diff --git a/tools/golang/xenlight/gengotypes.py b/tools/golang/xenlight/gengotypes.py
index 1fe56179e2..b68c1aa66b 100644
--- a/tools/golang/xenlight/gengotypes.py
+++ b/tools/golang/xenlight/gengotypes.py
@@ -24,6 +24,10 @@ go_keywords = ['type', 'func']
 go_builtin_types = ['bool', 'string', 'int', 'byte',
                     'uint16', 'uint32', 'uint64']
 
+# cgo preamble for xenlight_helpers.go, created during type generation and
+# written later.
+cgo_helpers_preamble = []
+
 def xenlight_golang_generate_types(path = None, types = None, comment = None):
     """
     Generate a .go file (types.gen.go by default)
@@ -124,7 +128,7 @@ def xenlight_golang_define_struct(ty = None, typename = None, nested = False):
             extras.extend(r[1])
 
         elif isinstance(f.type, idl.KeyedUnion):
-            r = xenlight_golang_define_union(f.type, ty.typename)
+            r = xenlight_golang_define_union(f.type, ty.typename, f.name)
 
             s += r[0]
             extras.extend(r[1])
@@ -137,7 +141,7 @@ def xenlight_golang_define_struct(ty = None, typename = None, nested = False):
 
     return (s,extras)
 
-def xenlight_golang_define_union(ty = None, structname = ''):
+def xenlight_golang_define_union(ty = None, struct_name = '', union_name = ''):
     """
     Generate the Go translation of a KeyedUnion.
 
@@ -149,7 +153,7 @@ def xenlight_golang_define_union(ty = None, structname = ''):
     s = ''
     extras = []
 
-    interface_name = '{}_{}_union'.format(structname, ty.keyvar.name)
+    interface_name = '{}_{}_union'.format(struct_name, ty.keyvar.name)
     interface_name = xenlight_golang_fmt_name(interface_name, exported=False)
 
     s += 'type {} interface {{\n'.format(interface_name)
@@ -163,11 +167,18 @@ def xenlight_golang_define_union(ty = None, structname = ''):
             continue
 
         # Define struct
-        name = '{}_{}_union_{}'.format(structname, ty.keyvar.name, f.name)
+        name = '{}_{}_union_{}'.format(struct_name, ty.keyvar.name, f.name)
         r = xenlight_golang_define_struct(f.type, typename=name)
         extras.append(r[0])
         extras.extend(r[1])
 
+        # This typeof trick ensures that the fields used in the cgo struct
+        # used for marshaling are the same as the fields of the union in the
+        # actual C type, and avoids re-defining all of those fields.
+        s = 'typedef typeof(((struct {} *)NULL)->{}.{}){};'
+        s = s.format(struct_name, union_name, f.name, name)
+        cgo_helpers_preamble.append(s)
+
         # Define function to implement 'union' interface
         name = xenlight_golang_fmt_name(name)
         s = 'func (x {}) is{}(){{}}\n'.format(name, interface_name)
@@ -195,6 +206,7 @@ def xenlight_golang_generate_helpers(path = None, types = None, comment = None):
         if comment is not None:
             f.write(comment)
         f.write('package xenlight\n')
+        f.write('import (\n"unsafe"\n"errors"\n"fmt"\n)\n')
 
         # Cgo preamble
         f.write('/*\n')
@@ -203,15 +215,25 @@ def xenlight_golang_generate_helpers(path = None, types = None, comment = None):
         f.write('#include <libxl.h>\n')
         f.write('\n')
 
+        for s in cgo_helpers_preamble:
+            f.write(s)
+            f.write('\n')
+
         f.write('*/\nimport "C"\n')
 
         for ty in types:
             if not isinstance(ty, idl.Struct):
                 continue
 
-            f.write(xenlight_golang_define_from_C(ty))
+            (fdef, extras) = xenlight_golang_define_from_C(ty)
+
+            f.write(fdef)
             f.write('\n')
 
