diff --git a/UEFI/README.md b/UEFI/README.md
index be05c44..b82aba6 100644
--- a/UEFI/README.md
+++ b/UEFI/README.md
@@ -117,6 +117,53 @@ I am running Ubuntu 17.04 on Intel i5-6500 + ASUS Z170-AR motherboard + NVIDIA
 * To reuse the keyboard and mouse devices from the host, setup "Automatic
   login" in System Preferences in macOS and configure Synergy software.
 
+### USB passthrough notes
+
+These steps will need to be adapted for your particular setup.
+
+* Isolate the passthrough PCIe devices with vfio-pci, with the help of `lspci
+  -nnk` command.
+
+  ```
+  $ lspci -nn
+  ...
+  01:00.0 ... NVIDIA Corporation [GeForce GTX 1050 Ti] [10de:1c82]
+  01:00.1 Audio device: NVIDIA Corporation Device [10de:0fb9]
+  03:00.0 USB controller: ASMedia ASM1142 USB 3.1 Host Controller [1b21:1242]
+  ```
+
+  Add `1b21:1242` to `/etc/modprobe.d/vfio.conf` file in the required format.
+
+* Update initramfs, and then reboot.
+
+  ```
+  $ sudo update-initramfs -k all -u
+  ```
+
+* Use the helper scripts to isolate the USB controller.
+
+  ```
+  $ scripts/lsgroup.sh
+  ### Group 7 ###
+      00:1c.0 PCI bridge: Intel Corporation Sunrise ...
+  ### Group 15 ###
+      06:00.0 Audio device: Creative Labs Sound Core3D ...
+  ### Group 5 ###
+      00:17.0 SATA controller: Intel Corporation Sunrise ...
+  ### Group 13 ###
+      03:00.0 USB controller: ASMedia ASM1142 USB 3.1 Host Controller
+  ```
+
+  ```
+  $ scripts/vfio-group.sh 13
+  ```
+
+* Add `-device vfio-pci,host=03:00.0,bus=pcie.0 \` line to the
+  `boot-passthrough.sh` script.
+
+* Boot the VM, and devices attached to the ASMedia USB controller should just
+  work under macOS.
+
 ### Synergy Notes
 
 * Get Synergy from https://sourceforge.net/projects/synergy-stable-builds.
diff --git a/scripts/lsgroup.sh b/scripts/lsgroup.sh
new file mode 100755
index 0000000..a3259d5
--- /dev/null
+++ b/scripts/lsgroup.sh
@@ -0,0 +1,15 @@
+#!/bin/sh
+
+# mafferri (https://bbs.archlinux.org)
+
+BASE="/sys/kernel/iommu_groups"
+
+for i in $(find $BASE -maxdepth 1 -mindepth 1 -type d); do
+	GROUP=$(basename $i)
+	echo "### Group $GROUP ###"
+	for j in $(find $i/devices -type l); do
+		DEV=$(basename $j)
+		echo -n "    "
+		lspci -s $DEV
+	done
+done
diff --git a/scripts/vfio-group.sh b/scripts/vfio-group.sh
new file mode 100755
index 0000000..bd1c10e
--- /dev/null
+++ b/scripts/vfio-group.sh
@@ -0,0 +1,32 @@
+#!/bin/sh
+
+# mafferri (https://bbs.archlinux.org)
+
+if [ ! -e /sys/kernel/iommu_groups/$1 ]; then
+	echo "IOMMU group $1 not found"
+	exit 1
+fi
+
+if [ ! -e /sys/bus/pci/drivers/vfio-pci ]; then
+	sudo modprobe vfio-pci
+fi
+
+for i in $(ls /sys/kernel/iommu_groups/$1/devices/); do
+	if [ -e /sys/kernel/iommu_groups/$1/devices/$i/driver ]; then
+		if [ "$(basename $(readlink -f \
+			/sys/kernel/iommu_groups/$1/devices/$i/driver))" != \
+			"pcieport" ]; then
+			echo $i | sudo tee \
+				/sys/kernel/iommu_groups/$1/devices/$i/driver/unbind
+		fi
+	fi
+done
+
+for i in $(ls /sys/kernel/iommu_groups/$1/devices/); do
+	if [ ! -e /sys/kernel/iommu_groups/$1/devices/$i/driver ]; then
+		VEN=$(cat /sys/kernel/iommu_groups/$1/devices/$i/vendor)
+		DEV=$(cat /sys/kernel/iommu_groups/$1/devices/$i/device)
+		echo $VEN $DEV | sudo tee \
+			/sys/bus/pci/drivers/vfio-pci/new_id
+	fi
+done
diff --git a/scripts/vfio-ungroup.sh b/scripts/vfio-ungroup.sh
new file mode 100755
index 0000000..f837aeb
--- /dev/null
+++ b/scripts/vfio-ungroup.sh
@@ -0,0 +1,21 @@
+#!/bin/sh
+
+# mafferri (https://bbs.archlinux.org)
+
+if [ ! -e /sys/kernel/iommu_groups/$1 ]; then
+	echo "IOMMU group $1 not found"
+	exit 1
+fi
+
+for i in $(ls /sys/kernel/iommu_groups/$1/devices/); do
+	VEN=$(cat /sys/kernel/iommu_groups/$1/devices/$i/vendor)
+	DEV=$(cat /sys/kernel/iommu_groups/$1/devices/$i/device)
+	echo $VEN $DEV | sudo tee \
+		/sys/bus/pci/drivers/vfio-pci/remove_id
+	echo $i | sudo tee \
+		/sys/kernel/iommu_groups/$1/devices/$i/driver/unbind
+done
+
+for i in $(ls /sys/kernel/iommu_groups/$1/devices/); do
+	echo $i | sudo tee /sys/bus/pci/drivers_probe
+done