diff --git a/chisel3 b/chisel3
index cae110e0..3e6ef13f 160000
--- a/chisel3
+++ b/chisel3
@@ -1 +1 @@
-Subproject commit cae110e06d7dfb206e6d50565ee25221b8c6d0a5
+Subproject commit 3e6ef13ff5cda2e65efbbf5d306cc101582ad0e5
diff --git a/firrtl b/firrtl
index 8528ba76..7f280a5b 160000
--- a/firrtl
+++ b/firrtl
@@ -1 +1 @@
-Subproject commit 8528ba768003a359bf6c40d2fdc102c4a0d6bea7
+Subproject commit 7f280a5b0821c61284e9bf9ed7780cc825f7f3e8
diff --git a/src/main/scala/diplomacy/Nodes.scala b/src/main/scala/diplomacy/Nodes.scala
index 0796a367..312e9997 100644
--- a/src/main/scala/diplomacy/Nodes.scala
+++ b/src/main/scala/diplomacy/Nodes.scala
@@ -4,6 +4,7 @@ package diplomacy
 
 import Chisel._
 import config._
+import util.HeterogeneousBag
 import scala.collection.mutable.ListBuffer
 import chisel3.internal.sourceinfo.SourceInfo
 
@@ -14,7 +15,7 @@ import chisel3.internal.sourceinfo.SourceInfo
 trait InwardNodeImp[DI, UI, EI, BI <: Data]
 {
   def edgeI(pd: DI, pu: UI): EI
-  def bundleI(ei: Seq[EI]): Vec[BI]
+  def bundleI(ei: EI): BI
   def colour: String
   def connect(bindings: () => Seq[(EI, BI, BI)])(implicit p: Parameters, sourceInfo: SourceInfo): (Option[LazyModule], () => Unit) = {
     (None, () => bindings().foreach { case (_, i, o) => i <> o })
@@ -33,7 +34,7 @@ trait InwardNodeImp[DI, UI, EI, BI <: Data]
 trait OutwardNodeImp[DO, UO, EO, BO <: Data]
 {
   def edgeO(pd: DO, pu: UO): EO
-  def bundleO(eo: Seq[EO]): Vec[BO]
+  def bundleO(eo: EO): BO
 
   // optional methods to track node graph
   def mixO(pd: DO, node: OutwardNode[DO, UO, BO]): DO = pd // insert node into parameters
@@ -112,7 +113,7 @@ trait InwardNode[DI, UI, BI <: Data] extends BaseNode with InwardNodeHandle[DI,
   protected[diplomacy] val iStar: Int
   protected[diplomacy] val iPortMapping: Seq[(Int, Int)]
   protected[diplomacy] val iParams: Seq[UI]
-  val bundleIn: Vec[BI]
+  val bundleIn: HeterogeneousBag[BI]
 }
 
 trait OutwardNodeHandle[DO, UO, BO <: Data]
@@ -145,7 +146,7 @@ trait OutwardNode[DO, UO, BO <: Data] extends BaseNode with OutwardNodeHandle[DO
   protected[diplomacy] val oStar: Int
   protected[diplomacy] val oPortMapping: Seq[(Int, Int)]
   protected[diplomacy] val oParams: Seq[DO]
-  val bundleOut: Vec[BO]
+  val bundleOut: HeterogeneousBag[BO]
 }
 
 abstract class MixedNode[DI, UI, EI, BI <: Data, DO, UO, EO, BO <: Data](
@@ -218,14 +219,14 @@ abstract class MixedNode[DI, UI, EI, BI <: Data, DO, UO, EO, BO <: Data](
   lazy val externalEdgesIn = if (externalIn) {edgesIn} else { Seq() }
 
   val flip = false // needed for blind nodes
-  private def flipO(b: Vec[BO]) = if (flip) b.flip else b
-  private def flipI(b: Vec[BI]) = if (flip) b      else b.flip
+  private def flipO(b: HeterogeneousBag[BO]) = if (flip) b.flip else b
+  private def flipI(b: HeterogeneousBag[BI]) = if (flip) b      else b.flip
   val wire = false // needed if you want to grab access to from inside a module
-  private def wireO(b: Vec[BO]) = if (wire) Wire(b) else b
-  private def wireI(b: Vec[BI]) = if (wire) Wire(b) else b
+  private def wireO(b: HeterogeneousBag[BO]) = if (wire) Wire(b) else b
+  private def wireI(b: HeterogeneousBag[BI]) = if (wire) Wire(b) else b
 
-  lazy val bundleOut = wireO(flipO(outer.bundleO(edgesOut)))
-  lazy val bundleIn  = wireI(flipI(inner.bundleI(edgesIn)))
+  lazy val bundleOut = wireO(flipO(HeterogeneousBag(edgesOut.map(outer.bundleO(_)))))
+  lazy val bundleIn  = wireI(flipI(HeterogeneousBag(edgesIn .map(inner.bundleI(_)))))
 
   // connects the outward part of a node with the inward part of this node
   private def bind(h: OutwardNodeHandle[DI, UI, BI], binding: NodeBinding)(implicit p: Parameters, sourceInfo: SourceInfo): Option[LazyModule] = {
diff --git a/src/main/scala/rocketchip/BaseTop.scala b/src/main/scala/rocketchip/BaseTop.scala
index b5a8c582..7e2638d3 100644
--- a/src/main/scala/rocketchip/BaseTop.scala
+++ b/src/main/scala/rocketchip/BaseTop.scala
@@ -12,6 +12,7 @@ import uncore.devices._
 import util._
 import rocket._
 