+            for extra in extras:
+                f.write(extra)
+                f.write('\n')
+
     go_fmt(path)
 
 def xenlight_golang_define_from_C(ty = None):
@@ -225,6 +247,7 @@ def xenlight_golang_define_from_C(ty = None):
     cname  = ty.typename
 
     body = ''
+    extras = []
 
     for f in ty.fields:
         if f.type.typename is not None:
@@ -240,14 +263,17 @@ def xenlight_golang_define_from_C(ty = None):
                 body += xenlight_golang_convert_from_C(nf,outer_name=f.name)
 
         elif isinstance(f.type, idl.KeyedUnion):
-            pass
+            r = xenlight_golang_union_from_C(f.type, f.name, ty.typename)
+
+            body += r[0]
+            extras.extend(r[1])
 
         else:
             raise Exception('type {} not supported'.format(f.type))
 
-    return func.format(goname, cname, body)
+    return (func.format(goname, cname, body), extras)
 
-def xenlight_golang_convert_from_C(ty = None, outer_name = None):
+def xenlight_golang_convert_from_C(ty = None, outer_name = None, cvarname = None):
     """
     Returns a line of Go code that converts the C type represented
     by ty to its corresponding Go type.
@@ -257,6 +283,10 @@ def xenlight_golang_convert_from_C(ty = None, outer_name = None):
     """
     s = ''
 
+    # Use 'xc' as the name for the C variable unless otherwise specified
+    if cvarname is None:
+        cvarname = 'xc'
+
     gotypename = xenlight_golang_fmt_name(ty.type.typename)
     goname     = xenlight_golang_fmt_name(ty.name)
     cname      = ty.name
@@ -280,18 +310,95 @@ def xenlight_golang_convert_from_C(ty = None, outer_name = None):
     if not is_castable:
         # If the type is not castable, we need to call its fromC
         # function.
-        s += 'if err := x.{}.fromC(&xc.{});'.format(goname,cname)
+        s += 'if err := x.{}.fromC(&{}.{});'.format(goname,cvarname,cname)
         s += 'err != nil {\n return err \n}\n'
 
     elif gotypename == 'string':
         # Use the cgo helper for converting C strings.
-        s += 'x.{} = C.GoString(xc.{})\n'.format(goname, cname)
+        s += 'x.{} = C.GoString({}.{})\n'.format(goname,cvarname,cname)
 
     else:
-        s += 'x.{} = {}(xc.{})\n'.format(goname, gotypename, cname)
+        s += 'x.{} = {}({}.{})\n'.format(goname,gotypename,cvarname,cname)
 
