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authorAli Saidi <ali.saidi@arm.com>2014-03-07 15:56:23 -0500
committerAli Saidi <ali.saidi@arm.com>2014-03-07 15:56:23 -0500
commitbf39a475fe8c796e5b0f5b37ee2e4aca724d05f3 (patch)
treea0a877c2ef712e0b1341834f887ee3320542f8cf
parentf4a897d8e3e7a9fe5f409c0f15dfa5ba9438776c (diff)
downloadgem5-bf39a475fe8c796e5b0f5b37ee2e4aca724d05f3.tar.xz
mem: Wakeup sleeping CPUs without caches on LLSC
For systems without caches, the LLSC code does not get snoops for wake-ups. We add the LLSC code in the abstract memory to do the job for us.
-rw-r--r--src/arch/null/cpu_dummy.hh1
-rw-r--r--src/mem/abstract_mem.cc8
2 files changed, 9 insertions, 0 deletions
diff --git a/src/arch/null/cpu_dummy.hh b/src/arch/null/cpu_dummy.hh
index ed6f6d1d6..f546b4141 100644
--- a/src/arch/null/cpu_dummy.hh
+++ b/src/arch/null/cpu_dummy.hh
@@ -47,6 +47,7 @@ class BaseCPU
public:
static int numSimulatedInsts() { return 0; }
static int numSimulatedOps() { return 0; }
+ static void wakeup() { ; }
};
#endif // __ARCH_NULL_CPU_DUMMY_HH__
diff --git a/src/mem/abstract_mem.cc b/src/mem/abstract_mem.cc
index a169243e9..98f03b9af 100644
--- a/src/mem/abstract_mem.cc
+++ b/src/mem/abstract_mem.cc
@@ -44,6 +44,8 @@
#include "arch/registers.hh"
#include "config/the_isa.hh"
+#include "cpu/base.hh"
+#include "cpu/thread_context.hh"
#include "debug/LLSC.hh"
#include "debug/MemoryAccess.hh"
#include "mem/abstract_mem.hh"
@@ -260,6 +262,12 @@ AbstractMemory::checkLockedAddrList(PacketPtr pkt)
if (i->addr == paddr) {
DPRINTF(LLSC, "Erasing lock record: context %d addr %#x\n",
i->contextId, paddr);
+ // For ARM, a spinlock would typically include a Wait
+ // For Event (WFE) to conserve energy. The ARMv8
+ // architecture specifies that an event is
+ // automatically generated when clearing the exclusive
+ // monitor to wake up the processor in WFE.
+ system()->getThreadContext(i->contextId)->getCpuPtr()->wakeup();
i = lockedAddrList.erase(i);
} else {
i++;