#include "mem/abstract_mem.hh"
#include "mem/physical.hh"
+/**
+ * On Linux, MAP_NORESERVE allow us to simulate a very large memory
+ * without committing to actually providing the swap space on the
+ * host. On OSX the MAP_NORESERVE flag does not exist, so simply make
+ * it 0.
+ */
+#if defined(__APPLE__)
+#ifndef MAP_NORESERVE
+#define MAP_NORESERVE 0
+#endif
+#endif
+
using namespace std;
PhysicalMemory::PhysicalMemory(const string& _name,
- const vector<AbstractMemory*>& _memories) :
- _name(_name), rangeCache(addrMap.end()), size(0)
+ const vector<AbstractMemory*>& _memories,
+ bool mmap_using_noreserve) :
+ _name(_name), rangeCache(addrMap.end()), size(0),
+ mmapUsingNoReserve(mmap_using_noreserve)
{
+ if (mmap_using_noreserve)
+ warn("Not reserving swap space. May cause SIGSEGV on actual usage\n");
+
// add the memories from the system to the address map as
// appropriate
for (const auto& m : _memories) {
DPRINTF(AddrRanges, "Creating backing store for range %s with size %d\n",
range.to_string(), range.size());
int map_flags = MAP_ANON | MAP_PRIVATE;
+
+ // to be able to simulate very large memories, the user can opt to
+ // pass noreserve to mmap
+ if (mmapUsingNoReserve) {
+ map_flags |= MAP_NORESERVE;
+ }
+
uint8_t* pmem = (uint8_t*) mmap(NULL, range.size(),
PROT_READ | PROT_WRITE,
map_flags, -1, 0);
// The total memory size
uint64_t size;
+ // Let the user choose if we reserve swap space when calling mmap
+ const bool mmapUsingNoReserve;
+
// The physical memory used to provide the memory in the simulated
// system
std::vector<std::pair<AddrRange, uint8_t*>> backingStore;
* Create a physical memory object, wrapping a number of memories.
*/
PhysicalMemory(const std::string& _name,
- const std::vector<AbstractMemory*>& _memories);
+ const std::vector<AbstractMemory*>& _memories,
+ bool mmap_using_noreserve);
/**
* Unmap all the backing store we have used.
"All memories in the system")
mem_mode = Param.MemoryMode('atomic', "The mode the memory system is in")
+ # When reserving memory on the host, we have the option of
+ # reserving swap space or not (by passing MAP_NORESERVE to
+ # mmap). By enabling this flag, we accomodate cases where a large
+ # (but sparse) memory is simulated.
+ mmap_using_noreserve = Param.Bool(False, "mmap the backing store " \
+ "without reserving swap")
+
# The memory ranges are to be populated when creating the system
# such that these can be passed from the I/O subsystem through an
# I/O bridge or cache
loadAddrMask(p->load_addr_mask),
loadAddrOffset(p->load_offset),
nextPID(0),
- physmem(name() + ".physmem", p->memories),
+ physmem(name() + ".physmem", p->memories, p->mmap_using_noreserve),
memoryMode(p->mem_mode),
_cacheLineSize(p->cache_line_size),
workItemsBegin(0),