerd"
+
+	sudo mkdir -p /var/lib/containerd/devmapper
+	sudo truncate --size 10G /var/lib/containerd/devmapper/data-disk.img
+	sudo truncate --size 1G  /var/lib/containerd/devmapper/meta-disk.img
+
+	# Allocate loop devices dynamically to avoid conflicts with pre-existing ones.
+	local loop_data loop_meta
+	loop_data=$(sudo losetup --find --show /var/lib/containerd/devmapper/data-disk.img)
+	loop_meta=$(sudo losetup --find --show /var/lib/containerd/devmapper/meta-disk.img)
+	info "devmapper: data=${loop_data} meta=${loop_meta}"
+
+	local data_sectors
+	data_sectors=$(sudo blockdev --getsz "${loop_data}")
+	sudo dmsetup create contd-thin-pool \
+		--table "0 ${data_sectors} thin-pool ${loop_meta} ${loop_data} 512 32768 1 skip_block_zeroing"
+
+	# Write a complete containerd v2 config combining the kata runtime with the
+	# devmapper snapshotter.  We replace whatever was there before (both the v2
+	# config from overwrite_containerd_config and the v3 default from
+	# 'containerd config default') so the result is always correct regardless of
+	# format or prior content.
+	sudo tee /etc/containerd/config.toml <<'TOML_EOF'
+version = 2
+
+[plugins]
+  [plugins."io.containerd.grpc.v1.cri"]
+    [plugins."io.containerd.grpc.v1.cri".containerd]
+      snapshotter = "devmapper"
+      [plugins."io.containerd.grpc.v1.cri".containerd.runtimes]
+        [plugins."io.containerd.grpc.v1.cri".containerd.runtimes.runc]
+          runtime_type = "io.containerd.runc.v2"
+        [plugins."io.containerd.grpc.v1.cri".containerd.runtimes.kata]
+          runtime_type = "io.containerd.kata.v2"
+
+[plugins."io.containerd.snapshotter.v1.devmapper"]
+  pool_name = "contd-thin-pool"
+  root_path = "/var/lib/containerd/devmapper"
+  base_image_size = "4096MB"
+  discard_blocks = true
+TOML_EOF
+
+	sudo systemctl restart containerd
+
+	# Verify the plugin came up healthy
+	local dm_status
+	dm_status=$(sudo ctr plugins ls | awk '$2 ~ /^devmapper$/ { print $4 }' || true)
+	[ "${dm_status}" = "ok" ] || \
+		die "containerd devmapper snapshotter not healthy (status: '${dm_status}')"
+
+	info "devmapper snapshotter configured and healthy"
+}
+
 function check_containerd_config_for_kata() {
 	# check containerd config
 	declare -r line1="default_runtime_name = \"kata\""
diff --git a/tests/integration/kubernetes/gha-run.sh b/tests/integration/kubernetes/gha-run.sh
index 6055005d64..b9a1c8c615 100755
--- a/tests/integration/kubernetes/gha-run.sh
+++ b/tests/integration/kubernetes/gha-run.sh
@@ -80,7 +80,7 @@ EOF
 			containerd_config_file="/var/lib/rancher/k3s/agent/etc/containerd/config.toml.tmpl"
 			sudo cp /var/lib/rancher/k3s/agent/etc/containerd/config.toml "${containerd_config_file}"
 			;;
-		kubeadm)
+		kubeadm|vanilla)
 			containerd_config_file="/etc/containerd/config.toml"
 			;;
 		*) >&2 echo "${KUBERNETES} flavour is not supported"; exit 2 ;;
@@ -120,7 +120,7 @@ EOF
 	case "${KUBERNETES}" in
 		k3s)
 			sudo systemctl restart k3s ;;
-		kubeadm)
+		kubeadm|vanilla)
 			sudo systemctl restart containerd ;;
 		*) >&2 echo "${KUBERNETES} flavour is not supported"; exit 2 ;;
 	esac
diff --git a/tests/integration/nerdctl/gha-run.sh b/tests/integration/nerdctl/gha-run.sh
index 91fbff1f52..444debd08f 100755
--- a/tests/integration/nerdctl/gha-run.sh
+++ b/tests/integration/nerdctl/gha-run.sh
@@ -51,7 +51,7 @@ function install_dependencies() {
 
 	# Create the default containerd configuration
 	sudo mkdir -p /etc/containerd
-	containerd config default > sudo tee /etc/containerd/config.toml
+	containerd config default | sudo tee /etc/containerd/config.toml
 	sudo systemctl restart containerd
 }
 