+/** BareTop is the root class for creating a top-level RTL module */
 abstract class BareTop(implicit p: Parameters) extends LazyModule {
   ElaborationArtefacts.add("graphml", graphML)
 }
@@ -26,17 +27,20 @@ abstract class BareTopModule[+L <: BareTop, +B <: BareTopBundle[L]](_outer: L, _
   val io = _io ()
 }
 
-/** Base Top with no Periphery */
-trait TopNetwork extends HasPeripheryParameters {
-  val module: TopNetworkModule
+/** HasTopLevelNetworks provides buses that will serve as attachment points,
+  * for use in sub-traits that connect individual agents or external ports.
+  */
+trait HasTopLevelNetworks extends HasPeripheryParameters {
+  val module: HasTopLevelNetworksModule
 
-  // Add a SoC and peripheral bus
-  val socBus = LazyModule(new TLXbar)
-  val peripheryBus = LazyModule(new TLXbar)
-  val intBus = LazyModule(new IntXbar)
-  val l2 = LazyModule(new TLBuffer)
-  val mem = Seq.fill(p(coreplex.BankedL2Config).nMemoryChannels) { LazyModule(new TLXbar) }
+  val socBus = LazyModule(new TLXbar)          // Wide or unordered-access slave devices (TL-UH)
+  val peripheryBus = LazyModule(new TLXbar)    // Narrow and ordered-access slave devices (TL-UL)
+  val intBus = LazyModule(new IntXbar)         // Interrupts
+  val l2FrontendBus = LazyModule(new TLBuffer) // Master devices talking to the frontside of the L2
+  val mem = Seq.fill(nMemoryChannels) { LazyModule(new TLXbar) } // Ports out to DRAM
 
+  // The peripheryBus hangs off of socBus;
+  // here we convert TL-UH -> TL-UL
   peripheryBus.node :=
     TLBuffer()(
     TLWidthWidget(socBusConfig.beatBytes)(
@@ -44,23 +48,23 @@ trait TopNetwork extends HasPeripheryParameters {
     socBus.node)))
 }
 
-trait TopNetworkBundle extends HasPeripheryParameters {
-  val outer: TopNetwork
+trait HasTopLevelNetworksBundle extends HasPeripheryParameters {
+  val outer: HasTopLevelNetworks
 }
 
-trait TopNetworkModule extends HasPeripheryParameters {
-  val io: TopNetworkBundle
-  val outer: TopNetwork
+trait HasTopLevelNetworksModule extends HasPeripheryParameters {
+  val outer: HasTopLevelNetworks
+  val io: HasTopLevelNetworksBundle
 }
 
-/** Base Top with no Periphery */
+/** Base Top class with no peripheral devices or ports added */
 class BaseTop(implicit p: Parameters) extends BareTop
-    with TopNetwork {
+    with HasTopLevelNetworks {
   override lazy val module = new BaseTopModule(this, () => new BaseTopBundle(this))
 }
 
 class BaseTopBundle[+L <: BaseTop](_outer: L) extends BareTopBundle(_outer)
-    with TopNetworkBundle
+    with HasTopLevelNetworksBundle
 
 class BaseTopModule[+L <: BaseTop, +B <: BaseTopBundle[L]](_outer: L, _io: () => B) extends BareTopModule(_outer, _io)
-    with TopNetworkModule
+    with HasTopLevelNetworksModule
diff --git a/src/main/scala/rocketchip/Periphery.scala b/src/main/scala/rocketchip/Periphery.scala
index 0181cf62..d8d4aae5 100644
--- a/src/main/scala/rocketchip/Periphery.scala
+++ b/src/main/scala/rocketchip/Periphery.scala
@@ -37,18 +37,22 @@ case object ZeroConfig extends Field[ZeroConfig]
 /** Utility trait for quick access to some relevant parameters */
 trait HasPeripheryParameters {
   implicit val p: Parameters
-  lazy val peripheryBusConfig = p(PeripheryBusConfig)
-  lazy val socBusConfig = p(SOCBusConfig)
-  lazy val cacheBlockBytes = p(CacheBlockBytes)
-  lazy val peripheryBusArithmetic = p(PeripheryBusArithmetic)
+  def peripheryBusConfig = p(PeripheryBusConfig)
+  def peripheryBusBytes = peripheryBusConfig.beatBytes
+  def socBusConfig = p(SOCBusConfig)
+  def socBusBytes = socBusConfig.beatBytes
+  def cacheBlockBytes = p(CacheBlockBytes)
+  def peripheryBusArithmetic = p(PeripheryBusArithmetic)
+  def nMemoryChannels = p(coreplex.BankedL2Config).nMemoryChannels
 }
 
 /////
 
 trait PeripheryExtInterrupts {
-  this: TopNetwork =>
+  this: HasTopLevelNetworks =>
 
-  val extInterrupts = IntBlindInputNode(p(NExtTopInterrupts))
+  val nExtInterrupts = p(NExtTopInterrupts)
+  val extInterrupts = IntInternalInputNode(nExtInterrupts)
   val extInterruptXing = LazyModule(new IntXing)
 
   intBus.intnode := extInterruptXing.intnode
@@ -56,23 +60,24 @@ trait PeripheryExtInterrupts {
 }
 
 trait PeripheryExtInterruptsBundle {
-  this: TopNetworkBundle {
+  this: HasTopLevelNetworksBundle {
     val outer: PeripheryExtInterrupts
   } =>
-  val interrupts = outer.extInterrupts.bundleIn
+  val interrupts = UInt(INPUT, width = outer.nExtInterrupts)
 }
 
 trait PeripheryExtInterruptsModule {
-  this: TopNetworkModule {
+  this: HasTopLevelNetworksModule {
     val outer: PeripheryExtInterrupts
     val io: PeripheryExtInterruptsBundle
   } =>
+  outer.extInterrupts.bundleIn(0).zipWithIndex.foreach { case(o, i) => o := io.interrupts(i) }
 }
 
