src/sim/system.cc - public/gem5 - Git at Google

 /*
  * Copyright (c) 2011-2014,2017-2019 ARM Limited
  * All rights reserved
  *
  * The license below extends only to copyright in the software and shall
  * not be construed as granting a license to any other intellectual
  * property including but not limited to intellectual property relating
  * to a hardware implementation of the functionality of the software
  * licensed hereunder.  You may use the software subject to the license
  * terms below provided that you ensure that this notice is replicated
  * unmodified and in its entirety in all distributions of the software,
  * modified or unmodified, in source code or in binary form.
  *
  * Copyright (c) 2003-2006 The Regents of The University of Michigan
  * Copyright (c) 2011 Regents of the University of California
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met: redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer;
  * redistributions in binary form must reproduce the above copyright
  * notice, this list of conditions and the following disclaimer in the
  * documentation and/or other materials provided with the distribution;
  * neither the name of the copyright holders nor the names of its
  * contributors may be used to endorse or promote products derived from
  * this software without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */

 #include "sim/system.hh"

 #include <algorithm>

 #include "base/compiler.hh"
 #include "base/cprintf.hh"
 #include "base/loader/object_file.hh"
 #include "base/loader/symtab.hh"
 #include "base/str.hh"
 #include "base/trace.hh"
 #include "config/the_isa.hh"
 #if !IS_NULL_ISA
 #include "cpu/base.hh"
 #endif
 #include "cpu/thread_context.hh"
 #include "debug/Loader.hh"
 #include "debug/Quiesce.hh"
 #include "debug/WorkItems.hh"
 #include "mem/abstract_mem.hh"
 #include "mem/physical.hh"
 #include "params/System.hh"
 #include "sim/byteswap.hh"
 #include "sim/debug.hh"
 #include "sim/redirect_path.hh"
 #include "sim/serialize_handlers.hh"

 namespace gem5
 {

 std::vector<System *> System::systemList;

 void
 System::Threads::Thread::resume()
 {
 #   if !IS_NULL_ISA
     DPRINTFS(Quiesce, context->getCpuPtr(), "activating\n");
     context->activate();
 #   endif
 }

 std::string
 System::Threads::Thread::name() const
 {
     assert(context);
     return csprintf("%s.threads[%d]", context->getSystemPtr()->name(),
             context->contextId());
 }

 void
 System::Threads::Thread::quiesce() const
 {
     context->suspend();
     context->getSystemPtr()->workload->recordQuiesce();
 }

 void
 System::Threads::insert(ThreadContext *tc)
 {
     ContextID id = size();
     tc->setContextId(id);

     auto &t = threads.emplace_back();
     t.context = tc;
     // Look up this thread again on resume, in case the threads vector has
     // been reallocated.
     t.resumeEvent = new EventFunctionWrapper(
             [this, id](){ thread(id).resume(); },
             tc->getSystemPtr()->name());
 }

 void
 System::Threads::replace(ThreadContext *tc, ContextID id)
 {
     auto &t = thread(id);
     panic_if(!t.context, "Can't replace a context which doesn't exist.");
 #   if !IS_NULL_ISA
     if (t.resumeEvent->scheduled()) {
         Tick when = t.resumeEvent->when();
         t.context->getCpuPtr()->deschedule(t.resumeEvent);
         tc->getCpuPtr()->schedule(t.resumeEvent, when);
     }
 #   endif
     t.context = tc;
 }

 ThreadContext *
 System::Threads::findFree()
 {
     for (auto &thread: threads) {
         if (thread.context->status() == ThreadContext::Halted)
             return thread.context;
     }
     return nullptr;
 }

 int
 System::Threads::numRunning() const
 {
     int count = 0;
     for (auto &thread: threads) {
         auto status = thread.context->status();
         if (status != ThreadContext::Halted &&
                 status != ThreadContext::Halting) {
             count++;
         }
     }
     return count;
 }

 void
 System::Threads::quiesce(ContextID id)
 {
     auto &t = thread(id);
 #   if !IS_NULL_ISA
     [[maybe_unused]] BaseCPU *cpu = t.context->getCpuPtr();
     DPRINTFS(Quiesce, cpu, "quiesce()\n");
 #   endif
     t.quiesce();
 }

 void
 System::Threads::quiesceTick(ContextID id, Tick when)
 {
 #   if !IS_NULL_ISA
     auto &t = thread(id);
     BaseCPU *cpu = t.context->getCpuPtr();

