sim: Add a system-global option to bypass caches

Virtualized CPUs and the fastmem mode of the atomic CPU require direct
access to physical memory. We currently require caches to be disabled
when using them to prevent chaos. This is not ideal when switching
between hardware virutalized CPUs and other CPU models as it would
require a configuration change on each switch. This changeset
introduces a new version of the atomic memory mode,
'atomic_noncaching', where memory accesses are inserted into the
memory system as atomic accesses, but bypass caches.

To make memory mode tests cleaner, the following methods are added to
the System class:

 * isAtomicMode() -- True if the memory mode is 'atomic' or 'direct'.
 * isTimingMode() -- True if the memory mode is 'timing'.
 * bypassCaches() -- True if caches should be bypassed.

The old getMemoryMode() and setMemoryMode() methods should never be
used from the C++ world anymore.

3 files changed, 3 insertions, 3 deletions

diff --git a/src/arch/arm/table_walker.cc b/src/arch/arm/table_walker.cc
index 99a7592c1..44f12833b 100644
--- a/src/arch/arm/table_walker.cc
+++ b/src/arch/arm/table_walker.cc
@@ -104,7 +104,7 @@ void
 TableWalker::drainResume()
 {
     Drainable::drainResume();
-    if ((params()->sys->getMemoryMode() == Enums::timing) && currState) {
+    if (params()->sys->isTimingMode() && currState) {
         delete currState;
         currState = NULL;
     }
diff --git a/src/arch/x86/interrupts.cc b/src/arch/x86/interrupts.cc
index b34124ce7..8eae2d390 100644
--- a/src/arch/x86/interrupts.cc
+++ b/src/arch/x86/interrupts.cc
@@ -510,7 +510,7 @@ X86ISA::Interrupts::setReg(ApicRegIndex reg, uint32_t val)
             message.destMode = low.destMode;
             message.level = low.level;
             message.trigger = low.trigger;
-            bool timing = sys->getMemoryMode() == Enums::timing;
+            bool timing(sys->isTimingMode());
             // Be careful no updates of the delivery status bit get lost.
             regs[APIC_INTERRUPT_COMMAND_LOW] = low;
             ApicList apics;
diff --git a/src/arch/x86/pagetable_walker.cc b/src/arch/x86/pagetable_walker.cc
index 1e42e5593..b096fbfe8 100644
--- a/src/arch/x86/pagetable_walker.cc
+++ b/src/arch/x86/pagetable_walker.cc
@@ -88,7 +88,7 @@ Walker::start(ThreadContext * _tc, BaseTLB::Translation *_translation,
     // outstanding requests, see if this request can be coalesced with
     // another one (i.e. either coalesce or start walk)
     WalkerState * newState = new WalkerState(this, _translation, _req);
-    newState->initState(_tc, _mode, sys->getMemoryMode() == Enums::timing);
+    newState->initState(_tc, _mode, sys->isTimingMode());
     if (currStates.size()) {
         assert(newState->isTiming());
         DPRINTF(PageTableWalker, "Walks in progress: %d\n", currStates.size());