     return s
 
+def xenlight_golang_union_from_C(ty = None, union_name = '', struct_name = ''):
+    extras = []
+
+    keyname   = ty.keyvar.name
+    gokeyname = xenlight_golang_fmt_name(keyname)
+    keytype   = ty.keyvar.type.typename
+    gokeytype = xenlight_golang_fmt_name(keytype)
+
+    interface_name = '{}_{}_union'.format(struct_name, keyname)
+    interface_name = xenlight_golang_fmt_name(interface_name, exported=False)
+
+    cgo_keyname = keyname
+    if cgo_keyname in go_keywords:
+        cgo_keyname = '_' + cgo_keyname
+
+    cases = {}
+
+    for f in ty.fields:
+        val = '{}_{}'.format(keytype, f.name)
+        val = xenlight_golang_fmt_name(val)
+
+        # Add to list of cases to make for the switch
+        # statement below.
+        if f.type is None:
+            continue
+
+        cases[f.name] = val
+
+        # Define fromC func for 'union' struct.
+        typename   = '{}_{}_union_{}'.format(struct_name,keyname,f.name)
+        gotypename = xenlight_golang_fmt_name(typename)
+
+        # Define the function here. The cases for keyed unions are a little
+        # different.
+        s = 'func (x *{}) fromC(xc *C.{}) error {{\n'.format(gotypename,struct_name)
+        s += 'if {}(xc.{}) != {} {{\n'.format(gokeytype,cgo_keyname,val)
+        err_string = '"expected union key {}"'.format(val)
+        s += 'return errors.New({})\n'.format(err_string)
+        s += '}\n\n'
+        s += 'tmp := (*C.{})(unsafe.Pointer(&xc.{}[0]))\n'.format(typename,union_name)
+
+        for nf in f.type.fields:
+            s += xenlight_golang_convert_from_C(nf,cvarname='tmp')
+
+        s += 'return nil\n'
+        s += '}\n'
+
+        extras.append(s)
+
+    s = 'x.{} = {}(xc.{})\n'.format(gokeyname,gokeytype,cgo_keyname)
+    s += 'switch x.{}{{\n'.format(gokeyname)
+
+    # Create switch statement to determine which 'union element'
+    # to populate in the Go struct.
+    for case_name, case_val in cases.items():
+        s += 'case {}:\n'.format(case_val)
+
+        gotype = '{}_{}_union_{}'.format(struct_name,keyname,case_name)
+        gotype = xenlight_golang_fmt_name(gotype)
+        goname = '{}_{}'.format(keyname,case_name)
+        goname = xenlight_golang_fmt_name(goname,exported=False)
+
+        s += 'var {} {}\n'.format(goname, gotype)
+        s += 'if err := {}.fromC(xc);'.format(goname)
+        s += 'err != nil {\n return err \n}\n'
+
+        field_name = xenlight_golang_fmt_name('{}_union'.format(keyname))
+        s += 'x.{} = {}\n'.format(field_name, goname)
+
+    # End switch statement
+    s += 'default:\n'
+    err_string = '"invalid union key \'%v\'", x.{}'.format(gokeyname)
+    s += 'return fmt.Errorf({})'.format(err_string)
+    s += '}\n'
+
+    return (s,extras)
+
 def xenlight_golang_fmt_name(name, exported = True):
     """
     Take a given type name and return an
diff --git a/tools/golang/xenlight/helpers.gen.go b/tools/golang/xenlight/helpers.gen.go
index 576aebcf6d..e6eee234c0 100644
--- a/tools/golang/xenlight/helpers.gen.go
+++ b/tools/golang/xenlight/helpers.gen.go
@@ -5,11 +5,28 @@
 //
 package xenlight
 
+import (
+	"errors"
+	"fmt"
+	"unsafe"
+)
+
 /*
 #cgo LDFLAGS: -lxenlight
 #include <stdlib.h>
 #include <libxl.h>
 
+typedef typeof(((struct libxl_channelinfo *)NULL)->u.pty)libxl_channelinfo_connection_union_pty;
+typedef typeof(((struct libxl_domain_build_info *)NULL)->u.hvm)libxl_domain_build_info_type_union_hvm;
+typedef typeof(((struct libxl_domain_build_info *)NULL)->u.pv)libxl_domain_build_info_type_union_pv;
+typedef typeof(((struct libxl_domain_build_info *)NULL)->u.pvh)libxl_domain_build_info_type_union_pvh;
+typedef typeof(((struct libxl_device_usbdev *)NULL)->u.hostdev)libxl_device_usbdev_type_union_hostdev;
+typedef typeof(((struct libxl_device_channel *)NULL)->u.socket)libxl_device_channel_connection_union_socket;
+typedef typeof(((struct libxl_event *)NULL)->u.domain_shutdown)libxl_event_type_union_domain_shutdown;
+typedef typeof(((struct libxl_event *)NULL)->u.disk_eject)libxl_event_type_union_disk_eject;
+typedef typeof(((struct libxl_event *)NULL)->u.operation_complete)libxl_event_type_union_operation_complete;
+typedef typeof(((struct libxl_psr_hw_info *)NULL)->u.cat)libxl_psr_hw_info_type_union_cat;
+typedef typeof(((struct libxl_psr_hw_info *)NULL)->u.mba)libxl_psr_hw_info_type_union_mba;
 */
 import "C"
 