     DPRINTFS(Quiesce, cpu, "quiesceTick until %u\n", when);
     t.quiesce();

     cpu->reschedule(t.resumeEvent, when, true);
 #   endif
 }

 int System::numSystemsRunning = 0;

 System::System(const Params &p)
     : SimObject(p), _systemPort("system_port", this),
       multiThread(p.multi_thread),
       init_param(p.init_param),
       physProxy(_systemPort, p.cache_line_size),
       workload(p.workload),
       physmem(name() + ".physmem", p.memories, p.mmap_using_noreserve,
               p.shared_backstore, p.auto_unlink_shared_backstore),
       ShadowRomRanges(p.shadow_rom_ranges.begin(),
                       p.shadow_rom_ranges.end()),
       memoryMode(p.mem_mode),
       _cacheLineSize(p.cache_line_size),
       numWorkIds(p.num_work_ids),
       thermalModel(p.thermal_model),
       _m5opRange(p.m5ops_base ?
                  RangeSize(p.m5ops_base, 0x10000) :
                  AddrRange(1, 0)), // Create an empty range if disabled
       redirectPaths(p.redirect_paths)
 {
     panic_if(!workload, "No workload set for system %s "
             "(could use StubWorkload?).", name());
     workload->setSystem(this);

     // add self to global system list
     systemList.push_back(this);

     // check if the cache line size is a value known to work
     if (_cacheLineSize != 16 && _cacheLineSize != 32 &&
         _cacheLineSize != 64 && _cacheLineSize != 128) {
         warn_once("Cache line size is neither 16, 32, 64 nor 128 bytes.\n");
     }

     // Get the generic system requestor IDs
     [[maybe_unused]] RequestorID tmp_id;
     tmp_id = getRequestorId(this, "writebacks");
     assert(tmp_id == Request::wbRequestorId);
     tmp_id = getRequestorId(this, "functional");
     assert(tmp_id == Request::funcRequestorId);
     tmp_id = getRequestorId(this, "interrupt");
     assert(tmp_id == Request::intRequestorId);

     // increment the number of running systems
     numSystemsRunning++;

     // Set back pointers to the system in all memories
     for (int x = 0; x < params().memories.size(); x++)
         params().memories[x]->system(this);
 }

 System::~System()
 {
     for (uint32_t j = 0; j < numWorkIds; j++)
         delete workItemStats[j];
 }

 Port &
 System::getPort(const std::string &if_name, PortID idx)
 {
     // no need to distinguish at the moment (besides checking)
     return _systemPort;
 }

 void
 System::setMemoryMode(enums::MemoryMode mode)
 {
     assert(drainState() == DrainState::Drained);
     memoryMode = mode;
 }

 void
 System::registerThreadContext(ThreadContext *tc)
 {
     threads.insert(tc);

     workload->registerThreadContext(tc);

     for (auto *e: liveEvents)
         tc->schedule(e);
 }

 bool
 System::schedule(PCEvent *event)
 {
     bool all = true;
     liveEvents.push_back(event);
     for (auto *tc: threads)
         all = tc->schedule(event) && all;
     return all;
 }

 bool
 System::remove(PCEvent *event)
 {
     bool all = true;
     liveEvents.remove(event);
     for (auto *tc: threads)
         all = tc->remove(event) && all;
     return all;
 }

 void
 System::replaceThreadContext(ThreadContext *tc, ContextID context_id)
 {
     auto *otc = threads[context_id];
     threads.replace(tc, context_id);

     workload->replaceThreadContext(tc);

     for (auto *e: liveEvents) {
         otc->remove(e);
         tc->schedule(e);
     }
 }

 Addr
 System::memSize() const
 {
     return physmem.totalSize();
 }

 bool
 System::isMemAddr(Addr addr) const
 {
     return physmem.isMemAddr(addr);
 }

 void
 System::addDeviceMemory(RequestorID requestor_id,
     memory::AbstractMemory *deviceMemory)
 {
     deviceMemMap[requestor_id].push_back(deviceMemory);
 }

 bool
 System::isDeviceMemAddr(const PacketPtr& pkt) const
 {
     if (!deviceMemMap.count(pkt->requestorId())) {
         return false;
     }

     return (getDeviceMemory(pkt) != nullptr);
 }

 memory::AbstractMemory *
 System::getDeviceMemory(const PacketPtr& pkt) const
 {
     const RequestorID& rid = pkt->requestorId();

     panic_if(!deviceMemMap.count(rid),
              "No device memory found for Requestor %d\n", rid);

     for (auto& mem : deviceMemMap.at(rid)) {
         if (pkt->getAddrRange().isSubset(mem->getAddrRange())) {
             return mem;
         }
     }

     return nullptr;
 }

 void
 System::serialize(CheckpointOut &cp) const
 {
     for (auto &t: threads.threads) {
         Tick when = 0;
         if (t.resumeEvent && t.resumeEvent->scheduled())
             when = t.resumeEvent->when();
         ContextID id = t.context->contextId();
         paramOut(cp, csprintf("quiesceEndTick_%d", id), when);
     }

