X-Git-Url: https://git.libre-soc.org/?a=blobdiff_plain;f=src%2Fsoc%2Fexperiment%2Fdcache.py;h=e1f82b77dc337467c1f9eeff306adc2ade4a7120;hb=41d2c31f6f0d184a57f468d5b157d6e8c0a44af1;hp=f137a6d815892cca464e9ccdbdeb7ed392fdfca7;hpb=934012494dbe2494fe6e96ba35454cb2d2bd495f;p=soc.git

diff --git a/src/soc/experiment/dcache.py b/src/soc/experiment/dcache.py
index f137a6d8..e1f82b77 100644
--- a/src/soc/experiment/dcache.py
+++ b/src/soc/experiment/dcache.py
@@ -7,12 +7,13 @@ based on Anton Blanchard microwatt dcache.vhdl
 from enum import Enum, unique
 
 from nmigen import Module, Signal, Elaboratable, Cat, Repl, Array, Const
+from nmutil.util import Display
+
+from random import randint
+
 from nmigen.cli import main
 from nmutil.iocontrol import RecordObject
 from nmigen.utils import log2_int
-from nmigen.cli import rtlil
-
-
 from soc.experiment.mem_types import (LoadStore1ToDCacheType,
                                      DCacheToLoadStore1Type,
                                      MMUToDCacheType,
@@ -25,15 +26,27 @@ from soc.experiment.wb_types import (WB_ADDR_BITS, WB_DATA_BITS, WB_SEL_BITS,
                                 WBIOMasterOut, WBIOSlaveOut)
 
 from soc.experiment.cache_ram import CacheRam
-from soc.experiment.plru import PLRU
+#from soc.experiment.plru import PLRU
+from nmutil.plru import PLRU
+
+# for test
+from nmigen_soc.wishbone.sram import SRAM
+from nmigen import Memory
+from nmigen.cli import rtlil
+
+# NOTE: to use cxxsim, export NMIGEN_SIM_MODE=cxxsim from the shell
+# Also, check out the cxxsim nmigen branch, and latest yosys from git
+from nmutil.sim_tmp_alternative import Simulator
+
+from nmutil.util import wrap
 
 
 # TODO: make these parameters of DCache at some point
 LINE_SIZE = 64    # Line size in bytes
-NUM_LINES = 32    # Number of lines in a set
+NUM_LINES = 16    # Number of lines in a set
 NUM_WAYS = 4      # Number of ways
 TLB_SET_SIZE = 64 # L1 DTLB entries per set
-TLB_NUM_WAYS = 2  # L1 DTLB number of sets
+TLB_NUM_WAYS = 4  # L1 DTLB number of sets
 TLB_LG_PGSZ = 12  # L1 DTLB log_2(page_size)
 LOG_LENGTH = 0    # Non-zero to enable log data collection
 
@@ -54,6 +67,10 @@ ROW_PER_LINE = LINE_SIZE // ROW_SIZE
 # to represent the full dcache
 BRAM_ROWS = NUM_LINES * ROW_PER_LINE
 
+print ("ROW_SIZE", ROW_SIZE)
+print ("ROW_PER_LINE", ROW_PER_LINE)
+print ("BRAM_ROWS", BRAM_ROWS)
+print ("NUM_WAYS", NUM_WAYS)
 
 # Bit fields counts in the address
 
@@ -94,26 +111,39 @@ TAG_WIDTH = TAG_BITS + 7 - ((TAG_BITS + 7) % 8)
 WAY_BITS = log2_int(NUM_WAYS)
 
 # Example of layout for 32 lines of 64 bytes:
-#
-# ..  tag    |index|  line  |
-# ..         |   row   |    |
-# ..         |     |---|    | ROW_LINE_BITS  (3)
-# ..         |     |--- - --| LINE_OFF_BITS (6)
-# ..         |         |- --| ROW_OFF_BITS  (3)
-# ..         |----- ---|    | ROW_BITS      (8)
-# ..         |-----|        | INDEX_BITS    (5)
-# .. --------|              | TAG_BITS      (45)
+layout = """\
+  ..  tag    |index|  line  |
+  ..         |   row   |    |
+  ..         |     |---|    | ROW_LINE_BITS  (3)
+  ..         |     |--- - --| LINE_OFF_BITS (6)
+  ..         |         |- --| ROW_OFF_BITS  (3)
+  ..         |----- ---|    | ROW_BITS      (8)
+  ..         |-----|        | INDEX_BITS    (5)
+  .. --------|              | TAG_BITS      (45)
+"""
+print (layout)
+print ("Dcache TAG %d IDX %d ROW_BITS %d ROFF %d LOFF %d RLB %d" % \
+            (TAG_BITS, INDEX_BITS, ROW_BITS,
+             ROW_OFF_BITS, LINE_OFF_BITS, ROW_LINE_BITS))
+print ("index @: %d-%d" % (LINE_OFF_BITS, SET_SIZE_BITS))
+print ("row @: %d-%d" % (LINE_OFF_BITS, ROW_OFF_BITS))
+print ("tag @: %d-%d width %d" % (SET_SIZE_BITS, REAL_ADDR_BITS, TAG_WIDTH))
 
 TAG_RAM_WIDTH = TAG_WIDTH * NUM_WAYS
 
+print ("TAG_RAM_WIDTH", TAG_RAM_WIDTH)
+
 def CacheTagArray():
-    return Array(Signal(TAG_RAM_WIDTH) for x in range(NUM_LINES))
+    return Array(Signal(TAG_RAM_WIDTH, name="cachetag_%d" % x) \
+                        for x in range(NUM_LINES))
 
 def CacheValidBitsArray():
-    return Array(Signal(INDEX_BITS) for x in range(NUM_LINES))
+    return Array(Signal(NUM_WAYS, name="cachevalid_%d" % x) \
+                        for x in range(NUM_LINES))
 
 def RowPerLineValidArray():
-    return Array(Signal() for x in range(ROW_PER_LINE))
+    return Array(Signal(name="rows_valid%d" % x) \
+                        for x in range(ROW_PER_LINE))
 
 # L1 TLB
 TLB_SET_BITS     = log2_int(TLB_SET_SIZE)
@@ -123,10 +153,13 @@ TLB_TAG_WAY_BITS = TLB_NUM_WAYS * TLB_EA_TAG_BITS
 TLB_PTE_BITS     = 64
 TLB_PTE_WAY_BITS = TLB_NUM_WAYS * TLB_PTE_BITS;
 
+def ispow2(x):
+    return (1<<log2_int(x, False)) == x
+
 assert (LINE_SIZE % ROW_SIZE) == 0, "LINE_SIZE not multiple of ROW_SIZE"
-assert (LINE_SIZE % 2) == 0, "LINE_SIZE not power of 2"
-assert (NUM_LINES % 2) == 0, "NUM_LINES not power of 2"
-assert (ROW_PER_LINE % 2) == 0, "ROW_PER_LINE not power of 2"
+assert ispow2(LINE_SIZE), "LINE_SIZE not power of 2"
+assert ispow2(NUM_LINES), "NUM_LINES not power of 2"
+assert ispow2(ROW_PER_LINE), "ROW_PER_LINE not power of 2"
 assert ROW_BITS == (INDEX_BITS + ROW_LINE_BITS), "geometry bits don't add up"
 assert (LINE_OFF_BITS == ROW_OFF_BITS + ROW_LINE_BITS), \
         "geometry bits don't add up"
@@ -139,28 +172,39 @@ assert SET_SIZE_BITS <= TLB_LG_PGSZ, "Set indexed by virtual address"
 
 
 def TLBValidBitsArray():
-    return Array(Signal(TLB_NUM_WAYS) for x in range(TLB_SET_SIZE))
+    return Array(Signal(TLB_NUM_WAYS, name="tlbvalid%d" % x) \
+                for x in range(TLB_SET_SIZE))
+
+def TLBTagEAArray():
+    return Array(Signal(TLB_EA_TAG_BITS, name="tlbtagea%d" % x) \
+                for x in range (TLB_NUM_WAYS))
 
 def TLBTagsArray():
-    return Array(Signal(TLB_TAG_WAY_BITS) for x in range (TLB_SET_SIZE))
+    return Array(Signal(TLB_TAG_WAY_BITS, name="tlbtags%d" % x) \
+                for x in range (TLB_SET_SIZE))
 
 def TLBPtesArray():
-    return Array(Signal(TLB_PTE_WAY_BITS) for x in range(TLB_SET_SIZE))
+    return Array(Signal(TLB_PTE_WAY_BITS, name="tlbptes%d" % x) \
+                for x in range(TLB_SET_SIZE))
 
 def HitWaySet():
-    return Array(Signal(NUM_WAYS) for x in range(TLB_NUM_WAYS))
+    return Array(Signal(WAY_BITS, name="hitway_%d" % x) \
+                        for x in range(TLB_NUM_WAYS))
 
 # Cache RAM interface
 def CacheRamOut():
-    return Array(Signal(WB_DATA_BITS) for x in range(NUM_WAYS))
+    return Array(Signal(WB_DATA_BITS, name="cache_out%d" % x) \
+                 for x in range(NUM_WAYS))
 
 # PLRU output interface
 def PLRUOut():
-    return Array(Signal(WAY_BITS) for x in range(NUM_LINES))
+    return Array(Signal(WAY_BITS, name="plru_out%d" % x) \
+                for x in range(NUM_LINES))
 
