From: Andreas Hansson <andreas.hansson@arm.com>
Date: Mon, 7 Jan 2013 18:05:38 +0000 (-0500)
Subject: mem: Remove the joining of neighbouring ranges
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=cfdaf53104625a04d504972c76545bf869c6a476;p=gem5.git

mem: Remove the joining of neighbouring ranges

This patch temporarily removes the joining of ranges when creating the
backing store, to reserve this functionality for the interleaved
ranges that are about to be introduced.

When creating the mmaps for the backing store, there is no point in
creating larger contigous chunks that what is necessary. The larger
chunks will only make life more difficult for the host.

Merging will be re-added later, but then only for interleaved ranges.
---

diff --git a/src/mem/physical.cc b/src/mem/physical.cc
index e38a4f76e..b6f4c7a95 100644
--- a/src/mem/physical.cc
+++ b/src/mem/physical.cc
@@ -95,59 +95,24 @@ PhysicalMemory::PhysicalMemory(const string& _name,
         }
     }
 
-    // iterate over the increasing addresses and create as large
-    // chunks as possible of contigous space to be mapped to backing
-    // store, also remember what memories constitute the range so we
-    // can go and find out if we have to init their parts to zero
-    AddrRange curr_range;
+    // iterate over the increasing addresses and chunks of contigous
+    // space to be mapped to backing store, also remember what
+    // memories constitute the range so we can go and find out if we
+    // have to init their parts to zero
     vector<AbstractMemory*> curr_memories;
     for (AddrRangeMap<AbstractMemory*>::const_iterator r = addrMap.begin();
          r != addrMap.end(); ++r) {
         // simply skip past all memories that are null and hence do
         // not need any backing store
         if (!r->second->isNull()) {
-            // if the current range is valid, decide if we split or
-            // not
-            if (curr_range.valid()) {
-                // if the ranges are neighbours, then append, this
-                // will eventually be extended to include support for
-                // address striping and merge the interleaved ranges
-                if (curr_range.end + 1 == r->first.start) {
-                    DPRINTF(BusAddrRanges,
-                            "Merging neighbouring ranges %x:%x and %x:%x\n",
-                            curr_range.start, curr_range.end, r->first.start,
-                            r->first.end);
-                    // update the end of the range and add the current
-                    // memory to the list of memories
-                    curr_range.end = r->first.end;
-                    curr_memories.push_back(r->second);
-                } else {
-                    // what we already have is valid, and this is not
-                    // contigious, so create the backing store and
-                    // then start over
-                    createBackingStore(curr_range, curr_memories);
-
-                    // remember the current range and reset the current
-                    // set of memories to contain this one
-                    curr_range = r->first;
-                    curr_memories.clear();
-                    curr_memories.push_back(r->second);
-                }
-            } else {
-                // we haven't seen any valid ranges yet, so remember
-                // the current range and reset the current set of
-                // memories to contain this one
-                curr_range = r->first;
-                curr_memories.clear();
-                curr_memories.push_back(r->second);
-            }
+            // this will eventually be extended to support merging of
+            // interleaved address ranges, and although it might seem
+            // overly complicated at this point it will all be used
+            curr_memories.push_back(r->second);
+            createBackingStore(r->first, curr_memories);
+            curr_memories.clear();
         }
     }
-
-    // if we have a valid range upon finishing the iteration, then
-    // create the backing store
-    if (curr_range.valid())
-        createBackingStore(curr_range, curr_memories);
 }
 
 void
@@ -172,6 +137,10 @@ PhysicalMemory::createBackingStore(AddrRange range,
     // it appropriately
     backingStore.push_back(make_pair(range, pmem));
 
+    // count how many of the memories are to be zero initialized so we
+    // can see if some but not all have this parameter set
+    uint32_t init_to_zero = 0;
+
     // point the memories to their backing store, and if requested,
     // initialize the memory range to 0
     for (vector<AbstractMemory*>::const_iterator m = _memories.begin();
@@ -181,11 +150,17 @@ PhysicalMemory::createBackingStore(AddrRange range,
         (*m)->setBackingStore(pmem);
 
         // if it should be zero, then go and make it so
-        if ((*m)->initToZero())
-            memset(pmem, 0, (*m)->size());
+        if ((*m)->initToZero()) {
+            ++init_to_zero;
+        }
+    }
+
+    if (init_to_zero != 0) {
+        if (init_to_zero != _memories.size())
+            fatal("Some, but not all memories in range %x:%x are set zero\n",
+                  range.start, range.end);
 
-        // advance the pointer for the next memory in line
-        pmem += (*m)->size();
+        memset(pmem, 0, range.size());
     }
 }