     // also serialize the memories in the system
     physmem.serializeSection(cp, "physmem");
 }


 void
 System::unserialize(CheckpointIn &cp)
 {
     for (auto &t: threads.threads) {
         Tick when = 0;
         ContextID id = t.context->contextId();
         if (!optParamIn(cp, csprintf("quiesceEndTick_%d", id), when) ||
                 !when || !t.resumeEvent) {
             continue;
         }
 #       if !IS_NULL_ISA
         t.context->getCpuPtr()->schedule(t.resumeEvent, when);
 #       endif
     }

     // also unserialize the memories in the system
     physmem.unserializeSection(cp, "physmem");
 }

 void
 System::regStats()
 {
     SimObject::regStats();

     for (uint32_t j = 0; j < numWorkIds ; j++) {
         workItemStats[j] = new statistics::Histogram(this);
         std::stringstream namestr;
         ccprintf(namestr, "work_item_type%d", j);
         workItemStats[j]->init(20)
                          .name(namestr.str())
                          .desc("Run time stat for" + namestr.str())
                          .prereq(*workItemStats[j]);
     }
 }

 void
 System::workItemEnd(uint32_t tid, uint32_t workid)
 {
     std::pair<uint32_t,uint32_t> p(tid, workid);
     if (!lastWorkItemStarted.count(p))
         return;

     Tick samp = curTick() - lastWorkItemStarted[p];
     DPRINTF(WorkItems, "Work item end: %d\t%d\t%lld\n", tid, workid, samp);

     if (workid >= numWorkIds)
         fatal("Got workid greater than specified in system configuration\n");

     workItemStats[workid]->sample(samp);
     lastWorkItemStarted.erase(p);
 }

 bool
 System::trapToGdb(int signal, ContextID ctx_id) const
 {
     return workload->trapToGdb(signal, ctx_id);
 }

 void
 System::printSystems()
 {
     std::ios::fmtflags flags(std::cerr.flags());

     std::vector<System *>::iterator i = systemList.begin();
     std::vector<System *>::iterator end = systemList.end();
     for (; i != end; ++i) {
         System *sys = *i;
         std::cerr << "System " << sys->name() << ": " << std::hex << sys
                   << std::endl;
     }

     std::cerr.flags(flags);
 }

 void
 printSystems()
 {
     System::printSystems();
 }

 std::string
 System::stripSystemName(const std::string& requestor_name) const
 {
     if (startswith(requestor_name, name())) {
         return requestor_name.substr(name().size() + 1);
     } else {
         return requestor_name;
     }
 }

 RequestorID
 System::lookupRequestorId(const SimObject* obj) const
 {
     RequestorID id = Request::invldRequestorId;

     // number of occurrences of the SimObject pointer
     // in the requestor list.
     auto obj_number = 0;

     for (int i = 0; i < requestors.size(); i++) {
         if (requestors[i].obj == obj) {
             id = i;
             obj_number++;
         }
     }

     fatal_if(obj_number > 1,
         "Cannot lookup RequestorID by SimObject pointer: "
         "More than one requestor is sharing the same SimObject\n");

     return id;
 }

 RequestorID
 System::lookupRequestorId(const std::string& requestor_name) const
 {
     std::string name = stripSystemName(requestor_name);

     for (int i = 0; i < requestors.size(); i++) {
         if (requestors[i].req_name == name) {
             return i;
         }
     }

     return Request::invldRequestorId;
 }

 RequestorID
 System::getGlobalRequestorId(const std::string& requestor_name)
 {
     return _getRequestorId(nullptr, requestor_name);
 }

 RequestorID
 System::getRequestorId(const SimObject* requestor, std::string subrequestor)
 {
     auto requestor_name = leafRequestorName(requestor, subrequestor);
     return _getRequestorId(requestor, requestor_name);
 }

 RequestorID
 System::_getRequestorId(const SimObject* requestor,
                      const std::string& requestor_name)
 {
     std::string name = stripSystemName(requestor_name);

     // CPUs in switch_cpus ask for ids again after switching
     for (int i = 0; i < requestors.size(); i++) {
         if (requestors[i].req_name == name) {
             return i;
         }
     }