 # TLB PLRU output interface
 def TLBPLRUOut():
-    return Array(Signal(TLB_WAY_BITS) for x in range(TLB_SET_SIZE))
+    return Array(Signal(TLB_WAY_BITS, name="tlbplru_out%d" % x) \
+                for x in range(TLB_SET_SIZE))
 
 # Helper functions to decode incoming requests
 #
@@ -174,7 +218,7 @@ def get_row(addr):
 
 # Return the index of a row within a line
 def get_row_of_line(row):
-    return row[:ROW_LINE_BITS]
+    return row[:ROW_BITS][:ROW_LINE_BITS]
 
 # Returns whether this is the last row of a line
 def is_last_row_addr(addr, last):
@@ -198,7 +242,7 @@ def get_tag(addr):
 
 # Read a tag from a tag memory row
 def read_tag(way, tagset):
-    return tagset[way *TAG_WIDTH:way * TAG_WIDTH + TAG_BITS]
+    return tagset.word_select(way, TAG_WIDTH)[:TAG_BITS]
 
 # Read a TLB tag from a TLB tag memory row
 def read_tlb_tag(way, tags):
@@ -212,14 +256,14 @@ def write_tlb_tag(way, tags, tag):
 def read_tlb_pte(way, ptes):
     return ptes.word_select(way, TLB_PTE_BITS)
 
-def write_tlb_pte(way, ptes,newpte):
+def write_tlb_pte(way, ptes, newpte):
     return read_tlb_pte(way, ptes).eq(newpte)
 
 
 # Record for storing permission, attribute, etc. bits from a PTE
 class PermAttr(RecordObject):
-    def __init__(self):
-        super().__init__()
+    def __init__(self, name=None):
+        super().__init__(name=name)
         self.reference = Signal()
         self.changed   = Signal()
         self.nocache   = Signal()
@@ -230,12 +274,6 @@ class PermAttr(RecordObject):
 
 def extract_perm_attr(pte):
     pa = PermAttr()
-    pa.reference = pte[8]
-    pa.changed   = pte[7]
-    pa.nocache   = pte[5]
-    pa.priv      = pte[3]
-    pa.rd_perm   = pte[2]
-    pa.wr_perm   = pte[1]
     return pa;
 
 
@@ -279,9 +317,9 @@ class State(Enum):
 # Stage 0 register, basically contains just the latched request
 
 class RegStage0(RecordObject):
-    def __init__(self):
-        super().__init__()
-        self.req     = LoadStore1ToDCacheType()
+    def __init__(self, name=None):
+        super().__init__(name=name)
+        self.req     = LoadStore1ToDCacheType(name="lsmem")
         self.tlbie   = Signal()
         self.doall   = Signal()
         self.tlbld   = Signal()
@@ -289,8 +327,8 @@ class RegStage0(RecordObject):
 
 
 class MemAccessRequest(RecordObject):
-    def __init__(self):
-        super().__init__()
+    def __init__(self, name=None):
+        super().__init__(name=name)
         self.op        = Signal(Op)
         self.valid     = Signal()
         self.dcbz      = Signal()
@@ -305,17 +343,17 @@ class MemAccessRequest(RecordObject):
 # First stage register, contains state for stage 1 of load hits
 # and for the state machine used by all other operations
 class RegStage1(RecordObject):
-    def __init__(self):
-        super().__init__()
+    def __init__(self, name=None):
+        super().__init__(name=name)
         # Info about the request
         self.full             = Signal() # have uncompleted request
         self.mmu_req          = Signal() # request is from MMU
-        self.req              = MemAccessRequest()
+        self.req              = MemAccessRequest(name="reqmem")
 
         # Cache hit state
         self.hit_way          = Signal(WAY_BITS)
         self.hit_load_valid   = Signal()
-        self.hit_index        = Signal(NUM_LINES)
+        self.hit_index        = Signal(INDEX_BITS)
         self.cache_hit        = Signal()
 
         # TLB hit state
@@ -339,12 +377,13 @@ class RegStage1(RecordObject):
         self.write_bram       = Signal()
         self.write_tag        = Signal()
         self.slow_valid       = Signal()
-        self.wb               = WBMasterOut()
+        self.real_adr         = Signal(REAL_ADDR_BITS)
+        self.wb               = WBMasterOut("wb")
         self.reload_tag       = Signal(TAG_BITS)
         self.store_way        = Signal(WAY_BITS)
         self.store_row        = Signal(ROW_BITS)
         self.store_index      = Signal(INDEX_BITS)
-        self.end_row_ix       = Signal(log2_int(ROW_LINE_BITS, False))
+        self.end_row_ix       = Signal(ROW_LINE_BITS)
         self.rows_valid       = RowPerLineValidArray()
         self.acks_pending     = Signal(3)
         self.inc_acks         = Signal()
@@ -369,6 +408,162 @@ class Reservation(RecordObject):
         self.addr  = Signal(64-LINE_OFF_BITS)
 
 
+class DTLBUpdate(Elaboratable):
+    def __init__(self):
+        self.tlbie    = Signal()
+        self.tlbwe    = Signal()
+        self.doall    = Signal()
+        self.updated  = Signal()
+        self.v_updated  = Signal()
+        self.tlb_hit    = Signal()
+        self.tlb_req_index = Signal(TLB_SET_BITS)
+
+        self.tlb_hit_way     = Signal(TLB_WAY_BITS)
+        self.tlb_tag_way     = Signal(TLB_TAG_WAY_BITS)
+        self.tlb_pte_way     = Signal(TLB_PTE_WAY_BITS)
+        self.repl_way        = Signal(TLB_WAY_BITS)
+        self.eatag           = Signal(TLB_EA_TAG_BITS)
+        self.pte_data        = Signal(TLB_PTE_BITS)
+
+        self.dv = Signal(TLB_PTE_WAY_BITS)
+
+        self.tb_out = Signal(TLB_TAG_WAY_BITS)
+        self.pb_out = Signal(TLB_NUM_WAYS)
+        self.db_out = Signal(TLB_PTE_WAY_BITS)
+
+    def elaborate(self, platform):
+        m = Module()
+        comb = m.d.comb
+        sync = m.d.sync
+
+        tagset   = Signal(TLB_TAG_WAY_BITS)
+        pteset   = Signal(TLB_PTE_WAY_BITS)
+
+        tb_out, pb_out, db_out = self.tb_out, self.pb_out, self.db_out
+
+        with m.If(self.tlbie & self.doall):
+            pass # clear all back in parent
+        with m.Elif(self.tlbie):
+            with m.If(self.tlb_hit):
+                comb += db_out.eq(self.dv)
+                comb += db_out.bit_select(self.tlb_hit_way, 1).eq(1)
+                comb += self.v_updated.eq(1)
+
+        with m.Elif(self.tlbwe):
+
+            comb += tagset.eq(self.tlb_tag_way)
+            comb += write_tlb_tag(self.repl_way, tagset, self.eatag)
+            comb += tb_out.eq(tagset)
+
+            comb += pteset.eq(self.tlb_pte_way)
+            comb += write_tlb_pte(self.repl_way, pteset, self.pte_data)
+            comb += pb_out.eq(pteset)
+
+            comb += db_out.bit_select(self.repl_way, 1).eq(1)
+
+            comb += self.updated.eq(1)
+            comb += self.v_updated.eq(1)
+
+        return m
+
+
+class DCachePendingHit(Elaboratable):
+
+    def __init__(self, tlb_pte_way, tlb_valid_way, tlb_hit_way,
+                      cache_valid_idx, cache_tag_set,
+                    req_addr,
+                    hit_set):
+
+        self.go          = Signal()
+        self.virt_mode   = Signal()
+        self.is_hit      = Signal()
+        self.tlb_hit     = Signal()
+        self.hit_way     = Signal(WAY_BITS)
+        self.rel_match   = Signal()
+        self.req_index   = Signal(INDEX_BITS)
+        self.reload_tag  = Signal(TAG_BITS)
+
+        self.tlb_hit_way = tlb_hit_way
+        self.tlb_pte_way = tlb_pte_way
+        self.tlb_valid_way = tlb_valid_way
+        self.cache_valid_idx = cache_valid_idx
+        self.cache_tag_set = cache_tag_set
+        self.req_addr = req_addr
+        self.hit_set = hit_set
+
+    def elaborate(self, platform):
+        m = Module()
+        comb = m.d.comb
+        sync = m.d.sync
+
+        go = self.go
+        virt_mode = self.virt_mode
+        is_hit = self.is_hit
+        tlb_pte_way = self.tlb_pte_way
+        tlb_valid_way = self.tlb_valid_way
+        cache_valid_idx = self.cache_valid_idx
+        cache_tag_set = self.cache_tag_set
+        req_addr = self.req_addr
+        tlb_hit_way = self.tlb_hit_way
+        tlb_hit = self.tlb_hit
+        hit_set = self.hit_set
+        hit_way = self.hit_way
+        rel_match = self.rel_match
+        req_index = self.req_index
+        reload_tag = self.reload_tag
+
+        rel_matches = Array(Signal(name="rel_matches_%d" % i) \
+                                    for i in range(TLB_NUM_WAYS))
+        hit_way_set = HitWaySet()
+
+        # Test if pending request is a hit on any way
+        # In order to make timing in virtual mode,
+        # when we are using the TLB, we compare each
+        # way with each of the real addresses from each way of
+        # the TLB, and then decide later which match to use.
+
+        with m.If(virt_mode):
+            for j in range(TLB_NUM_WAYS):
+                s_tag       = Signal(TAG_BITS, name="s_tag%d" % j)
+                s_hit       = Signal()
+                s_pte       = Signal(TLB_PTE_BITS)
+                s_ra        = Signal(REAL_ADDR_BITS)
+                comb += s_pte.eq(read_tlb_pte(j, tlb_pte_way))
+                comb += s_ra.eq(Cat(req_addr[0:TLB_LG_PGSZ],
+                                    s_pte[TLB_LG_PGSZ:REAL_ADDR_BITS]))
+                comb += s_tag.eq(get_tag(s_ra))
+
+                for i in range(NUM_WAYS):
+                    is_tag_hit = Signal(name="is_tag_hit_%d_%d" % (j, i))
+                    comb += is_tag_hit.eq(go & cache_valid_idx[i] &
+                                  (read_tag(i, cache_tag_set) == s_tag)
+                                  & tlb_valid_way[j])
+                    with m.If(is_tag_hit):
+                        comb += hit_way_set[j].eq(i)
+                        comb += s_hit.eq(1)
+                comb += hit_set[j].eq(s_hit)
+                with m.If(s_tag == reload_tag):
+                    comb += rel_matches[j].eq(1)
+            with m.If(tlb_hit):
+                comb += is_hit.eq(hit_set[tlb_hit_way])
+                comb += hit_way.eq(hit_way_set[tlb_hit_way])
+                comb += rel_match.eq(rel_matches[tlb_hit_way])
+        with m.Else():
+            s_tag       = Signal(TAG_BITS)
+            comb += s_tag.eq(get_tag(req_addr))
+            for i in range(NUM_WAYS):
+                is_tag_hit = Signal(name="is_tag_hit_%d" % i)
+                comb += is_tag_hit.eq(go & cache_valid_idx[i] &
+                          (read_tag(i, cache_tag_set) == s_tag))
+                with m.If(is_tag_hit):
+                    comb += hit_way.eq(i)
+                    comb += is_hit.eq(1)
+            with m.If(s_tag == reload_tag):
+                comb += rel_match.eq(1)
+
+        return m
+
+
 class DCache(Elaboratable):
     """Set associative dcache write-through
     TODO (in no specific order):
@@ -378,11 +573,11 @@ class DCache(Elaboratable):
       while not idle...)
     """
     def __init__(self):
-        self.d_in      = LoadStore1ToDCacheType()
-        self.d_out     = DCacheToLoadStore1Type()
+        self.d_in      = LoadStore1ToDCacheType("d_in")
+        self.d_out     = DCacheToLoadStore1Type("d_out")
 