@@ -106,27 +106,46 @@ function run() {
 
 	info "Running nerdctl smoke test tests using ${KATA_HYPERVISOR} hypervisor"
 
+	# fc-rs uses devmapper block devices; nerdctl must be told to use the
+	# devmapper snapshotter explicitly so images are unpacked into the pool.
+	local snapshotter_flag=""
+	if [ "${KATA_HYPERVISOR}" = "fc-rs" ]; then
+		snapshotter_flag="--snapshotter devmapper"
+	fi
+
 	info "Running nerdctl with Kata Containers (${KATA_HYPERVISOR})"
-	sudo nerdctl run --rm --runtime io.containerd.kata-${KATA_HYPERVISOR}.v2 --entrypoint nping instrumentisto/nmap --tcp-connect -c 2 -p 80 www.github.com
+	sudo nerdctl run --rm ${snapshotter_flag} --runtime io.containerd.kata-${KATA_HYPERVISOR}.v2 --entrypoint nping instrumentisto/nmap --tcp-connect -c 2 -p 80 www.github.com
 
 	info "Running nerdctl with Kata Containers (${KATA_HYPERVISOR}) and multiple bridge nwtorks"
-	sudo nerdctl run --rm --net ${net1} --net ${net2} --runtime io.containerd.kata-${KATA_HYPERVISOR}.v2 alpine ip a
+	sudo nerdctl run --rm ${snapshotter_flag} --net ${net1} --net ${net2} --runtime io.containerd.kata-${KATA_HYPERVISOR}.v2 alpine ip a
 
 	info "Running nerdctl with Kata Containers (${KATA_HYPERVISOR}) and ipvlan network"
-	sudo nerdctl run  --rm --net ${ipvlan_net_name}  --runtime io.containerd.kata-${KATA_HYPERVISOR}.v2 alpine ip a | grep "eth0"
+	sudo nerdctl run --rm ${snapshotter_flag} --net ${ipvlan_net_name} --runtime io.containerd.kata-${KATA_HYPERVISOR}.v2 alpine ip a | grep "eth0"
 
 	info "Running nerdctl with Kata Containers (${KATA_HYPERVISOR}) and macvlan network"
-	sudo nerdctl run  --rm --net ${macvlan_net_name}  --runtime io.containerd.kata-${KATA_HYPERVISOR}.v2 alpine ip a | grep "eth0"
+	sudo nerdctl run --rm ${snapshotter_flag} --net ${macvlan_net_name} --runtime io.containerd.kata-${KATA_HYPERVISOR}.v2 alpine ip a | grep "eth0"
 
 	info "Removing networks"
 	sudo nerdctl network rm ${macvlan_net_name} ${ipvlan_net_name}
 }
 
+function install_kata_for_nerdctl() {
+	install_kata
+
+	# Firecracker (fc-rs) uses block devices and requires the devmapper
+	# snapshotter; other hypervisors work fine with the default overlayfs.
+	# Must run AFTER install_kata since install_kata may overwrite the
+	# containerd config via overwrite_containerd_config.
+	if [ "${KATA_HYPERVISOR:-}" = "fc-rs" ]; then
+		configure_devmapper_for_containerd
+	fi
+}
+
 function main() {
 	action="${1:-}"
 	case "${action}" in
 		install-dependencies) install_dependencies ;;
-		install-kata) install_kata ;;
+		install-kata) install_kata_for_nerdctl ;;
 		run) run ;;
 		collect-artifacts) collect_artifacts ;;
 		*) >&2 die "Invalid argument" ;;
diff --git a/tests/stability/gha-run.sh b/tests/stability/gha-run.sh
index 4e9872d54d..87147f210b 100755
--- a/tests/stability/gha-run.sh
+++ b/tests/stability/gha-run.sh
@@ -48,11 +48,21 @@ function run() {
 #	bash "${stability_dir}/agent_stability_test.sh"
 }
 
+function install_kata_for_stability() {
+	install_kata
+
+	# Firecracker (fc-rs) uses block devices and requires the devmapper
+	# snapshotter; other hypervisors work fine with the default overlayfs.
+	if [ "${KATA_HYPERVISOR:-}" = "fc-rs" ]; then
+		configure_devmapper_for_containerd
+	fi
+}
+
 function main() {
 	action="${1:-}"
 	case "${action}" in
 		install-dependencies) install_dependencies ;;
-		install-kata) install_kata ;;
+		install-kata) install_kata_for_stability ;;
 		enabling-hypervisor) enabling_hypervisor ;;
 		run) run ;;
 		*) >&2 die "Invalid argument" ;;