@@ -137,7 +154,28 @@ func (x *Channelinfo) fromC(xc *C.libxl_channelinfo) error {
 	x.State = int(xc.state)
 	x.Evtch = int(xc.evtch)
 	x.Rref = int(xc.rref)
+	x.Connection = ChannelConnection(xc.connection)
+	switch x.Connection {
+	case ChannelConnectionPty:
+		var connectionPty ChannelinfoConnectionUnionPty
+		if err := connectionPty.fromC(xc); err != nil {
+			return err
+		}
+		x.ConnectionUnion = connectionPty
+	default:
+		return fmt.Errorf("invalid union key '%v'", x.Connection)
+	}
+
+	return nil
+}
+
+func (x *ChannelinfoConnectionUnionPty) fromC(xc *C.libxl_channelinfo) error {
+	if ChannelConnection(xc.connection) != ChannelConnectionPty {
+		return errors.New("expected union key ChannelConnectionPty")
+	}
 
+	tmp := (*C.libxl_channelinfo_connection_union_pty)(unsafe.Pointer(&xc.u[0]))
+	x.Path = C.GoString(tmp.path)
 	return nil
 }
 
@@ -340,6 +378,29 @@ func (x *DomainBuildInfo) fromC(xc *C.libxl_domain_build_info) error {
 		return err
 	}
 	x.Tee = TeeType(xc.tee)
+	x.Type = DomainType(xc._type)
+	switch x.Type {
+	case DomainTypePv:
+		var typePv DomainBuildInfoTypeUnionPv
+		if err := typePv.fromC(xc); err != nil {
+			return err
+		}
+		x.TypeUnion = typePv
+	case DomainTypeHvm:
+		var typeHvm DomainBuildInfoTypeUnionHvm
+		if err := typeHvm.fromC(xc); err != nil {
+			return err
+		}
+		x.TypeUnion = typeHvm
+	case DomainTypePvh:
+		var typePvh DomainBuildInfoTypeUnionPvh
+		if err := typePvh.fromC(xc); err != nil {
+			return err
+		}
+		x.TypeUnion = typePvh
+	default:
+		return fmt.Errorf("invalid union key '%v'", x.Type)
+	}
 	x.ArchArm.GicVersion = GicVersion(xc.arch_arm.gic_version)
 	x.ArchArm.Vuart = VuartType(xc.arch_arm.vuart)
 	x.Altp2M = Altp2MMode(xc.altp2m)
@@ -347,6 +408,151 @@ func (x *DomainBuildInfo) fromC(xc *C.libxl_domain_build_info) error {
 	return nil
 }
 