-        self.m_in      = MMUToDCacheType()
-        self.m_out     = DCacheToMMUType()
+        self.m_in      = MMUToDCacheType("m_in")
+        self.m_out     = DCacheToMMUType("m_out")
 
         self.stall_out = Signal()
 
@@ -398,12 +593,11 @@ class DCache(Elaboratable):
         sync = m.d.sync
         d_in, d_out, m_in = self.d_in, self.d_out, self.m_in
 
-        r = RegStage0()
+        r = RegStage0("stage0")
 
         # TODO, this goes in unit tests and formal proofs
-        with m.If(~(d_in.valid & m_in.valid)):
-            #sync += Display("request collision loadstore vs MMU")
-            pass
+        with m.If(d_in.valid & m_in.valid):
+            sync += Display("request collision loadstore vs MMU")
 
         with m.If(m_in.valid):
             sync += r.req.valid.eq(1)
@@ -411,7 +605,7 @@ class DCache(Elaboratable):
             sync += r.req.dcbz.eq(0)
             sync += r.req.nc.eq(0)
             sync += r.req.reserve.eq(0)
-            sync += r.req.virt_mode.eq(1)
+            sync += r.req.virt_mode.eq(0)
             sync += r.req.priv_mode.eq(1)
             sync += r.req.addr.eq(m_in.addr)
             sync += r.req.data.eq(m_in.pte)
@@ -460,33 +654,24 @@ class DCache(Elaboratable):
             sync += tlb_tag_way.eq(dtlb_tags[index])
             sync += tlb_pte_way.eq(dtlb_ptes[index])
 
-    def maybe_tlb_plrus(self, m, r1, tlb_plru_victim, acc, acc_en, lru):
+    def maybe_tlb_plrus(self, m, r1, tlb_plru_victim):
         """Generate TLB PLRUs
         """
         comb = m.d.comb
         sync = m.d.sync
 
-        with m.If(TLB_NUM_WAYS > 1):
-            for i in range(TLB_SET_SIZE):
-                # TLB PLRU interface
-                tlb_plru        = PLRU(TLB_WAY_BITS)
-                setattr(m.submodules, "maybe_plru_%d" % i, tlb_plru)
-                tlb_plru_acc    = Signal(TLB_WAY_BITS)
-                tlb_plru_acc_en = Signal()
-                tlb_plru_out    = Signal(TLB_WAY_BITS)
-
-                comb += tlb_plru.acc.eq(tlb_plru_acc)
-                comb += tlb_plru.acc_en.eq(tlb_plru_acc_en)
-                comb += tlb_plru.lru.eq(tlb_plru_out)
-
-                # PLRU interface
-                with m.If(r1.tlb_hit_index == i):
-                    comb += tlb_plru.acc_en.eq(r1.tlb_hit)
-                with m.Else():
-                    comb += tlb_plru.acc_en.eq(0)
-                comb += tlb_plru.acc.eq(r1.tlb_hit_way)
+        if TLB_NUM_WAYS == 0:
+            return
+        for i in range(TLB_SET_SIZE):
+            # TLB PLRU interface
+            tlb_plru        = PLRU(TLB_WAY_BITS)
+            setattr(m.submodules, "maybe_plru_%d" % i, tlb_plru)
+            tlb_plru_acc_en = Signal()
 
-                comb += tlb_plru_victim[i].eq(tlb_plru.lru)
+            comb += tlb_plru_acc_en.eq(r1.tlb_hit & (r1.tlb_hit_index == i))
+            comb += tlb_plru.acc_en.eq(tlb_plru_acc_en)
+            comb += tlb_plru.acc_i.eq(r1.tlb_hit_way)
+            comb += tlb_plru_victim[i].eq(tlb_plru.lru_o)
 
     def tlb_search(self, m, tlb_req_index, r0, r0_valid,
                    tlb_valid_way, tlb_tag_way, tlb_hit_way,
@@ -504,8 +689,10 @@ class DCache(Elaboratable):
         comb += eatag.eq(r0.req.addr[TLB_LG_END : 64 ])
 
         for i in range(TLB_NUM_WAYS):
-            with m.If(tlb_valid_way[i]
-                      & read_tlb_tag(i, tlb_tag_way) == eatag):
+            is_tag_hit = Signal()
+            comb += is_tag_hit.eq(tlb_valid_way[i]
+                                  & (read_tlb_tag(i, tlb_tag_way) == eatag))
+            with m.If(is_tag_hit):
                 comb += hitway.eq(i)
                 comb += hit.eq(1)
 
@@ -521,15 +708,20 @@ class DCache(Elaboratable):
             comb += ra.eq(Cat(Const(0, ROW_OFF_BITS),
                               r0.req.addr[ROW_OFF_BITS:TLB_LG_PGSZ],
                               pte[TLB_LG_PGSZ:REAL_ADDR_BITS]))
-            comb += perm_attr.eq(extract_perm_attr(pte))
+            comb += perm_attr.reference.eq(pte[8])
+            comb += perm_attr.changed.eq(pte[7])
+            comb += perm_attr.nocache.eq(pte[5])
+            comb += perm_attr.priv.eq(pte[3])
+            comb += perm_attr.rd_perm.eq(pte[2])
+            comb += perm_attr.wr_perm.eq(pte[1])
         with m.Else():
             comb += ra.eq(Cat(Const(0, ROW_OFF_BITS),
                               r0.req.addr[ROW_OFF_BITS:REAL_ADDR_BITS]))
 
             comb += perm_attr.reference.eq(1)
             comb += perm_attr.changed.eq(1)
-            comb += perm_attr.priv.eq(1)
             comb += perm_attr.nocache.eq(0)
+            comb += perm_attr.priv.eq(1)
             comb += perm_attr.rd_perm.eq(1)
             comb += perm_attr.wr_perm.eq(1)
 
@@ -542,38 +734,38 @@ class DCache(Elaboratable):
 
         tlbie    = Signal()
         tlbwe    = Signal()
-        repl_way = Signal(TLB_WAY_BITS)
-        eatag    = Signal(TLB_EA_TAG_BITS)
-        tagset   = Signal(TLB_TAG_WAY_BITS)
-        pteset   = Signal(TLB_PTE_WAY_BITS)
-
-        vb = Signal(TLB_NUM_WAYS)
 
         comb += tlbie.eq(r0_valid & r0.tlbie)
         comb += tlbwe.eq(r0_valid & r0.tlbld)
-        sync += vb.eq(dtlb_valid_bits[tlb_req_index])
 