 /////
 
 trait PeripheryMasterAXI4Mem {
-  this: TopNetwork =>
+  this: HasTopLevelNetworks =>
   val module: PeripheryMasterAXI4MemModule
 
   private val config = p(ExtMem)
@@ -105,14 +110,14 @@ trait PeripheryMasterAXI4Mem {
 }
 
 trait PeripheryMasterAXI4MemBundle {
-  this: TopNetworkBundle {
+  this: HasTopLevelNetworksBundle {
     val outer: PeripheryMasterAXI4Mem
   } =>
   val mem_axi4 = outer.mem_axi4.bundleOut
 }
 
 trait PeripheryMasterAXI4MemModule {
-  this: TopNetworkModule {
+  this: HasTopLevelNetworksModule {
     val outer: PeripheryMasterAXI4Mem
     val io: PeripheryMasterAXI4MemBundle
   } =>
@@ -121,7 +126,7 @@ trait PeripheryMasterAXI4MemModule {
 /////
 
 trait PeripheryZero {
-  this: TopNetwork =>
+  this: HasTopLevelNetworks =>
   val module: PeripheryZeroModule
 
   private val config = p(ZeroConfig)
@@ -136,13 +141,13 @@ trait PeripheryZero {
 }
 
 trait PeripheryZeroBundle {
-  this: TopNetworkBundle {
+  this: HasTopLevelNetworksBundle {
     val outer: PeripheryZero
   } =>
 }
 
 trait PeripheryZeroModule {
-  this: TopNetworkModule {
+  this: HasTopLevelNetworksModule {
     val outer: PeripheryZero
     val io: PeripheryZeroBundle
   } =>
@@ -152,7 +157,7 @@ trait PeripheryZeroModule {
 
 // PeripheryMasterAXI4MMIO is an example, make your own cake pattern like this one.
 trait PeripheryMasterAXI4MMIO {
-  this: TopNetwork =>
+  this: HasTopLevelNetworks =>
 
   private val config = p(ExtBus)
   val mmio_axi4 = AXI4BlindOutputNode(Seq(AXI4SlavePortParameters(
@@ -173,14 +178,14 @@ trait PeripheryMasterAXI4MMIO {
 }
 
 trait PeripheryMasterAXI4MMIOBundle {
-  this: TopNetworkBundle {
+  this: HasTopLevelNetworksBundle {
     val outer: PeripheryMasterAXI4MMIO
   } =>
   val mmio_axi4 = outer.mmio_axi4.bundleOut
 }
 
 trait PeripheryMasterAXI4MMIOModule {
-  this: TopNetworkModule {
+  this: HasTopLevelNetworksModule {
     val outer: PeripheryMasterAXI4MMIO
     val io: PeripheryMasterAXI4MMIOBundle
   } =>
@@ -190,26 +195,26 @@ trait PeripheryMasterAXI4MMIOModule {
 /////
 
 // PeripherySlaveAXI4 is an example, make your own cake pattern like this one.
-trait PeripherySlaveAXI4 extends TopNetwork {
+trait PeripherySlaveAXI4 extends HasTopLevelNetworks {
   private val config = p(ExtIn)
-  val l2_axi4 = AXI4BlindInputNode(Seq(AXI4MasterPortParameters(
+  val l2FrontendAXI4Node = AXI4BlindInputNode(Seq(AXI4MasterPortParameters(
     masters = Seq(AXI4MasterParameters(
       id = IdRange(0, 1 << config.idBits))))))
 
-  l2.node :=
+  l2FrontendBus.node :=
     TLSourceShrinker(1 << config.sourceBits)(
     TLWidthWidget(config.beatBytes)(
     AXI4ToTL()(
     AXI4Fragmenter()(
-    l2_axi4))))
+    l2FrontendAXI4Node))))
 }
 
-trait PeripherySlaveAXI4Bundle extends TopNetworkBundle {
+trait PeripherySlaveAXI4Bundle extends HasTopLevelNetworksBundle {
   val outer: PeripherySlaveAXI4
-  val l2_axi4 = outer.l2_axi4.bundleIn
+  val l2_frontend_bus_axi4 = outer.l2FrontendAXI4Node.bundleIn
 }
 
-trait PeripherySlaveAXI4Module extends TopNetworkModule {
+trait PeripherySlaveAXI4Module extends HasTopLevelNetworksModule {
   val outer: PeripherySlaveAXI4
   val io: PeripherySlaveAXI4Bundle
   // nothing to do
@@ -219,7 +224,7 @@ trait PeripherySlaveAXI4Module extends TopNetworkModule {
 