+func (x *DomainBuildInfoTypeUnionHvm) fromC(xc *C.libxl_domain_build_info) error {
+	if DomainType(xc._type) != DomainTypeHvm {
+		return errors.New("expected union key DomainTypeHvm")
+	}
+
+	tmp := (*C.libxl_domain_build_info_type_union_hvm)(unsafe.Pointer(&xc.u[0]))
+	x.Firmware = C.GoString(tmp.firmware)
+	x.Bios = BiosType(tmp.bios)
+	if err := x.Pae.fromC(&tmp.pae); err != nil {
+		return err
+	}
+	if err := x.Apic.fromC(&tmp.apic); err != nil {
+		return err
+	}
+	if err := x.Acpi.fromC(&tmp.acpi); err != nil {
+		return err
+	}
+	if err := x.AcpiS3.fromC(&tmp.acpi_s3); err != nil {
+		return err
+	}
+	if err := x.AcpiS4.fromC(&tmp.acpi_s4); err != nil {
+		return err
+	}
+	if err := x.AcpiLaptopSlate.fromC(&tmp.acpi_laptop_slate); err != nil {
+		return err
+	}
+	if err := x.Nx.fromC(&tmp.nx); err != nil {
+		return err
+	}
+	if err := x.Viridian.fromC(&tmp.viridian); err != nil {
+		return err
+	}
+	if err := x.ViridianEnable.fromC(&tmp.viridian_enable); err != nil {
+		return err
+	}
+	if err := x.ViridianDisable.fromC(&tmp.viridian_disable); err != nil {
+		return err
+	}
+	x.Timeoffset = C.GoString(tmp.timeoffset)
+	if err := x.Hpet.fromC(&tmp.hpet); err != nil {
+		return err
+	}
+	if err := x.VptAlign.fromC(&tmp.vpt_align); err != nil {
+		return err
+	}
+	x.MmioHoleMemkb = uint64(tmp.mmio_hole_memkb)
+	x.TimerMode = TimerMode(tmp.timer_mode)
+	if err := x.NestedHvm.fromC(&tmp.nested_hvm); err != nil {
+		return err
+	}
+	if err := x.Altp2M.fromC(&tmp.altp2m); err != nil {
+		return err
+	}
+	x.SystemFirmware = C.GoString(tmp.system_firmware)
+	x.SmbiosFirmware = C.GoString(tmp.smbios_firmware)
+	x.AcpiFirmware = C.GoString(tmp.acpi_firmware)
+	x.Hdtype = Hdtype(tmp.hdtype)
+	if err := x.Nographic.fromC(&tmp.nographic); err != nil {
+		return err
+	}
+	if err := x.Vga.fromC(&tmp.vga); err != nil {
+		return err
+	}
+	if err := x.Vnc.fromC(&tmp.vnc); err != nil {
+		return err
+	}
+	x.Keymap = C.GoString(tmp.keymap)
+	if err := x.Sdl.fromC(&tmp.sdl); err != nil {
+		return err
+	}
+	if err := x.Spice.fromC(&tmp.spice); err != nil {
+		return err
+	}
+	if err := x.GfxPassthru.fromC(&tmp.gfx_passthru); err != nil {
+		return err
+	}
+	x.GfxPassthruKind = GfxPassthruKind(tmp.gfx_passthru_kind)
+	x.Serial = C.GoString(tmp.serial)
+	x.Boot = C.GoString(tmp.boot)
+	if err := x.Usb.fromC(&tmp.usb); err != nil {
+		return err
+	}
+	x.Usbversion = int(tmp.usbversion)
+	x.Usbdevice = C.GoString(tmp.usbdevice)
+	if err := x.VkbDevice.fromC(&tmp.vkb_device); err != nil {
+		return err
+	}
+	x.Soundhw = C.GoString(tmp.soundhw)
+	if err := x.XenPlatformPci.fromC(&tmp.xen_platform_pci); err != nil {
+		return err
+	}
+	if err := x.UsbdeviceList.fromC(&tmp.usbdevice_list); err != nil {
+		return err
+	}
+	x.VendorDevice = VendorDevice(tmp.vendor_device)
+	if err := x.MsVmGenid.fromC(&tmp.ms_vm_genid); err != nil {
+		return err
+	}
+	if err := x.SerialList.fromC(&tmp.serial_list); err != nil {
+		return err
+	}
+	if err := x.Rdm.fromC(&tmp.rdm); err != nil {
+		return err
+	}
+	x.RdmMemBoundaryMemkb = uint64(tmp.rdm_mem_boundary_memkb)
+	x.McaCaps = uint64(tmp.mca_caps)
+	return nil
+}
+
+func (x *DomainBuildInfoTypeUnionPv) fromC(xc *C.libxl_domain_build_info) error {
+	if DomainType(xc._type) != DomainTypePv {
+		return errors.New("expected union key DomainTypePv")
+	}
+
+	tmp := (*C.libxl_domain_build_info_type_union_pv)(unsafe.Pointer(&xc.u[0]))
+	x.Kernel = C.GoString(tmp.kernel)
+	x.SlackMemkb = uint64(tmp.slack_memkb)
+	x.Bootloader = C.GoString(tmp.bootloader)
+	if err := x.BootloaderArgs.fromC(&tmp.bootloader_args); err != nil {
+		return err
+	}
+	x.Cmdline = C.GoString(tmp.cmdline)
+	x.Ramdisk = C.GoString(tmp.ramdisk)
+	x.Features = C.GoString(tmp.features)
+	if err := x.E820Host.fromC(&tmp.e820_host); err != nil {
+		return err
+	}
+	return nil
+}
+
+func (x *DomainBuildInfoTypeUnionPvh) fromC(xc *C.libxl_domain_build_info) error {
+	if DomainType(xc._type) != DomainTypePvh {
+		return errors.New("expected union key DomainTypePvh")
+	}
+
+	tmp := (*C.libxl_domain_build_info_type_union_pvh)(unsafe.Pointer(&xc.u[0]))
+	if err := x.Pvshim.fromC(&tmp.pvshim); err != nil {
+		return err
+	}
+	x.PvshimPath = C.GoString(tmp.pvshim_path)
+	x.PvshimCmdline = C.GoString(tmp.pvshim_cmdline)
+	x.PvshimExtra = C.GoString(tmp.pvshim_extra)
+	return nil
+}
+
 func (x *DeviceVfb) fromC(xc *C.libxl_device_vfb) error {
 	x.BackendDomid = Domid(xc.backend_domid)
 	x.BackendDomname = C.GoString(xc.backend_domname)
@@ -520,10 +726,32 @@ func (x *DeviceUsbctrl) fromC(xc *C.libxl_device_usbctrl) error {
 func (x *DeviceUsbdev) fromC(xc *C.libxl_device_usbdev) error {
 	x.Ctrl = Devid(xc.ctrl)
 	x.Port = int(xc.port)
+	x.Type = UsbdevType(xc._type)
+	switch x.Type {
+	case UsbdevTypeHostdev:
+		var typeHostdev DeviceUsbdevTypeUnionHostdev
+		if err := typeHostdev.fromC(xc); err != nil {
+			return err
+		}
+		x.TypeUnion = typeHostdev
+	default:
+		return fmt.Errorf("invalid union key '%v'", x.Type)
+	}
 