+        m.submodules.tlb_update = d = DTLBUpdate()
         with m.If(tlbie & r0.doall):
             # clear all valid bits at once
             for i in range(TLB_SET_SIZE):
                 sync += dtlb_valid_bits[i].eq(0)
+        with m.If(d.updated):
+            sync += dtlb_tags[tlb_req_index].eq(d.tb_out)
+            sync += dtlb_ptes[tlb_req_index].eq(d.pb_out)
+        with m.If(d.v_updated):
+            sync += dtlb_valid_bits[tlb_req_index].eq(d.db_out)
+
+        comb += d.dv.eq(dtlb_valid_bits[tlb_req_index])
+
+        comb += d.tlbie.eq(tlbie)
+        comb += d.tlbwe.eq(tlbwe)
+        comb += d.doall.eq(r0.doall)
+        comb += d.tlb_hit.eq(tlb_hit)
+        comb += d.tlb_hit_way.eq(tlb_hit_way)
+        comb += d.tlb_tag_way.eq(tlb_tag_way)
+        comb += d.tlb_pte_way.eq(tlb_pte_way)
+        comb += d.tlb_req_index.eq(tlb_req_index)
 
-        with m.Elif(tlbie):
-            with m.If(tlb_hit):
-                sync += vb.bit_select(tlb_hit_way, 1).eq(Const(0, 1))
-        with m.Elif(tlbwe):
-            with m.If(tlb_hit):
-                comb += repl_way.eq(tlb_hit_way)
-            with m.Else():
-                comb += repl_way.eq(tlb_plru_victim[tlb_req_index])
-            comb += eatag.eq(r0.req.addr[TLB_LG_PGSZ + TLB_SET_BITS:64])
-            sync += tagset.eq(tlb_tag_way)
-            sync += write_tlb_tag(repl_way, tagset, eatag)
-            sync += dtlb_tags[tlb_req_index].eq(tagset)
-            sync += pteset.eq(tlb_pte_way)
-            sync += write_tlb_pte(repl_way, pteset, r0.req.data)
-            sync += dtlb_ptes[tlb_req_index].eq(pteset)
-            sync += vb.bit_select(repl_way, 1).eq(1)
+        with m.If(tlb_hit):
+            comb += d.repl_way.eq(tlb_hit_way)
+        with m.Else():
+            comb += d.repl_way.eq(tlb_plru_victim[tlb_req_index])
+        comb += d.eatag.eq(r0.req.addr[TLB_LG_PGSZ + TLB_SET_BITS:64])
+        comb += d.pte_data.eq(r0.req.data)
 
     def maybe_plrus(self, m, r1, plru_victim):
         """Generate PLRUs
@@ -581,23 +773,19 @@ class DCache(Elaboratable):
         comb = m.d.comb
         sync = m.d.sync
 
+        if TLB_NUM_WAYS == 0:
+            return
+
         for i in range(NUM_LINES):
             # PLRU interface
-            plru        = PLRU(TLB_WAY_BITS)
+            plru        = PLRU(WAY_BITS)
             setattr(m.submodules, "plru%d" % i, plru)
-            plru_acc    = Signal(WAY_BITS)
             plru_acc_en = Signal()
-            plru_out    = Signal(WAY_BITS)
 
-            comb += plru.acc.eq(plru_acc)
+            comb += plru_acc_en.eq(r1.cache_hit & (r1.hit_index == i))
             comb += plru.acc_en.eq(plru_acc_en)
-            comb += plru_out.eq(plru.lru_o)
-
-            with m.If(r1.hit_index == i):
-                comb += plru_acc_en.eq(r1.cache_hit)
-
-            comb += plru_acc.eq(r1.hit_way)
-            comb += plru_victim[i].eq(plru_out)
+            comb += plru.acc_i.eq(r1.hit_way)
+            comb += plru_victim[i].eq(plru.lru_o)
 
     def cache_tag_read(self, m, r0_stall, req_index, cache_tag_set, cache_tags):
         """Cache tag RAM read port
@@ -617,7 +805,7 @@ class DCache(Elaboratable):
         sync += cache_tag_set.eq(cache_tags[index])
 
     def dcache_request(self, m, r0, ra, req_index, req_row, req_tag,
-                       r0_valid, r1, cache_valid_bits, replace_way,
+                       r0_valid, r1, cache_valids, replace_way,
                        use_forward1_next, use_forward2_next,
                        req_hit_way, plru_victim, rc_ok, perm_attr,
                        valid_ra, perm_ok, access_ok, req_op, req_go,
@@ -637,72 +825,50 @@ class DCache(Elaboratable):
         opsel       = Signal(3)
         go          = Signal()
         nc          = Signal()
-        s_hit       = Signal()
-        s_tag       = Signal(TAG_BITS)
-        s_pte       = Signal(TLB_PTE_BITS)
-        s_ra        = Signal(REAL_ADDR_BITS)
-        hit_set     = Signal(TLB_NUM_WAYS)
-        hit_way_set = HitWaySet()
-        rel_matches = Signal(TLB_NUM_WAYS)
-        rel_match   = Signal()
+        hit_set     = Array(Signal(name="hit_set_%d" % i) \
+                                  for i in range(TLB_NUM_WAYS))
+        cache_valid_idx = Signal(NUM_WAYS)
 
         # Extract line, row and tag from request
         comb += req_index.eq(get_index(r0.req.addr))
         comb += req_row.eq(get_row(r0.req.addr))
         comb += req_tag.eq(get_tag(ra))
 
-        comb += go.eq(r0_valid & ~(r0.tlbie | r0.tlbld) & ~r1.ls_error)
-
-        # Test if pending request is a hit on any way
-        # In order to make timing in virtual mode,
-        # when we are using the TLB, we compare each
-        # way with each of the real addresses from each way of
-        # the TLB, and then decide later which match to use.
-
-        with m.If(r0.req.virt_mode):
-            comb += rel_matches.eq(0)
-            for j in range(TLB_NUM_WAYS):
-                comb += s_pte.eq(read_tlb_pte(j, tlb_pte_way))
-                comb += s_ra.eq(Cat(r0.req.addr[0:TLB_LG_PGSZ],
-                                    s_pte[TLB_LG_PGSZ:REAL_ADDR_BITS]))
-                comb += s_tag.eq(get_tag(s_ra))
+        if False: # display on comb is a bit... busy.
+            comb += Display("dcache_req addr:%x ra: %x idx: %x tag: %x row: %x",
+                    r0.req.addr, ra, req_index, req_tag, req_row)
 
-                for i in range(NUM_WAYS):
-                    with m.If(go & cache_valid_bits[req_index][i] &
-                              read_tag(i, cache_tag_set) == s_tag
-                              & tlb_valid_way[j]):
-                        comb += hit_way_set[j].eq(i)
-                        comb += s_hit.eq(1)
-                comb += hit_set[j].eq(s_hit)
-                with m.If(s_tag == r1.reload_tag):
-                    comb += rel_matches[j].eq(1)
-            with m.If(tlb_hit):
-                comb += is_hit.eq(hit_set.bit_select(tlb_hit_way, 1))
-                comb += hit_way.eq(hit_way_set[tlb_hit_way])
-                comb += rel_match.eq(rel_matches.bit_select(tlb_hit_way, 1))
-        with m.Else():
-            comb += s_tag.eq(get_tag(r0.req.addr))
-            for i in range(NUM_WAYS):
-                with m.If(go & cache_valid_bits[req_index][i] &
-                          read_tag(i, cache_tag_set) == s_tag):
-                    comb += hit_way.eq(i)
-                    comb += is_hit.eq(1)
-            with m.If(s_tag == r1.reload_tag):
-                comb += rel_match.eq(1)
-        comb += req_same_tag.eq(rel_match)
+        comb += go.eq(r0_valid & ~(r0.tlbie | r0.tlbld) & ~r1.ls_error)
+        comb += cache_valid_idx.eq(cache_valids[req_index])
+
+        m.submodules.dcache_pend = dc = DCachePendingHit(tlb_pte_way,
+                                tlb_valid_way, tlb_hit_way,
+                                cache_valid_idx, cache_tag_set,
+                                r0.req.addr,
+                                hit_set)
+
+        comb += dc.tlb_hit.eq(tlb_hit)
+        comb += dc.reload_tag.eq(r1.reload_tag)
+        comb += dc.virt_mode.eq(r0.req.virt_mode)
+        comb += dc.go.eq(go)
+        comb += dc.req_index.eq(req_index)
+        comb += is_hit.eq(dc.is_hit)
+        comb += hit_way.eq(dc.hit_way)
+        comb += req_same_tag.eq(dc.rel_match)
 
         # See if the request matches the line currently being reloaded
         with m.If((r1.state == State.RELOAD_WAIT_ACK) &
-                  (req_index == r1.store_index) & rel_match):
+                  (req_index == r1.store_index) & req_same_tag):
             # For a store, consider this a hit even if the row isn't
             # valid since it will be by the time we perform the store.
             # For a load, check the appropriate row valid bit.
-            valid = r1.rows_valid[req_row % ROW_PER_LINE]
+            rrow = Signal(ROW_LINE_BITS)
+            comb += rrow.eq(req_row)
+            valid = r1.rows_valid[rrow]
             comb += is_hit.eq(~r0.req.load | valid)
             comb += hit_way.eq(replace_way)
 