 // Add an external TL-UL slave
 trait PeripheryMasterTLMMIO {
-  this: TopNetwork =>
+  this: HasTopLevelNetworks =>
 
   private val config = p(ExtBus)
   val mmio_tl = TLBlindOutputNode(Seq(TLManagerPortParameters(
@@ -239,14 +244,14 @@ trait PeripheryMasterTLMMIO {
 }
 
 trait PeripheryMasterTLMMIOBundle {
-  this: TopNetworkBundle {
+  this: HasTopLevelNetworksBundle {
     val outer: PeripheryMasterTLMMIO
   } =>
   val mmio_tl = outer.mmio_tl.bundleOut
 }
 
 trait PeripheryMasterTLMMIOModule {
-  this: TopNetworkModule {
+  this: HasTopLevelNetworksModule {
     val outer: PeripheryMasterTLMMIO
     val io: PeripheryMasterTLMMIOBundle
   } =>
@@ -256,24 +261,24 @@ trait PeripheryMasterTLMMIOModule {
 /////
 
 // NOTE: this port is NOT allowed to issue Acquires
-trait PeripherySlaveTL extends TopNetwork {
+trait PeripherySlaveTL extends HasTopLevelNetworks {
   private val config = p(ExtIn)
-  val l2_tl = TLBlindInputNode(Seq(TLClientPortParameters(
+  val l2FrontendTLNode = TLBlindInputNode(Seq(TLClientPortParameters(
     clients = Seq(TLClientParameters(
       sourceId = IdRange(0, 1 << config.idBits))))))
 
-  l2.node :=
+  l2FrontendBus.node :=
     TLSourceShrinker(1 << config.sourceBits)(
     TLWidthWidget(config.beatBytes)(
-    l2_tl))
+    l2FrontendTLNode))
 }
 
-trait PeripherySlaveTLBundle extends TopNetworkBundle {
+trait PeripherySlaveTLBundle extends HasTopLevelNetworksBundle {
   val outer: PeripherySlaveTL
-  val l2_tl = outer.l2_tl.bundleIn
+  val l2_frontend_bus_tl = outer.l2FrontendTLNode.bundleIn
 }
 
-trait PeripherySlaveTLModule extends TopNetworkModule {
+trait PeripherySlaveTLModule extends HasTopLevelNetworksModule {
   val outer: PeripherySlaveTL
   val io: PeripherySlaveTLBundle
   // nothing to do
@@ -282,7 +287,7 @@ trait PeripherySlaveTLModule extends TopNetworkModule {
 /////
 
 trait PeripheryBootROM {
-  this: TopNetwork =>
+  this: HasTopLevelNetworks =>
   val coreplex: CoreplexRISCVPlatform
 
   private val bootrom_address = 0x1000
@@ -293,13 +298,13 @@ trait PeripheryBootROM {
 }
 
 trait PeripheryBootROMBundle {
-  this: TopNetworkBundle {
+  this: HasTopLevelNetworksBundle {
     val outer: PeripheryBootROM
   } =>
 }
 
 trait PeripheryBootROMModule {
-  this: TopNetworkModule {
+  this: HasTopLevelNetworksModule {
     val outer: PeripheryBootROM
     val io: PeripheryBootROMBundle
   } =>
@@ -308,20 +313,20 @@ trait PeripheryBootROMModule {
 /////
 
 trait PeripheryTestRAM {
-  this: TopNetwork =>
+  this: HasTopLevelNetworks =>
 
   val testram = LazyModule(new TLRAM(AddressSet(0x52000000, 0xfff), true, peripheryBusConfig.beatBytes))
   testram.node := TLFragmenter(peripheryBusConfig.beatBytes, cacheBlockBytes)(peripheryBus.node)
 }
 
 trait PeripheryTestRAMBundle {
-  this: TopNetworkBundle {
+  this: HasTopLevelNetworksBundle {
     val outer: PeripheryTestRAM
   } =>
 }
 
 trait PeripheryTestRAMModule {
-  this: TopNetworkModule {
+  this: HasTopLevelNetworksModule {
     val outer: PeripheryTestRAM
     val io: PeripheryTestRAMBundle
   } =>
@@ -330,19 +335,19 @@ trait PeripheryTestRAMModule {
 /////
 
 trait PeripheryTestBusMaster {
-  this: TopNetwork =>
+  this: HasTopLevelNetworks =>
   val fuzzer = LazyModule(new TLFuzzer(5000))
   peripheryBus.node := fuzzer.node
 }
 
 trait PeripheryTestBusMasterBundle {
-  this: TopNetworkBundle {
+  this: HasTopLevelNetworksBundle {
     val outer: PeripheryTestBusMaster
   } =>
 }
 
 trait PeripheryTestBusMasterModule {
-  this: TopNetworkModule {
+  this: HasTopLevelNetworksModule {
     val outer: PeripheryTestBusMaster
     val io: PeripheryTestBusMasterBundle
   } =>
diff --git a/src/main/scala/rocketchip/RISCVPlatform.scala b/src/main/scala/rocketchip/RISCVPlatform.scala
index 35aae1fc..7bc9779a 100644
--- a/src/main/scala/rocketchip/RISCVPlatform.scala
+++ b/src/main/scala/rocketchip/RISCVPlatform.scala
@@ -13,18 +13,18 @@ import coreplex._
 
 /// Core with JTAG for debug only
 
-trait PeripheryJTAG extends TopNetwork {
+trait PeripheryJTAG extends HasTopLevelNetworks {
   val module: PeripheryJTAGModule
   val coreplex: CoreplexRISCVPlatform
 }
 
-trait PeripheryJTAGBundle extends TopNetworkBundle {
+trait PeripheryJTAGBundle extends HasTopLevelNetworksBundle {
   val outer: PeripheryJTAG
 
   val jtag = new JTAGIO(true).flip
 }
 
-trait PeripheryJTAGModule extends TopNetworkModule {
+trait PeripheryJTAGModule extends HasTopLevelNetworksModule {
   val outer: PeripheryJTAG
   val io: PeripheryJTAGBundle
 