 	return nil
 }
 
+func (x *DeviceUsbdevTypeUnionHostdev) fromC(xc *C.libxl_device_usbdev) error {
+	if UsbdevType(xc._type) != UsbdevTypeHostdev {
+		return errors.New("expected union key UsbdevTypeHostdev")
+	}
+
+	tmp := (*C.libxl_device_usbdev_type_union_hostdev)(unsafe.Pointer(&xc.u[0]))
+	x.Hostbus = byte(tmp.hostbus)
+	x.Hostaddr = byte(tmp.hostaddr)
+	return nil
+}
+
 func (x *DeviceDtdev) fromC(xc *C.libxl_device_dtdev) error {
 	x.Path = C.GoString(xc.path)
 
@@ -565,7 +793,28 @@ func (x *DeviceChannel) fromC(xc *C.libxl_device_channel) error {
 	x.BackendDomname = C.GoString(xc.backend_domname)
 	x.Devid = Devid(xc.devid)
 	x.Name = C.GoString(xc.name)
+	x.Connection = ChannelConnection(xc.connection)
+	switch x.Connection {
+	case ChannelConnectionSocket:
+		var connectionSocket DeviceChannelConnectionUnionSocket
+		if err := connectionSocket.fromC(xc); err != nil {
+			return err
+		}
+		x.ConnectionUnion = connectionSocket
+	default:
+		return fmt.Errorf("invalid union key '%v'", x.Connection)
+	}
+
+	return nil
+}
 
+func (x *DeviceChannelConnectionUnionSocket) fromC(xc *C.libxl_device_channel) error {
+	if ChannelConnection(xc.connection) != ChannelConnectionSocket {
+		return errors.New("expected union key ChannelConnectionSocket")
+	}
+
+	tmp := (*C.libxl_device_channel_connection_union_socket)(unsafe.Pointer(&xc.u[0]))
+	x.Path = C.GoString(tmp.path)
 	return nil
 }
 