         # Whether to use forwarded data for a load or not
-        comb += use_forward1_next.eq(0)
         with m.If((get_row(r1.req.real_addr) == req_row) &
                   (r1.req.hit_way == hit_way)):
             # Only need to consider r1.write_bram here, since if we
@@ -714,7 +880,6 @@ class DCache(Elaboratable):
             # cycles after the refill starts before we see the updated
             # cache tag. In that case we don't use the bypass.)
             comb += use_forward1_next.eq(r1.write_bram)
-        comb += use_forward2_next.eq(0)
         with m.If((r1.forward_row1 == req_row) & (r1.forward_way1 == hit_way)):
             comb += use_forward2_next.eq(r1.forward_valid1)
 
@@ -723,7 +888,7 @@ class DCache(Elaboratable):
 
         # The way to replace on a miss
         with m.If(r1.write_tag):
-            replace_way.eq(plru_victim[r1.store_index])
+            comb += replace_way.eq(plru_victim[r1.store_index])
         with m.Else():
             comb += replace_way.eq(r1.store_way)
 
@@ -732,10 +897,9 @@ class DCache(Elaboratable):
         comb += rc_ok.eq(perm_attr.reference
                          & (r0.req.load | perm_attr.changed)
                 )
-        comb += perm_ok.eq((r0.req.priv_mode | ~perm_attr.priv)
-                           & perm_attr.wr_perm
-                           | (r0.req.load & perm_attr.rd_perm)
-                          )
+        comb += perm_ok.eq((r0.req.priv_mode | ~perm_attr.priv) &
+                           (perm_attr.wr_perm |
+                              (r0.req.load & perm_attr.rd_perm)))
         comb += access_ok.eq(valid_ra & perm_ok & rc_ok)
         # Combine the request and cache hit status to decide what
         # operation needs to be done
@@ -749,24 +913,14 @@ class DCache(Elaboratable):
             with m.Else():
                 comb += opsel.eq(Cat(is_hit, nc, r0.req.load))
                 with m.Switch(opsel):
-                    with m.Case(0b101):
-                        comb += op.eq(Op.OP_LOAD_HIT)
-                    with m.Case(0b100):
-                        comb += op.eq(Op.OP_LOAD_MISS)
-                    with m.Case(0b110):
-                        comb += op.eq(Op.OP_LOAD_NC)
-                    with m.Case(0b001):
-                        comb += op.eq(Op.OP_STORE_HIT)
-                    with m.Case(0b000):
-                        comb += op.eq(Op.OP_STORE_MISS)
-                    with m.Case(0b010):
-                        comb += op.eq(Op.OP_STORE_MISS)
-                    with m.Case(0b011):
-                        comb += op.eq(Op.OP_BAD)
-                    with m.Case(0b111):
-                        comb += op.eq(Op.OP_BAD)
-                    with m.Default():
-                        comb += op.eq(Op.OP_NONE)
+                    with m.Case(0b101): comb += op.eq(Op.OP_LOAD_HIT)
+                    with m.Case(0b100): comb += op.eq(Op.OP_LOAD_MISS)
+                    with m.Case(0b110): comb += op.eq(Op.OP_LOAD_NC)
+                    with m.Case(0b001): comb += op.eq(Op.OP_STORE_HIT)
+                    with m.Case(0b000): comb += op.eq(Op.OP_STORE_MISS)
+                    with m.Case(0b010): comb += op.eq(Op.OP_STORE_MISS)
+                    with m.Case(0b011): comb += op.eq(Op.OP_BAD)
+                    with m.Case(0b111): comb += op.eq(Op.OP_BAD)
         comb += req_op.eq(op)
         comb += req_go.eq(go)
 
@@ -790,14 +944,14 @@ class DCache(Elaboratable):
         sync = m.d.sync
 
         with m.If(r0_valid & r0.req.reserve):
-
             # XXX generate alignment interrupt if address
             # is not aligned XXX or if r0.req.nc = '1'
             with m.If(r0.req.load):
                 comb += set_rsrv.eq(1) # load with reservation
             with m.Else():
                 comb += clear_rsrv.eq(1) # store conditional
-                with m.If(~reservation.valid | r0.req.addr[LINE_OFF_BITS:64]):
+                with m.If(~reservation.valid |
+                         (r0.req.addr[LINE_OFF_BITS:64] != reservation.addr)):
                     comb += cancel_store.eq(1)
 
     def reservation_reg(self, m, r0_valid, access_ok, set_rsrv, clear_rsrv,
@@ -813,7 +967,7 @@ class DCache(Elaboratable):
                 sync += reservation.valid.eq(1)
                 sync += reservation.addr.eq(r0.req.addr[LINE_OFF_BITS:64])
 
-    def writeback_control(self, m, r1, cache_out):
+    def writeback_control(self, m, r1, cache_out_row):
         """Return data for loads & completion control logic
         """
         comb = m.d.comb
@@ -832,7 +986,7 @@ class DCache(Elaboratable):
         with m.Else():
             comb += data_fwd.eq(r1.forward_data2)
 
-        comb += data_out.eq(cache_out[r1.hit_way])
+        comb += data_out.eq(cache_out_row)
 
         for i in range(8):
             with m.If(r1.forward_sel[i]):
@@ -873,35 +1027,32 @@ class DCache(Elaboratable):
             # Request came from loadstore1...
             # Load hit case is the standard path
             with m.If(r1.hit_load_valid):
-                #Display(f"completing load hit data={data_out}")
-                pass
+                sync += Display("completing load hit data=%x", data_out)
 
             # error cases complete without stalling
             with m.If(r1.ls_error):
-                # Display("completing ld/st with error")
-                pass
+                sync += Display("completing ld/st with error")
 
             # Slow ops (load miss, NC, stores)
             with m.If(r1.slow_valid):
-                #Display(f"completing store or load miss data={data_out}")
-                pass
+                sync += Display("completing store or load miss data=%x",
+                                data_out)
 
         with m.Else():
             # Request came from MMU
             with m.If(r1.hit_load_valid):
-                # Display(f"completing load hit to MMU, data={m_out.data}")
-                pass
+                sync += Display("completing load hit to MMU, data=%x",
+                                m_out.data)
             # error cases complete without stalling
             with m.If(r1.mmu_error):
-                #Display("combpleting MMU ld with error")
-                pass
+                sync += Display("combpleting MMU ld with error")
 
             # Slow ops (i.e. load miss)
             with m.If(r1.slow_valid):
-                #Display("completing MMU load miss, data={m_out.data}")
-                pass
+                sync += Display("completing MMU load miss, data=%x",
+                                m_out.data)
 
-    def rams(self, m, r1, early_req_row, cache_out, replace_way):
+    def rams(self, m, r1, early_req_row, cache_out_row, replace_way):
         """rams
         Generate a cache RAM for each way. This handles the normal
         reads, writes from reloads and the special store-hit update
@@ -916,16 +1067,16 @@ class DCache(Elaboratable):
         wb_in = self.wb_in
 
         for i in range(NUM_WAYS):
-            do_read  = Signal()
+            do_read  = Signal(name="do_rd%d" % i)
             rd_addr  = Signal(ROW_BITS)
-            do_write = Signal()
+            do_write = Signal(name="do_wr%d" % i)
             wr_addr  = Signal(ROW_BITS)
             wr_data  = Signal(WB_DATA_BITS)
             wr_sel   = Signal(ROW_SIZE)
             wr_sel_m = Signal(ROW_SIZE)
-            _d_out   = Signal(WB_DATA_BITS)
+            _d_out   = Signal(WB_DATA_BITS, name="dout_%d" % i)
 
-            way = CacheRam(ROW_BITS, WB_DATA_BITS, True)
+            way = CacheRam(ROW_BITS, WB_DATA_BITS, ADD_BUF=True)
             setattr(m.submodules, "cacheram_%d" % i, way)
 
             comb += way.rd_en.eq(do_read)
@@ -937,8 +1088,9 @@ class DCache(Elaboratable):
 
             # Cache hit reads
             comb += do_read.eq(1)
-            comb += rd_addr.eq(early_req_row)
-            comb += cache_out[i].eq(_d_out)
+            comb += rd_addr.eq(early_req_row[:ROW_BITS])
+            with m.If(r1.hit_way == i):
+                comb += cache_out_row.eq(_d_out)
 
             # Write mux:
             #
@@ -969,26 +1121,25 @@ class DCache(Elaboratable):
                       & wb_in.ack & (replace_way == i)):
                 comb += do_write.eq(1)
 
-                # Mask write selects with do_write since BRAM
-                # doesn't have a global write-enable
-                with m.If(do_write):
-                    comb += wr_sel_m.eq(wr_sel)
+            # Mask write selects with do_write since BRAM
+            # doesn't have a global write-enable
+            with m.If(do_write):
+                comb += wr_sel_m.eq(wr_sel)
 