@@ -38,18 +38,18 @@ trait PeripheryJTAGModule extends TopNetworkModule {
 
 /// Core with DTM for debug only
 
-trait PeripheryDTM extends TopNetwork {
+trait PeripheryDTM extends HasTopLevelNetworks {
   val module: PeripheryDTMModule
   val coreplex: CoreplexRISCVPlatform
 }
 
-trait PeripheryDTMBundle extends TopNetworkBundle {
+trait PeripheryDTMBundle extends HasTopLevelNetworksBundle {
   val outer: PeripheryDTM
 
   val debug = new DebugBusIO().flip
 }
 
-trait PeripheryDTMModule extends TopNetworkModule {
+trait PeripheryDTMModule extends HasTopLevelNetworksModule {
   val outer: PeripheryDTM
   val io: PeripheryDTMBundle
 
@@ -58,19 +58,19 @@ trait PeripheryDTMModule extends TopNetworkModule {
 
 /// Core with DTM or JTAG based on a parameter
 
-trait PeripheryDebug extends TopNetwork {
+trait PeripheryDebug extends HasTopLevelNetworks {
   val module: PeripheryDebugModule
   val coreplex: CoreplexRISCVPlatform
 }
 
-trait PeripheryDebugBundle extends TopNetworkBundle {
+trait PeripheryDebugBundle extends HasTopLevelNetworksBundle {
   val outer: PeripheryDebug
 
   val debug = (!p(IncludeJtagDTM)).option(new DebugBusIO().flip)
   val jtag = (p(IncludeJtagDTM)).option(new JTAGIO(true).flip)
 }
 
-trait PeripheryDebugModule extends TopNetworkModule {
+trait PeripheryDebugModule extends HasTopLevelNetworksModule {
   val outer: PeripheryDebug
   val io: PeripheryDebugBundle
 
@@ -86,16 +86,16 @@ trait PeripheryDebugModule extends TopNetworkModule {
 
 /// Real-time clock is based on RTCPeriod relative to Top clock
 
-trait PeripheryCounter extends TopNetwork {
+trait PeripheryCounter extends HasTopLevelNetworks {
   val module: PeripheryCounterModule
   val coreplex: CoreplexRISCVPlatform
 }
 
-trait PeripheryCounterBundle extends TopNetworkBundle {
+trait PeripheryCounterBundle extends HasTopLevelNetworksBundle {
   val outer: PeripheryCounter
 }
 
-trait PeripheryCounterModule extends TopNetworkModule {
+trait PeripheryCounterModule extends HasTopLevelNetworksModule {
   val outer: PeripheryCounter
   val io: PeripheryCounterBundle
   
@@ -111,16 +111,16 @@ trait PeripheryCounterModule extends TopNetworkModule {
 
 /// Coreplex will power-on running at 0x1000 (BootROM)
 
-trait HardwiredResetVector extends TopNetwork {
+trait HardwiredResetVector extends HasTopLevelNetworks {
   val module: HardwiredResetVectorModule
   val coreplex: CoreplexRISCVPlatform
 }
 
-trait HardwiredResetVectorBundle extends TopNetworkBundle {
+trait HardwiredResetVectorBundle extends HasTopLevelNetworksBundle {
   val outer: HardwiredResetVector
 }
 
-trait HardwiredResetVectorModule extends TopNetworkModule {
+trait HardwiredResetVectorModule extends HasTopLevelNetworksModule {
   val outer: HardwiredResetVector
   val io: HardwiredResetVectorBundle
 
diff --git a/src/main/scala/rocketchip/RocketPlexMaster.scala b/src/main/scala/rocketchip/RocketPlexMaster.scala
index 06591dbb..8d2bf546 100644
--- a/src/main/scala/rocketchip/RocketPlexMaster.scala
+++ b/src/main/scala/rocketchip/RocketPlexMaster.scala
@@ -10,12 +10,12 @@ import uncore.devices._
 import util._
 import coreplex._
 
-trait RocketPlexMaster extends TopNetwork {
+trait RocketPlexMaster extends HasTopLevelNetworks {
   val module: RocketPlexMasterModule
 
   val coreplex = LazyModule(new DefaultCoreplex)
 
-  coreplex.l2in :=* l2.node
+  coreplex.l2in :=* l2FrontendBus.node
   socBus.node := coreplex.mmio
   coreplex.mmioInt := intBus.intnode
 
@@ -23,11 +23,11 @@ trait RocketPlexMaster extends TopNetwork {
   (mem zip coreplex.mem) foreach { case (xbar, channel) => xbar.node :=* channel }
 }
 
-trait RocketPlexMasterBundle extends TopNetworkBundle {
+trait RocketPlexMasterBundle extends HasTopLevelNetworksBundle {
   val outer: RocketPlexMaster
 }
 
-trait RocketPlexMasterModule extends TopNetworkModule {
+trait RocketPlexMasterModule extends HasTopLevelNetworksModule {
   val outer: RocketPlexMaster
   val io: RocketPlexMasterBundle
   val clock: Clock
diff --git a/src/main/scala/rocketchip/TestHarness.scala b/src/main/scala/rocketchip/TestHarness.scala
index f9569534..3d50bed5 100644
--- a/src/main/scala/rocketchip/TestHarness.scala
+++ b/src/main/scala/rocketchip/TestHarness.scala
@@ -15,8 +15,7 @@ class TestHarness()(implicit p: Parameters) extends Module {
   }
   val dut = Module(LazyModule(new ExampleRocketTop).module)
 
