diff --git a/share/man/man4/virtio.4 b/share/man/man4/virtio.4
--- a/share/man/man4/virtio.4
+++ b/share/man/man4/virtio.4
@@ -53,10 +53,8 @@
 The
 .Nm
 module provides a shared memory transport called a virtqueue.
-The
-.Xr virtio_pci
-device driver represents an emulated PCI device that the hypervisor makes
-available to the VM.
+The virtio_pci device driver represents an emulated PCI device that the
+hypervisor makes available to the VM.
 This device provides the probing, configuration, and
 interrupt notifications needed to interact with the hypervisor.
 .Fx
@@ -92,6 +90,21 @@
 .Xr virtio_scsi 4
 device driver.
 .El
+.Sh LOADER TUNABLES
+Tunables can be set at the
+.Xr loader 8
+prompt before booting the kernel or stored in
+.Xr loader.conf 5 .
+.Bl -tag -width "xxxxxx"
+.It Va hw.virtio.pci.disable_msix
+If set to 1, disables MSI-X.
+The default value is 0.
+.It Va hw.virtio.pci.transitional
+For a transitional VirtIO device, this tunable specifies whether to negotiate
+modern mode and use the modern VirtIO driver (1) or to negotiate legacy mode and
+use the legacy driver (0).
+The default value is 1.
+.El
 .Sh SEE ALSO
 .Xr virtio_balloon 4 ,
 .Xr virtio_blk 4 ,
diff --git a/sys/dev/virtio/pci/virtio_pci.c b/sys/dev/virtio/pci/virtio_pci.c
--- a/sys/dev/virtio/pci/virtio_pci.c
+++ b/sys/dev/virtio/pci/virtio_pci.c
@@ -97,8 +97,13 @@
 MODULE_DEPEND(virtio_pci, pci, 1, 1, 1);
 MODULE_DEPEND(virtio_pci, virtio, 1, 1, 1);
 
+SYSCTL_DECL(_hw_virtio);
+SYSCTL_NODE(_hw_virtio, OID_AUTO, pci, CTLFLAG_RD | CTLFLAG_MPSAFE, 0,
+    "VirtIO PCI driver parameters");
+
 int vtpci_disable_msix = 0;
-TUNABLE_INT("hw.virtio.pci.disable_msix", &vtpci_disable_msix);
+SYSCTL_INT(_hw_virtio_pci, OID_AUTO, disable_msix, CTLFLAG_RDTUN,
+    &vtpci_disable_msix, 0, "If set to 1, disables MSI-X.");
 
 static uint8_t
 vtpci_read_isr(struct vtpci_common *cn)
diff --git a/sys/dev/virtio/pci/virtio_pci_modern.c b/sys/dev/virtio/pci/virtio_pci_modern.c
--- a/sys/dev/virtio/pci/virtio_pci_modern.c
+++ b/sys/dev/virtio/pci/virtio_pci_modern.c
@@ -33,6 +33,7 @@
 #include <sys/bus.h>
 #include <sys/lock.h>
 #include <sys/kernel.h>
+#include <sys/sysctl.h>
 #include <sys/module.h>
 
 #include <machine/bus.h>
@@ -188,8 +189,12 @@
 		    bus_size_t, uint64_t);
 
 /* Tunables. */
+SYSCTL_DECL(_hw_virtio_pci);
+
 static int vtpci_modern_transitional = 0;
-TUNABLE_INT("hw.virtio.pci.transitional", &vtpci_modern_transitional);
+SYSCTL_INT(_hw_virtio_pci, OID_AUTO, transitional, CTLFLAG_RDTUN,
+    &vtpci_modern_transitional, 0,
+    "For a transitional VirtIO device, this tunable specifies whether to negotiate modern mode and use the modern VirtIO driver (1) or to negotiate legacy mode and use the legacy driver (0).");
 
 static device_method_t vtpci_modern_methods[] = {
 	/* Device interface. */
diff --git a/sys/dev/virtio/virtio.c b/sys/dev/virtio/virtio.c
--- a/sys/dev/virtio/virtio.c
+++ b/sys/dev/virtio/virtio.c
@@ -30,6 +30,7 @@
 #include <sys/systm.h>
 #include <sys/kernel.h>
 #include <sys/malloc.h>
+#include <sys/sysctl.h>
 #include <sys/module.h>
 #include <sys/sbuf.h>
 
@@ -90,6 +91,9 @@
 	{ 0, NULL }
 };
 
+SYSCTL_NODE(_hw, OID_AUTO, virtio, CTLFLAG_RD | CTLFLAG_MPSAFE, 0,
+    "VirtIO driver parameters");
+
 const char *
 virtio_device_name(uint16_t devid)
 {