     # Cache hit synchronous machine for the easy case.
     # This handles load hits.
     # It also handles error cases (TLB miss, cache paradox)
     def dcache_fast_hit(self, m, req_op, r0_valid, r0, r1,
-                        req_hit_way, req_index, access_ok,
+                        req_hit_way, req_index, req_tag, access_ok,
                         tlb_hit, tlb_hit_way, tlb_req_index):
 
         comb = m.d.comb
         sync = m.d.sync
 
         with m.If(req_op != Op.OP_NONE):
-            #Display(f"op:{req_op} addr:{r0.req.addr} nc: {r0.req.nc}" \
-            #      f"idx:{req_index} tag:{req_tag} way: {req_hit_way}"
-            #     )
-            pass
+            sync += Display("op:%d addr:%x nc: %d idx: %x tag: %x way: %x",
+                    req_op, r0.req.addr, r0.req.nc,
+                    req_index, req_tag, req_hit_way)
 
         with m.If(r0_valid):
             sync += r1.mmu_req.eq(r0.mmu_req)
@@ -1039,18 +1190,24 @@ class DCache(Elaboratable):
     # All wishbone requests generation is done here.
     # This machine operates at stage 1.
     def dcache_slow(self, m, r1, use_forward1_next, use_forward2_next,
-                    cache_valid_bits, r0, replace_way,
+                    cache_valids, r0, replace_way,
                     req_hit_way, req_same_tag,
-                    r0_valid, req_op, cache_tag, req_go, ra):
+                    r0_valid, req_op, cache_tags, req_go, ra):
 
         comb = m.d.comb
         sync = m.d.sync
         wb_in = self.wb_in
 
-        req         = MemAccessRequest()
+        req         = MemAccessRequest("mreq_ds")
         acks        = Signal(3)
         adjust_acks = Signal(3)
-        stbs_done = Signal()
+
+        req_row = Signal(ROW_BITS)
+        req_idx = Signal(INDEX_BITS)
+        req_tag = Signal(TAG_BITS)
+        comb += req_idx.eq(get_index(req.real_addr))
+        comb += req_row.eq(get_row(req.real_addr))
+        comb += req_tag.eq(get_tag(req.real_addr))
 
         sync += r1.use_forward1.eq(use_forward1_next)
         sync += r1.forward_sel.eq(0)
@@ -1099,8 +1256,9 @@ class DCache(Elaboratable):
             for i in range(NUM_WAYS):
                 with m.If(i == replace_way):
                     ct = Signal(TAG_RAM_WIDTH)
-                    sync += ct.eq(cache_tag[r1.store_index])
-                    sync += ct.word_select(i, TAG_WIDTH).eq(r1.reload_tag)
+                    comb += ct.eq(cache_tags[r1.store_index])
+                    comb += ct.word_select(i, TAG_WIDTH).eq(r1.reload_tag)
+                    sync += cache_tags[r1.store_index].eq(ct)
             sync += r1.store_way.eq(replace_way)
             sync += r1.write_tag.eq(0)
 
@@ -1143,23 +1301,17 @@ class DCache(Elaboratable):
         with m.Switch(r1.state):
 
             with m.Case(State.IDLE):
-# XXX check 'left downto.  probably means len(r1.wb.adr)
-#                     r1.wb.adr <= req.real_addr(
-#                                   r1.wb.adr'left downto 0
-#                                  );
-                sync += r1.wb.adr.eq(req.real_addr)
+                sync += r1.real_adr.eq(req.real_addr)
                 sync += r1.wb.sel.eq(req.byte_sel)
                 sync += r1.wb.dat.eq(req.data)
                 sync += r1.dcbz.eq(req.dcbz)
 
                 # Keep track of our index and way
                 # for subsequent stores.
-                sync += r1.store_index.eq(get_index(req.real_addr))
-                sync += r1.store_row.eq(get_row(req.real_addr))
-                sync += r1.end_row_ix.eq(
-                         get_row_of_line(get_row(req.real_addr))
-                        )
-                sync += r1.reload_tag.eq(get_tag(req.real_addr))
+                sync += r1.store_index.eq(req_idx)
+                sync += r1.store_row.eq(req_row)
+                sync += r1.end_row_ix.eq(get_row_of_line(req_row))
+                sync += r1.reload_tag.eq(req_tag)
                 sync += r1.req.same_tag.eq(1)
 
                 with m.If(req.op == Op.OP_STORE_HIT):
@@ -1170,17 +1322,18 @@ class DCache(Elaboratable):
                 for i in range(ROW_PER_LINE):
                     sync += r1.rows_valid[i].eq(0)
 
+                with m.If(req_op != Op.OP_NONE):
+                    sync += Display("cache op %d", req.op)
+
                 with m.Switch(req.op):
                     with m.Case(Op.OP_LOAD_HIT):
                         # stay in IDLE state
                         pass
 
                     with m.Case(Op.OP_LOAD_MISS):
-                        #Display(f"cache miss real addr:" \
-                        #      f"{req_real_addr}" \
-                        #      f" idx:{get_index(req_real_addr)}" \
-                        #      f" tag:{get_tag(req.real_addr)}")
-                        pass
+                        sync += Display("cache miss real addr: %x " \
+                                "idx: %x tag: %x",
+                                req.real_addr, req_row, req_tag)
 
                         # Start the wishbone cycle
                         sync += r1.wb.we.eq(0)
@@ -1212,6 +1365,8 @@ class DCache(Elaboratable):
                             with m.If(req.op == Op.OP_STORE_HIT):
                                 sync += r1.write_bram.eq(1)
                         with m.Else():
+                            # dcbz is handled much like a load miss except
+                            # that we are writing to memory instead of reading
                             sync += r1.state.eq(State.RELOAD_WAIT_ACK)
 
                             with m.If(req.op == Op.OP_STORE_MISS):
@@ -1232,29 +1387,31 @@ class DCache(Elaboratable):
                         pass
 
             with m.Case(State.RELOAD_WAIT_ACK):
+                ld_stbs_done = Signal()
                 # Requests are all sent if stb is 0
-                comb += stbs_done.eq(~r1.wb.stb)
+                comb += ld_stbs_done.eq(~r1.wb.stb)
 
-                with m.If(~wb_in.stall & ~stbs_done):
+                with m.If((~wb_in.stall) & r1.wb.stb):
                     # That was the last word?
                     # We are done sending.
-                    # Clear stb and set stbs_done
+                    # Clear stb and set ld_stbs_done
                     # so we can handle an eventual
                     # last ack on the same cycle.
-                    with m.If(is_last_row_addr(
-                              r1.wb.adr, r1.end_row_ix)):
+                    with m.If(is_last_row_addr(r1.real_adr, r1.end_row_ix)):
                         sync += r1.wb.stb.eq(0)
-                        comb += stbs_done.eq(0)
+                        comb += ld_stbs_done.eq(1)
 
                     # Calculate the next row address in the current cache line
-                    rarange = r1.wb.adr[ROW_OFF_BITS : LINE_OFF_BITS]
-                    sync += rarange.eq(rarange + 1)
+                    row = Signal(LINE_OFF_BITS-ROW_OFF_BITS)
+                    comb += row.eq(r1.real_adr[ROW_OFF_BITS:])
+                    sync += r1.real_adr[ROW_OFF_BITS:LINE_OFF_BITS].eq(row+1)
 
                 # Incoming acks processing
                 sync += r1.forward_valid1.eq(wb_in.ack)
                 with m.If(wb_in.ack):
-                    # XXX needs an Array bit-accessor here
-                    sync += r1.rows_valid[r1.store_row % ROW_PER_LINE].eq(1)
+                    srow = Signal(ROW_LINE_BITS)
+                    comb += srow.eq(r1.store_row)
+                    sync += r1.rows_valid[srow].eq(1)
 
                     # If this is the data we were looking for,
                     # we can complete the request next cycle.
@@ -1275,22 +1432,24 @@ class DCache(Elaboratable):
                         sync += r1.use_forward1.eq(1)
 
                     # Check for completion
-                    with m.If(stbs_done & is_last_row(r1.store_row,
+                    with m.If(ld_stbs_done & is_last_row(r1.store_row,
                                                       r1.end_row_ix)):
                         # Complete wishbone cycle
                         sync += r1.wb.cyc.eq(0)
 
                         # Cache line is now valid
                         cv = Signal(INDEX_BITS)
-                        sync += cv.eq(cache_valid_bits[r1.store_index])
-                        sync += cv.bit_select(r1.store_way, 1).eq(1)
+                        comb += cv.eq(cache_valids[r1.store_index])
+                        comb += cv.bit_select(r1.store_way, 1).eq(1)
+                        sync += cache_valids[r1.store_index].eq(cv)
                         sync += r1.state.eq(State.IDLE)
 
                     # Increment store row counter
                     sync += r1.store_row.eq(next_row(r1.store_row))
 
             with m.Case(State.STORE_WAIT_ACK):
-                comb += stbs_done.eq(~r1.wb.stb)
+                st_stbs_done = Signal()
+                comb += st_stbs_done.eq(~r1.wb.stb)
                 comb += acks.eq(r1.acks_pending)
 
                 with m.If(r1.inc_acks != r1.dec_acks):
@@ -1309,7 +1468,7 @@ class DCache(Elaboratable):
                     # to be done which is in the same real page.
                     with m.If(req.valid):
                         ra = req.real_addr[0:SET_SIZE_BITS]
-                        sync += r1.wb.adr[0:SET_SIZE_BITS].eq(ra)
+                        sync += r1.real_adr[0:SET_SIZE_BITS].eq(ra)
                         sync += r1.wb.dat.eq(req.data)
                         sync += r1.wb.sel.eq(req.byte_sel)
 
@@ -1317,7 +1476,7 @@ class DCache(Elaboratable):
                                 ((req.op == Op.OP_STORE_MISS)
                                  | (req.op == Op.OP_STORE_HIT))):
                         sync += r1.wb.stb.eq(1)
-                        comb += stbs_done.eq(0)
+                        comb += st_stbs_done.eq(0)
 