-  for (int <- dut.io.interrupts(0))
-    int := Bool(false)
+  dut.io.interrupts := UInt(0)
 
   val channels = p(coreplex.BankedL2Config).nMemoryChannels
   if (channels > 0) Module(LazyModule(new SimAXIMem(channels)).module).io.axi4 <> dut.io.mem_axi4
@@ -30,7 +29,7 @@ class TestHarness()(implicit p: Parameters) extends Module {
   val mmio_sim = Module(LazyModule(new SimAXIMem(1, 4096)).module)
   mmio_sim.io.axi4 <> dut.io.mmio_axi4
 
-  val l2_axi4 = dut.io.l2_axi4(0)
+  val l2_axi4 = dut.io.l2_frontend_bus_axi4(0)
   l2_axi4.ar.valid := Bool(false)
   l2_axi4.aw.valid := Bool(false)
   l2_axi4.w .valid := Bool(false)
diff --git a/src/main/scala/uncore/ahb/Nodes.scala b/src/main/scala/uncore/ahb/Nodes.scala
index 50843943..d50d62f9 100644
--- a/src/main/scala/uncore/ahb/Nodes.scala
+++ b/src/main/scala/uncore/ahb/Nodes.scala
@@ -12,8 +12,8 @@ object AHBImp extends NodeImp[AHBMasterPortParameters, AHBSlavePortParameters, A
   def edgeO(pd: AHBMasterPortParameters, pu: AHBSlavePortParameters): AHBEdgeParameters = AHBEdgeParameters(pd, pu)
   def edgeI(pd: AHBMasterPortParameters, pu: AHBSlavePortParameters): AHBEdgeParameters = AHBEdgeParameters(pd, pu)
 
-  def bundleO(eo: Seq[AHBEdgeParameters]): Vec[AHBBundle] = Vec(eo.size, AHBBundle(AHBBundleParameters.union(eo.map(_.bundle))))
-  def bundleI(ei: Seq[AHBEdgeParameters]): Vec[AHBBundle] = Vec(ei.size, AHBBundle(AHBBundleParameters.union(ei.map(_.bundle))))
+  def bundleO(eo: AHBEdgeParameters): AHBBundle = AHBBundle(eo.bundle)
+  def bundleI(ei: AHBEdgeParameters): AHBBundle = AHBBundle(ei.bundle)
 
   def colour = "#00ccff" // bluish
   override def labelI(ei: AHBEdgeParameters) = (ei.slave.beatBytes * 8).toString
diff --git a/src/main/scala/uncore/ahb/RegisterRouter.scala b/src/main/scala/uncore/ahb/RegisterRouter.scala
index 034df6c8..e514292e 100644
--- a/src/main/scala/uncore/ahb/RegisterRouter.scala
+++ b/src/main/scala/uncore/ahb/RegisterRouter.scala
@@ -80,7 +80,7 @@ abstract class AHBRegisterRouterBase(address: AddressSet, interrupts: Int, concu
   val intnode = uncore.tilelink2.IntSourceNode(interrupts)
 }
 
-case class AHBRegBundleArg(interrupts: Vec[Vec[Bool]], in: Vec[AHBBundle])(implicit val p: Parameters)
+case class AHBRegBundleArg(interrupts: util.HeterogeneousBag[Vec[Bool]], in: util.HeterogeneousBag[AHBBundle])(implicit val p: Parameters)
 
 class AHBRegBundleBase(arg: AHBRegBundleArg) extends Bundle
 {
diff --git a/src/main/scala/uncore/apb/Nodes.scala b/src/main/scala/uncore/apb/Nodes.scala
index 999d23b2..c7d5fa7d 100644
--- a/src/main/scala/uncore/apb/Nodes.scala
+++ b/src/main/scala/uncore/apb/Nodes.scala
@@ -12,8 +12,8 @@ object APBImp extends NodeImp[APBMasterPortParameters, APBSlavePortParameters, A
   def edgeO(pd: APBMasterPortParameters, pu: APBSlavePortParameters): APBEdgeParameters = APBEdgeParameters(pd, pu)
   def edgeI(pd: APBMasterPortParameters, pu: APBSlavePortParameters): APBEdgeParameters = APBEdgeParameters(pd, pu)
 
-  def bundleO(eo: Seq[APBEdgeParameters]): Vec[APBBundle] = Vec(eo.size, APBBundle(APBBundleParameters.union(eo.map(_.bundle))))
-  def bundleI(ei: Seq[APBEdgeParameters]): Vec[APBBundle] = Vec(ei.size, APBBundle(APBBundleParameters.union(ei.map(_.bundle))))
+  def bundleO(eo: APBEdgeParameters): APBBundle = APBBundle(eo.bundle)
+  def bundleI(ei: APBEdgeParameters): APBBundle = APBBundle(ei.bundle)
 
   def colour = "#00ccff" // bluish
   override def labelI(ei: APBEdgeParameters) = (ei.slave.beatBytes * 8).toString
diff --git a/src/main/scala/uncore/apb/RegisterRouter.scala b/src/main/scala/uncore/apb/RegisterRouter.scala
index 2f8bfa86..62585d0e 100644
--- a/src/main/scala/uncore/apb/RegisterRouter.scala
+++ b/src/main/scala/uncore/apb/RegisterRouter.scala
@@ -64,7 +64,7 @@ abstract class APBRegisterRouterBase(address: AddressSet, interrupts: Int, concu
   val intnode = uncore.tilelink2.IntSourceNode(interrupts)
 }
 