     // Verify that the statistics haven't been enabled yet
     // Otherwise objects will have sized their stat buckets and
     // they will be too small

     if (statistics::enabled()) {
         fatal("Can't request a requestorId after regStats(). "
                 "You must do so in init().\n");
     }

     // Generate a new RequestorID incrementally
     RequestorID requestor_id = requestors.size();

     // Append the new Requestor metadata to the group of system Requestors.
     requestors.emplace_back(requestor, name, requestor_id);

     return requestors.back().id;
 }

 std::string
 System::leafRequestorName(const SimObject* requestor,
                        const std::string& subrequestor)
 {
     if (subrequestor.empty()) {
         return requestor->name();
     } else {
         // Get the full requestor name by appending the subrequestor name to
         // the root SimObject requestor name
         return requestor->name() + "." + subrequestor;
     }
 }

 std::string
 System::getRequestorName(RequestorID requestor_id)
 {
     if (requestor_id >= requestors.size())
         fatal("Invalid requestor_id passed to getRequestorName()\n");

     const auto& requestor_info = requestors[requestor_id];
     return requestor_info.req_name;
 }

 } // namespace gem5
	/*
	* Copyright (c) 2011-2014,2017-2019 ARM Limited
	* All rights reserved
	*
	* The license below extends only to copyright in the software and shall
	* not be construed as granting a license to any other intellectual
	* property including but not limited to intellectual property relating
	* to a hardware implementation of the functionality of the software
	* licensed hereunder. You may use the software subject to the license
	* terms below provided that you ensure that this notice is replicated
	* unmodified and in its entirety in all distributions of the software,
	* modified or unmodified, in source code or in binary form.
	*
	* Copyright (c) 2003-2006 The Regents of The University of Michigan
	* Copyright (c) 2011 Regents of the University of California
	* All rights reserved.
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that the following conditions are
	* met: redistributions of source code must retain the above copyright
	* notice, this list of conditions and the following disclaimer;
	* redistributions in binary form must reproduce the above copyright
	* notice, this list of conditions and the following disclaimer in the
	* documentation and/or other materials provided with the distribution;
	* neither the name of the copyright holders nor the names of its
	* contributors may be used to endorse or promote products derived from
	* this software without specific prior written permission.
	*
	* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
	* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
	* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
	* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
	* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
	* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
	* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
	* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	*/

	#include "sim/system.hh"

	#include <algorithm>

	#include "base/compiler.hh"
	#include "base/cprintf.hh"
	#include "base/loader/object_file.hh"
	#include "base/loader/symtab.hh"
	#include "base/str.hh"
	#include "base/trace.hh"
	#include "config/the_isa.hh"
	#if !IS_NULL_ISA
	#include "cpu/base.hh"
	#endif
	#include "cpu/thread_context.hh"
	#include "debug/Loader.hh"
	#include "debug/Quiesce.hh"
	#include "debug/WorkItems.hh"
	#include "mem/abstract_mem.hh"
	#include "mem/physical.hh"
	#include "params/System.hh"
	#include "sim/byteswap.hh"
	#include "sim/debug.hh"
	#include "sim/redirect_path.hh"
	#include "sim/serialize_handlers.hh"

	namespace gem5
	{

	std::vector<System *> System::systemList;

	void
	System::Threads::Thread::resume()
	{
	# if !IS_NULL_ISA
	DPRINTFS(Quiesce, context->getCpuPtr(), "activating\n");
	context->activate();
	# endif
	}

	std::string
	System::Threads::Thread::name() const
	{
	assert(context);
	return csprintf("%s.threads[%d]", context->getSystemPtr()->name(),
	context->contextId());
	}

	void
	System::Threads::Thread::quiesce() const
	{
	context->suspend();
	context->getSystemPtr()->workload->recordQuiesce();
	}

	void
	System::Threads::insert(ThreadContext *tc)
	{
	ContextID id = size();
	tc->setContextId(id);

	auto &t = threads.emplace_back();
	t.context = tc;
	// Look up this thread again on resume, in case the threads vector has
	// been reallocated.
	t.resumeEvent = new EventFunctionWrapper(
	[this, id](){ thread(id).resume(); },
	tc->getSystemPtr()->name());
	}

	void
	System::Threads::replace(ThreadContext *tc, ContextID id)
	{
	auto &t = thread(id);
	panic_if(!t.context, "Can't replace a context which doesn't exist.");
	# if !IS_NULL_ISA
	if (t.resumeEvent->scheduled()) {
	Tick when = t.resumeEvent->when();
	t.context->getCpuPtr()->deschedule(t.resumeEvent);
	tc->getCpuPtr()->schedule(t.resumeEvent, when);
	}
	# endif
	t.context = tc;
	}