                         with m.If(req.op == Op.OP_STORE_HIT):
                             sync += r1.write_bram.eq(1)
@@ -1326,15 +1485,15 @@ class DCache(Elaboratable):
 
                         # Store requests never come from the MMU
                         sync += r1.ls_valid.eq(1)
-                        comb += stbs_done.eq(0)
+                        comb += st_stbs_done.eq(0)
                         sync += r1.inc_acks.eq(1)
                     with m.Else():
                         sync += r1.wb.stb.eq(0)
-                        comb += stbs_done.eq(1)
+                        comb += st_stbs_done.eq(1)
 
                 # Got ack ? See if complete.
                 with m.If(wb_in.ack):
-                    with m.If(stbs_done & (adjust_acks == 1)):
+                    with m.If(st_stbs_done & (adjust_acks == 1)):
                         sync += r1.state.eq(State.IDLE)
                         sync += r1.wb.cyc.eq(0)
                         sync += r1.wb.stb.eq(0)
@@ -1369,7 +1528,7 @@ class DCache(Elaboratable):
         sync += log_out.eq(Cat(r1.state[:3], valid_ra, tlb_hit_way[:3],
                                stall_out, req_op[:3], d_out.valid, d_out.error,
                                r1.wb.cyc, r1.wb.stb, wb_in.ack, wb_in.stall,
-                               r1.wb.adr[3:6]))
+                               r1.real_adr[3:6]))
 
     def elaborate(self, platform):
 
@@ -1379,7 +1538,7 @@ class DCache(Elaboratable):
         # Storage. Hopefully "cache_rows" is a BRAM, the rest is LUTs
         cache_tags       = CacheTagArray()
         cache_tag_set    = Signal(TAG_RAM_WIDTH)
-        cache_valid_bits = CacheValidBitsArray()
+        cache_valids = CacheValidBitsArray()
 
         # TODO attribute ram_style : string;
         # TODO attribute ram_style of cache_tags : signal is "distributed";
@@ -1395,10 +1554,10 @@ class DCache(Elaboratable):
         # TODO attribute ram_style of
         #  dtlb_ptes : signal is "distributed";
 
-        r0      = RegStage0()
+        r0      = RegStage0("r0")
         r0_full = Signal()
 
-        r1 = RegStage1()
+        r1 = RegStage1("r1")
 
         reservation = Reservation()
 
@@ -1424,7 +1583,7 @@ class DCache(Elaboratable):
         use_forward1_next = Signal()
         use_forward2_next = Signal()
 
-        cache_out         = CacheRamOut()
+        cache_out_row     = Signal(WB_DATA_BITS)
 
         plru_victim       = PLRUOut()
         replace_way       = Signal(WAY_BITS)
@@ -1442,7 +1601,7 @@ class DCache(Elaboratable):
         pte           = Signal(TLB_PTE_BITS)
         ra            = Signal(REAL_ADDR_BITS)
         valid_ra      = Signal()
-        perm_attr     = PermAttr()
+        perm_attr     = PermAttr("dc_perms")
         rc_ok         = Signal()
         perm_ok       = Signal()
         access_ok     = Signal()
@@ -1459,6 +1618,7 @@ class DCache(Elaboratable):
         comb += self.stall_out.eq(r0_stall)
 
         # Wire up wishbone request latch out of stage 1
+        comb += r1.wb.adr.eq(r1.real_adr[ROW_OFF_BITS:]) # truncate LSBs
         comb += self.wb_out.eq(r1.wb)
 
         # call sub-functions putting everything together, using shared
@@ -1474,9 +1634,10 @@ class DCache(Elaboratable):
                         tlb_hit_way, tlb_hit, tlb_plru_victim, tlb_tag_way,
                         dtlb_tags, tlb_pte_way, dtlb_ptes)
         self.maybe_plrus(m, r1, plru_victim)
+        self.maybe_tlb_plrus(m, r1, tlb_plru_victim)
         self.cache_tag_read(m, r0_stall, req_index, cache_tag_set, cache_tags)
         self.dcache_request(m, r0, ra, req_index, req_row, req_tag,
-                           r0_valid, r1, cache_valid_bits, replace_way,
+                           r0_valid, r1, cache_valids, replace_way,
                            use_forward1_next, use_forward2_next,
                            req_hit_way, plru_victim, rc_ok, perm_attr,
                            valid_ra, perm_ok, access_ok, req_op, req_go,
@@ -1487,160 +1648,61 @@ class DCache(Elaboratable):
                            r0_valid, r0, reservation)
         self.reservation_reg(m, r0_valid, access_ok, set_rsrv, clear_rsrv,
                            reservation, r0)
-        self.writeback_control(m, r1, cache_out)
-        self.rams(m, r1, early_req_row, cache_out, replace_way)
+        self.writeback_control(m, r1, cache_out_row)
+        self.rams(m, r1, early_req_row, cache_out_row, replace_way)
         self.dcache_fast_hit(m, req_op, r0_valid, r0, r1,
-                        req_hit_way, req_index, access_ok,
+                        req_hit_way, req_index, req_tag, access_ok,
                         tlb_hit, tlb_hit_way, tlb_req_index)
         self.dcache_slow(m, r1, use_forward1_next, use_forward2_next,
-                    cache_valid_bits, r0, replace_way,
+                    cache_valids, r0, replace_way,
                     req_hit_way, req_same_tag,
                          r0_valid, req_op, cache_tags, req_go, ra)
         #self.dcache_log(m, r1, valid_ra, tlb_hit_way, stall_out)
 
         return m
 
+def dcache_load(dut, addr, nc=0):
+    yield dut.d_in.load.eq(1)
+    yield dut.d_in.nc.eq(nc)
+    yield dut.d_in.addr.eq(addr)
+    yield dut.d_in.byte_sel.eq(~0)
+    yield dut.d_in.valid.eq(1)
+    yield
+    yield dut.d_in.valid.eq(0)
+    yield dut.d_in.byte_sel.eq(0)
+    yield
+    while not (yield dut.d_out.valid):
+        yield
+    data = yield dut.d_out.data
+    return data
+
+
+def dcache_store(dut, addr, data, nc=0):
+    yield dut.d_in.load.eq(0)
+    yield dut.d_in.nc.eq(nc)
+    yield dut.d_in.data.eq(data)
+    yield dut.d_in.byte_sel.eq(~0)
+    yield dut.d_in.addr.eq(addr)
+    yield dut.d_in.valid.eq(1)
+    yield
+    yield dut.d_in.valid.eq(0)
+    yield dut.d_in.byte_sel.eq(0)
+    yield
+    while not (yield dut.d_out.valid):
+        yield
+
+
+def dcache_random_sim(dut):
+
+    # start with stack of zeros
+    sim_mem = [0] * 512
 