-case class APBRegBundleArg(interrupts: Vec[Vec[Bool]], in: Vec[APBBundle])(implicit val p: Parameters)
+case class APBRegBundleArg(interrupts: util.HeterogeneousBag[Vec[Bool]], in: util.HeterogeneousBag[APBBundle])(implicit val p: Parameters)
 
 class APBRegBundleBase(arg: APBRegBundleArg) extends Bundle
 {
diff --git a/src/main/scala/uncore/axi4/Nodes.scala b/src/main/scala/uncore/axi4/Nodes.scala
index fafe4c62..a4e1ca00 100644
--- a/src/main/scala/uncore/axi4/Nodes.scala
+++ b/src/main/scala/uncore/axi4/Nodes.scala
@@ -12,8 +12,8 @@ object AXI4Imp extends NodeImp[AXI4MasterPortParameters, AXI4SlavePortParameters
   def edgeO(pd: AXI4MasterPortParameters, pu: AXI4SlavePortParameters): AXI4EdgeParameters = AXI4EdgeParameters(pd, pu)
   def edgeI(pd: AXI4MasterPortParameters, pu: AXI4SlavePortParameters): AXI4EdgeParameters = AXI4EdgeParameters(pd, pu)
 
-  def bundleO(eo: Seq[AXI4EdgeParameters]): Vec[AXI4Bundle] = Vec(eo.size, AXI4Bundle(AXI4BundleParameters.union(eo.map(_.bundle))))
-  def bundleI(ei: Seq[AXI4EdgeParameters]): Vec[AXI4Bundle] = Vec(ei.size, AXI4Bundle(AXI4BundleParameters.union(ei.map(_.bundle))))
+  def bundleO(eo: AXI4EdgeParameters): AXI4Bundle = AXI4Bundle(eo.bundle)
+  def bundleI(ei: AXI4EdgeParameters): AXI4Bundle = AXI4Bundle(ei.bundle)
 
   def colour = "#00ccff" // bluish
   override def labelI(ei: AXI4EdgeParameters) = (ei.slave.beatBytes * 8).toString
diff --git a/src/main/scala/uncore/axi4/RegisterRouter.scala b/src/main/scala/uncore/axi4/RegisterRouter.scala
index 326f65eb..2da706bf 100644
--- a/src/main/scala/uncore/axi4/RegisterRouter.scala
+++ b/src/main/scala/uncore/axi4/RegisterRouter.scala
@@ -85,7 +85,7 @@ abstract class AXI4RegisterRouterBase(address: AddressSet, interrupts: Int, conc
   val intnode = uncore.tilelink2.IntSourceNode(interrupts)
 }
 
-case class AXI4RegBundleArg(interrupts: Vec[Vec[Bool]], in: Vec[AXI4Bundle])(implicit val p: Parameters)
+case class AXI4RegBundleArg(interrupts: util.HeterogeneousBag[Vec[Bool]], in: util.HeterogeneousBag[AXI4Bundle])(implicit val p: Parameters)
 
 class AXI4RegBundleBase(arg: AXI4RegBundleArg) extends Bundle
 {
diff --git a/src/main/scala/uncore/tilelink2/IntNodes.scala b/src/main/scala/uncore/tilelink2/IntNodes.scala
index ddfa56e1..dab03d4e 100644
--- a/src/main/scala/uncore/tilelink2/IntNodes.scala
+++ b/src/main/scala/uncore/tilelink2/IntNodes.scala
@@ -53,14 +53,8 @@ object IntImp extends NodeImp[IntSourcePortParameters, IntSinkPortParameters, In
 {
   def edgeO(pd: IntSourcePortParameters, pu: IntSinkPortParameters): IntEdge = IntEdge(pd, pu)
   def edgeI(pd: IntSourcePortParameters, pu: IntSinkPortParameters): IntEdge = IntEdge(pd, pu)
-  def bundleO(eo: Seq[IntEdge]): Vec[Vec[Bool]] = {
-    if (eo.isEmpty) Vec(0, Vec(0, Bool())) else
-    Vec(eo.size, Vec(eo.map(_.source.num).max, Bool()))
-  }
-  def bundleI(ei: Seq[IntEdge]): Vec[Vec[Bool]] = {
-    if (ei.isEmpty) Vec(0, Vec(0, Bool())) else
-    Vec(ei.size, Vec(ei.map(_.source.num).max, Bool()))
-  }
+  def bundleO(eo: IntEdge): Vec[Bool] = Vec(eo.source.num, Bool())
+  def bundleI(ei: IntEdge): Vec[Bool] = Vec(ei.source.num, Bool())
 
   def colour = "#0000ff" // blue
   override def labelI(ei: IntEdge) = ei.source.sources.map(_.range.size).sum.toString
@@ -132,6 +126,8 @@ class IntXing()(implicit p: Parameters) extends LazyModule
       val out = intnode.bundleOut
     }
 
-    io.out := RegNext(RegNext(RegNext(io.in)))
+    (io.in zip io.out) foreach { case (in, out) =>
+      out := RegNext(RegNext(RegNext(in)))
+    }
   }
 }
diff --git a/src/main/scala/uncore/tilelink2/Nodes.scala b/src/main/scala/uncore/tilelink2/Nodes.scala
index 22701f12..23b50e01 100644
--- a/src/main/scala/uncore/tilelink2/Nodes.scala
+++ b/src/main/scala/uncore/tilelink2/Nodes.scala
@@ -18,8 +18,8 @@ object TLImp extends NodeImp[TLClientPortParameters, TLManagerPortParameters, TL
   def edgeO(pd: TLClientPortParameters, pu: TLManagerPortParameters): TLEdgeOut = new TLEdgeOut(pd, pu)
   def edgeI(pd: TLClientPortParameters, pu: TLManagerPortParameters): TLEdgeIn  = new TLEdgeIn(pd, pu)
 