@@ -881,7 +1130,63 @@ func (x *Event) fromC(xc *C.libxl_event) error {
 		return err
 	}
 	x.ForUser = uint64(xc.for_user)
+	x.Type = EventType(xc._type)
+	switch x.Type {
+	case EventTypeOperationComplete:
+		var typeOperationComplete EventTypeUnionOperationComplete
+		if err := typeOperationComplete.fromC(xc); err != nil {
+			return err
+		}
+		x.TypeUnion = typeOperationComplete
+	case EventTypeDomainShutdown:
+		var typeDomainShutdown EventTypeUnionDomainShutdown
+		if err := typeDomainShutdown.fromC(xc); err != nil {
+			return err
+		}
+		x.TypeUnion = typeDomainShutdown
+	case EventTypeDiskEject:
+		var typeDiskEject EventTypeUnionDiskEject
+		if err := typeDiskEject.fromC(xc); err != nil {
+			return err
+		}
+		x.TypeUnion = typeDiskEject
+	default:
+		return fmt.Errorf("invalid union key '%v'", x.Type)
+	}
+
+	return nil
+}
+
+func (x *EventTypeUnionDomainShutdown) fromC(xc *C.libxl_event) error {
+	if EventType(xc._type) != EventTypeDomainShutdown {
+		return errors.New("expected union key EventTypeDomainShutdown")
+	}
 
+	tmp := (*C.libxl_event_type_union_domain_shutdown)(unsafe.Pointer(&xc.u[0]))
+	x.ShutdownReason = byte(tmp.shutdown_reason)
+	return nil
+}
+
+func (x *EventTypeUnionDiskEject) fromC(xc *C.libxl_event) error {
+	if EventType(xc._type) != EventTypeDiskEject {
+		return errors.New("expected union key EventTypeDiskEject")
+	}
+
+	tmp := (*C.libxl_event_type_union_disk_eject)(unsafe.Pointer(&xc.u[0]))
+	x.Vdev = C.GoString(tmp.vdev)
+	if err := x.Disk.fromC(&tmp.disk); err != nil {
+		return err
+	}
+	return nil
+}
+
+func (x *EventTypeUnionOperationComplete) fromC(xc *C.libxl_event) error {
+	if EventType(xc._type) != EventTypeOperationComplete {
+		return errors.New("expected union key EventTypeOperationComplete")
+	}
+
+	tmp := (*C.libxl_event_type_union_operation_complete)(unsafe.Pointer(&xc.u[0]))
+	x.Rc = int(tmp.rc)
 	return nil
 }
 
@@ -896,6 +1201,47 @@ func (x *PsrCatInfo) fromC(xc *C.libxl_psr_cat_info) error {
 
 func (x *PsrHwInfo) fromC(xc *C.libxl_psr_hw_info) error {
 	x.Id = uint32(xc.id)
+	x.Type = PsrFeatType(xc._type)
+	switch x.Type {
+	case PsrFeatTypeMba:
+		var typeMba PsrHwInfoTypeUnionMba
+		if err := typeMba.fromC(xc); err != nil {
+			return err
+		}
+		x.TypeUnion = typeMba
+	case PsrFeatTypeCat:
+		var typeCat PsrHwInfoTypeUnionCat
+		if err := typeCat.fromC(xc); err != nil {
+			return err
+		}
+		x.TypeUnion = typeCat
+	default:
+		return fmt.Errorf("invalid union key '%v'", x.Type)
+	}
+
+	return nil
+}
+
+func (x *PsrHwInfoTypeUnionCat) fromC(xc *C.libxl_psr_hw_info) error {
+	if PsrFeatType(xc._type) != PsrFeatTypeCat {
+		return errors.New("expected union key PsrFeatTypeCat")
+	}
+
+	tmp := (*C.libxl_psr_hw_info_type_union_cat)(unsafe.Pointer(&xc.u[0]))
+	x.CosMax = uint32(tmp.cos_max)
+	x.CbmLen = uint32(tmp.cbm_len)
+	x.CdpEnabled = bool(tmp.cdp_enabled)
+	return nil
+}
+
+func (x *PsrHwInfoTypeUnionMba) fromC(xc *C.libxl_psr_hw_info) error {
+	if PsrFeatType(xc._type) != PsrFeatTypeMba {
+		return errors.New("expected union key PsrFeatTypeMba")
+	}
 
+	tmp := (*C.libxl_psr_hw_info_type_union_mba)(unsafe.Pointer(&xc.u[0]))
+	x.CosMax = uint32(tmp.cos_max)
+	x.ThrtlMax = uint32(tmp.thrtl_max)
+	x.Linear = bool(tmp.linear)
 	return nil
 }