-# dcache_tb.vhdl
-#
-# entity dcache_tb is
-# end dcache_tb;
-#
-# architecture behave of dcache_tb is
-#     signal clk          : std_ulogic;
-#     signal rst          : std_ulogic;
-#
-#     signal d_in         : Loadstore1ToDcacheType;
-#     signal d_out        : DcacheToLoadstore1Type;
-#
-#     signal m_in         : MmuToDcacheType;
-#     signal m_out        : DcacheToMmuType;
-#
-#     signal wb_bram_in   : wishbone_master_out;
-#     signal wb_bram_out  : wishbone_slave_out;
-#
-#     constant clk_period : time := 10 ns;
-# begin
-#     dcache0: entity work.dcache
-#         generic map(
-#
-#             LINE_SIZE => 64,
-#             NUM_LINES => 4
-#             )
-#         port map(
-#             clk => clk,
-#             rst => rst,
-#             d_in => d_in,
-#             d_out => d_out,
-#             m_in => m_in,
-#             m_out => m_out,
-#             wishbone_out => wb_bram_in,
-#             wishbone_in => wb_bram_out
-#             );
-#
-#     -- BRAM Memory slave
-#     bram0: entity work.wishbone_bram_wrapper
-#         generic map(
-#             MEMORY_SIZE   => 1024,
-#             RAM_INIT_FILE => "icache_test.bin"
-#             )
-#         port map(
-#             clk => clk,
-#             rst => rst,
-#             wishbone_in => wb_bram_in,
-#             wishbone_out => wb_bram_out
-#             );
-#
-#     clk_process: process
-#     begin
-#         clk <= '0';
-#         wait for clk_period/2;
-#         clk <= '1';
-#         wait for clk_period/2;
-#     end process;
-#
-#     rst_process: process
-#     begin
-#         rst <= '1';
-#         wait for 2*clk_period;
-#         rst <= '0';
-#         wait;
-#     end process;
-#
-#     stim: process
-#     begin
-#     -- Clear stuff
-#     d_in.valid <= '0';
-#     d_in.load <= '0';
-#     d_in.nc <= '0';
-#     d_in.addr <= (others => '0');
-#     d_in.data <= (others => '0');
-#         m_in.valid <= '0';
-#         m_in.addr <= (others => '0');
-#         m_in.pte <= (others => '0');
-#
-#         wait for 4*clk_period;
-#     wait until rising_edge(clk);
-#
-#     -- Cacheable read of address 4
-#     d_in.load <= '1';
-#     d_in.nc <= '0';
-#         d_in.addr <= x"0000000000000004";
-#         d_in.valid <= '1';
-#     wait until rising_edge(clk);
-#         d_in.valid <= '0';
-#
-#     wait until rising_edge(clk) and d_out.valid = '1';
-#         assert d_out.data = x"0000000100000000"
-#         report "data @" & to_hstring(d_in.addr) &
-#         "=" & to_hstring(d_out.data) &
-#         " expected 0000000100000000"
-#         severity failure;
-# --      wait for clk_period;
-#
-#     -- Cacheable read of address 30
-#     d_in.load <= '1';
-#     d_in.nc <= '0';
-#         d_in.addr <= x"0000000000000030";
-#         d_in.valid <= '1';
-#     wait until rising_edge(clk);
-#         d_in.valid <= '0';
-#
-#     wait until rising_edge(clk) and d_out.valid = '1';
-#         assert d_out.data = x"0000000D0000000C"
-#         report "data @" & to_hstring(d_in.addr) &
-#         "=" & to_hstring(d_out.data) &
-#         " expected 0000000D0000000C"
-#         severity failure;
-#
-#     -- Non-cacheable read of address 100
-#     d_in.load <= '1';
-#     d_in.nc <= '1';
-#         d_in.addr <= x"0000000000000100";
-#         d_in.valid <= '1';
-#     wait until rising_edge(clk);
-#     d_in.valid <= '0';
-#     wait until rising_edge(clk) and d_out.valid = '1';
-#         assert d_out.data = x"0000004100000040"
-#         report "data @" & to_hstring(d_in.addr) &
-#         "=" & to_hstring(d_out.data) &
-#         " expected 0000004100000040"
-#         severity failure;
-#
-#     wait until rising_edge(clk);
-#     wait until rising_edge(clk);
-#     wait until rising_edge(clk);
-#     wait until rising_edge(clk);
-#
-#     std.env.finish;
-#     end process;
-# end;
-def dcache_sim(dut):
     # clear stuff
     yield dut.d_in.valid.eq(0)
     yield dut.d_in.load.eq(0)
+    yield dut.d_in.priv_mode.eq(1)
     yield dut.d_in.nc.eq(0)
-    yield dut.d_in.adrr.eq(0)
+    yield dut.d_in.addr.eq(0)
     yield dut.d_in.data.eq(0)
     yield dut.m_in.valid.eq(0)
     yield dut.m_in.addr.eq(0)
@@ -1650,48 +1712,97 @@ def dcache_sim(dut):
     yield
     yield
     yield
-    # wait_until rising_edge(clk)
-    yield
-    # Cacheable read of address 4
-    yield dut.d_in.load.eq(1)
+
+    print ()
+
+    for i in range(256):
+        addr = randint(0, 255)
+        data = randint(0, (1<<64)-1)
+        sim_mem[addr] = data
+        addr *= 8
+
+        print ("testing %x data %x" % (addr, data))
+
+        yield from dcache_load(dut, addr)
+        yield from dcache_store(dut, addr, data)
+
+        addr = randint(0, 255)
+        sim_data = sim_mem[addr]
+        addr *= 8
+
+        data = yield from dcache_load(dut, addr)
+        assert data == sim_data, \
+            "check %x data %x != %x" % (addr, data, sim_data)
+
+    for addr in range(256):
+        data = yield from dcache_load(dut, addr*8)
+        assert data == sim_mem[addr], \
+            "final check %x data %x != %x" % (addr*8, data, sim_mem[addr])
+
+def dcache_sim(dut):
+    # clear stuff
+    yield dut.d_in.valid.eq(0)
+    yield dut.d_in.load.eq(0)
+    yield dut.d_in.priv_mode.eq(1)
     yield dut.d_in.nc.eq(0)
-    yield dut.d_in.addr.eq(Const(0x0000000000000004, 64))
-    yield dut.d_in.valid.eq(1)
-    # wait-until rising_edge(clk)
+    yield dut.d_in.addr.eq(0)
+    yield dut.d_in.data.eq(0)
+    yield dut.m_in.valid.eq(0)
+    yield dut.m_in.addr.eq(0)
+    yield dut.m_in.pte.eq(0)
+    # wait 4 * clk_period
     yield
-    yield dut.d_in.valid.eq(0)
     yield
-    while not (yield dut.d_out.valid):
-        yield
-    assert dut.d_out.data == 0x0000000100000000, \
-        f"data @ {dut.d_in.addr}={dut.d_in.data} expected 0000000100000000"
+    yield
+    yield
+
+    # Cacheable read of address 4
+    data = yield from dcache_load(dut, 0x58)
+    addr = yield dut.d_in.addr
+    assert data == 0x0000001700000016, \
+        f"data @%x=%x expected 0x0000001700000016" % (addr, data)
 
+    # Cacheable read of address 20
+    data = yield from dcache_load(dut, 0x20)
+    addr = yield dut.d_in.addr
+    assert data == 0x0000000900000008, \
+        f"data @%x=%x expected 0x0000000900000008" % (addr, data)
 
     # Cacheable read of address 30
-    yield dut.d_in.load.eq(1)
-    yield dut.d_in.nc.eq(0)
-    yield dut.d_in.addr.eq(Const(0x0000000000000030, 64))
-    yield dut.d_in.valid.eq(1)
-    yield
-    yield dut.d_in.valid.eq(0)
-    yield
-    while not (yield dut.d_out.valid):
-        yield
-    assert dut.d_out.data == 0x0000000D0000000C, \
-        f"data @{dut.d_in.addr}={dut.d_out.data} expected 0000000D0000000C"
+    data = yield from dcache_load(dut, 0x530)
+    addr = yield dut.d_in.addr
+    assert data == 0x0000014D0000014C, \
+        f"data @%x=%x expected 0000014D0000014C" % (addr, data)
+
+    # 2nd Cacheable read of address 30
+    data = yield from dcache_load(dut, 0x530)
+    addr = yield dut.d_in.addr
+    assert data == 0x0000014D0000014C, \
+        f"data @%x=%x expected 0000014D0000014C" % (addr, data)
 
     # Non-cacheable read of address 100
-    yield dut.d_in.load.eq(1)
-    yield dut.d_in.nc.eq(1)
-    yield dut.d_in.addr.eq(Const(0x0000000000000100, 64))
-    yield dut.d_in.valid.eq(1)
-    yield
-    yield dut.d_in.valid.eq(0)
-    yield
-    while not (yield dut.d_out.valid):
-        yield
-    assert dut.d_out.data == 0x0000004100000040, \
-        f"data @ {dut.d_in.addr}={dut.d_out.data} expected 0000004100000040"
+    data = yield from dcache_load(dut, 0x100, nc=1)
+    addr = yield dut.d_in.addr
+    assert data == 0x0000004100000040, \
+        f"data @%x=%x expected 0000004100000040" % (addr, data)
+
+    # Store at address 530
+    yield from dcache_store(dut, 0x530, 0x121)
+
+    # Store at address 30
+    yield from dcache_store(dut, 0x530, 0x12345678)
+
+    # 3nd Cacheable read of address 530
+    data = yield from dcache_load(dut, 0x530)
+    addr = yield dut.d_in.addr
+    assert data == 0x12345678, \
+        f"data @%x=%x expected 0x12345678" % (addr, data)
+
+    # 4th Cacheable read of address 20
+    data = yield from dcache_load(dut, 0x20)
+    addr = yield dut.d_in.addr
+    assert data == 0x0000000900000008, \
+        f"data @%x=%x expected 0x0000000900000008" % (addr, data)
 
     yield
     yield
@@ -1699,14 +1810,44 @@ def dcache_sim(dut):
     yield
 
 
-def test_dcache():
+def test_dcache(mem, test_fn, test_name):
+    dut = DCache()
+
+    memory = Memory(width=64, depth=16*64, init=mem)
+    sram = SRAM(memory=memory, granularity=8)
+
+    m = Module()
+    m.submodules.dcache = dut
+    m.submodules.sram = sram
+
+    m.d.comb += sram.bus.cyc.eq(dut.wb_out.cyc)
+    m.d.comb += sram.bus.stb.eq(dut.wb_out.stb)
+    m.d.comb += sram.bus.we.eq(dut.wb_out.we)
+    m.d.comb += sram.bus.sel.eq(dut.wb_out.sel)
+    m.d.comb += sram.bus.adr.eq(dut.wb_out.adr)
+    m.d.comb += sram.bus.dat_w.eq(dut.wb_out.dat)
+
+    m.d.comb += dut.wb_in.ack.eq(sram.bus.ack)
+    m.d.comb += dut.wb_in.dat.eq(sram.bus.dat_r)
+
+    # nmigen Simulation
+    sim = Simulator(m)
+    sim.add_clock(1e-6)
+
+    sim.add_sync_process(wrap(test_fn(dut)))
+    with sim.write_vcd('test_dcache%s.vcd' % test_name):
+        sim.run()
+
+if __name__ == '__main__':
     dut = DCache()
     vl = rtlil.convert(dut, ports=[])
     with open("test_dcache.il", "w") as f:
         f.write(vl)
 
-    #run_simulation(dut, dcache_sim(), vcd_name='test_dcache.vcd')
+    mem = []
+    for i in range(0,512):
+        mem.append((i*2)| ((i*2+1)<<32))
 
-if __name__ == '__main__':
-    test_dcache()
+    test_dcache(mem, dcache_sim, "")
+    test_dcache(None, dcache_random_sim, "random")