-  def bundleO(eo: Seq[TLEdgeOut]): Vec[TLBundle] = Vec(eo.size, TLBundle(TLBundleParameters.union(eo.map(_.bundle))))
-  def bundleI(ei: Seq[TLEdgeIn]):  Vec[TLBundle] = Vec(ei.size, TLBundle(TLBundleParameters.union(ei.map(_.bundle))))
+  def bundleO(eo: TLEdgeOut): TLBundle = TLBundle(eo.bundle)
+  def bundleI(ei: TLEdgeIn):  TLBundle = TLBundle(ei.bundle)
 
   def colour = "#000000" // black
   override def labelI(ei: TLEdgeIn)  = (ei.manager.beatBytes * 8).toString
@@ -156,8 +156,8 @@ object TLAsyncImp extends NodeImp[TLAsyncClientPortParameters, TLAsyncManagerPor
   def edgeO(pd: TLAsyncClientPortParameters, pu: TLAsyncManagerPortParameters): TLAsyncEdgeParameters = TLAsyncEdgeParameters(pd, pu)
   def edgeI(pd: TLAsyncClientPortParameters, pu: TLAsyncManagerPortParameters): TLAsyncEdgeParameters = TLAsyncEdgeParameters(pd, pu)
 
-  def bundleO(eo: Seq[TLAsyncEdgeParameters]): Vec[TLAsyncBundle] = Vec(eo.size, new TLAsyncBundle(TLAsyncBundleParameters.union(eo.map(_.bundle))))
-  def bundleI(ei: Seq[TLAsyncEdgeParameters]): Vec[TLAsyncBundle] = Vec(ei.size, new TLAsyncBundle(TLAsyncBundleParameters.union(ei.map(_.bundle))))
+  def bundleO(eo: TLAsyncEdgeParameters): TLAsyncBundle = new TLAsyncBundle(eo.bundle)
+  def bundleI(ei: TLAsyncEdgeParameters): TLAsyncBundle = new TLAsyncBundle(ei.bundle)
 
   def colour = "#ff0000" // red
   override def labelI(ei: TLAsyncEdgeParameters) = ei.manager.depth.toString
@@ -188,8 +188,8 @@ object TLRationalImp extends NodeImp[TLRationalClientPortParameters, TLRationalM
   def edgeO(pd: TLRationalClientPortParameters, pu: TLRationalManagerPortParameters): TLRationalEdgeParameters = TLRationalEdgeParameters(pd, pu)
   def edgeI(pd: TLRationalClientPortParameters, pu: TLRationalManagerPortParameters): TLRationalEdgeParameters = TLRationalEdgeParameters(pd, pu)
 
-  def bundleO(eo: Seq[TLRationalEdgeParameters]): Vec[TLRationalBundle] = Vec(eo.size, new TLRationalBundle(TLBundleParameters.union(eo.map(_.bundle))))
-  def bundleI(ei: Seq[TLRationalEdgeParameters]): Vec[TLRationalBundle] = Vec(ei.size, new TLRationalBundle(TLBundleParameters.union(ei.map(_.bundle))))
+  def bundleO(eo: TLRationalEdgeParameters): TLRationalBundle = new TLRationalBundle(eo.bundle)
+  def bundleI(ei: TLRationalEdgeParameters): TLRationalBundle = new TLRationalBundle(ei.bundle)
 
   def colour = "#00ff00" // green
 
diff --git a/src/main/scala/uncore/tilelink2/RegisterRouter.scala b/src/main/scala/uncore/tilelink2/RegisterRouter.scala
index 2faa08dc..fc834c6d 100644
--- a/src/main/scala/uncore/tilelink2/RegisterRouter.scala
+++ b/src/main/scala/uncore/tilelink2/RegisterRouter.scala
@@ -86,7 +86,7 @@ abstract class TLRegisterRouterBase(val address: AddressSet, interrupts: Int, co
   val intnode = IntSourceNode(interrupts)
 }
 
-case class TLRegBundleArg(interrupts: Vec[Vec[Bool]], in: Vec[TLBundle])(implicit val p: Parameters)
+case class TLRegBundleArg(interrupts: util.HeterogeneousBag[Vec[Bool]], in: util.HeterogeneousBag[TLBundle])(implicit val p: Parameters)
 
 class TLRegBundleBase(arg: TLRegBundleArg) extends Bundle
 {
diff --git a/src/main/scala/util/Misc.scala b/src/main/scala/util/Misc.scala
index 006aa696..55dc1ed0 100644
--- a/src/main/scala/util/Misc.scala
+++ b/src/main/scala/util/Misc.scala
@@ -160,3 +160,15 @@ object Random
   private def partition(value: UInt, slices: Int) =
     Seq.tabulate(slices)(i => value < UInt(round((i << value.getWidth).toDouble / slices)))
 }
+
+object Majority {
+  def apply(in: Set[Bool]): Bool = {
+    val n = (in.size >> 1) + 1
+    val clauses = in.subsets(n).map(_.reduce(_ && _))
+    clauses.reduce(_ || _)
+  }
+
+  def apply(in: Seq[Bool]): Bool = apply(in.toSet)
+
+  def apply(in: UInt): Bool = apply(in.toBools.toSet)
+}