	ThreadContext *
	System::Threads::findFree()
	{
	for (auto &thread: threads) {
	if (thread.context->status() == ThreadContext::Halted)
	return thread.context;
	}
	return nullptr;
	}

	int
	System::Threads::numRunning() const
	{
	int count = 0;
	for (auto &thread: threads) {
	auto status = thread.context->status();
	if (status != ThreadContext::Halted &&
	status != ThreadContext::Halting) {
	count++;
	}
	}
	return count;
	}

	void
	System::Threads::quiesce(ContextID id)
	{
	auto &t = thread(id);
	# if !IS_NULL_ISA
	[[maybe_unused]] BaseCPU *cpu = t.context->getCpuPtr();
	DPRINTFS(Quiesce, cpu, "quiesce()\n");
	# endif
	t.quiesce();
	}

	void
	System::Threads::quiesceTick(ContextID id, Tick when)
	{
	# if !IS_NULL_ISA
	auto &t = thread(id);
	BaseCPU *cpu = t.context->getCpuPtr();

	DPRINTFS(Quiesce, cpu, "quiesceTick until %u\n", when);
	t.quiesce();

	cpu->reschedule(t.resumeEvent, when, true);
	# endif
	}

	int System::numSystemsRunning = 0;

	System::System(const Params &p)
	: SimObject(p), _systemPort("system_port", this),
	multiThread(p.multi_thread),
	init_param(p.init_param),
	physProxy(_systemPort, p.cache_line_size),
	workload(p.workload),
	physmem(name() + ".physmem", p.memories, p.mmap_using_noreserve,
	p.shared_backstore, p.auto_unlink_shared_backstore),
	ShadowRomRanges(p.shadow_rom_ranges.begin(),
	p.shadow_rom_ranges.end()),
	memoryMode(p.mem_mode),
	_cacheLineSize(p.cache_line_size),
	numWorkIds(p.num_work_ids),
	thermalModel(p.thermal_model),
	_m5opRange(p.m5ops_base ?
	RangeSize(p.m5ops_base, 0x10000) :
	AddrRange(1, 0)), // Create an empty range if disabled
	redirectPaths(p.redirect_paths)
	{
	panic_if(!workload, "No workload set for system %s "
	"(could use StubWorkload?).", name());
	workload->setSystem(this);

	// add self to global system list
	systemList.push_back(this);

	// check if the cache line size is a value known to work
	if (_cacheLineSize != 16 && _cacheLineSize != 32 &&
	_cacheLineSize != 64 && _cacheLineSize != 128) {
	warn_once("Cache line size is neither 16, 32, 64 nor 128 bytes.\n");
	}

	// Get the generic system requestor IDs
	[[maybe_unused]] RequestorID tmp_id;
	tmp_id = getRequestorId(this, "writebacks");
	assert(tmp_id == Request::wbRequestorId);
	tmp_id = getRequestorId(this, "functional");
	assert(tmp_id == Request::funcRequestorId);
	tmp_id = getRequestorId(this, "interrupt");
	assert(tmp_id == Request::intRequestorId);

	// increment the number of running systems
	numSystemsRunning++;

	// Set back pointers to the system in all memories
	for (int x = 0; x < params().memories.size(); x++)
	params().memories[x]->system(this);
	}

	System::~System()
	{
	for (uint32_t j = 0; j < numWorkIds; j++)
	delete workItemStats[j];
	}

	Port &
	System::getPort(const std::string &if_name, PortID idx)
	{
	// no need to distinguish at the moment (besides checking)
	return _systemPort;
	}

	void
	System::setMemoryMode(enums::MemoryMode mode)
	{
	assert(drainState() == DrainState::Drained);
	memoryMode = mode;
	}

	void
	System::registerThreadContext(ThreadContext *tc)
	{
	threads.insert(tc);

	workload->registerThreadContext(tc);

	for (auto *e: liveEvents)
	tc->schedule(e);
	}

	bool
	System::schedule(PCEvent *event)
	{
	bool all = true;
	liveEvents.push_back(event);
	for (auto *tc: threads)
	all = tc->schedule(event) && all;
	return all;
	}

	bool
	System::remove(PCEvent *event)
	{
	bool all = true;
	liveEvents.remove(event);
	for (auto *tc: threads)
	all = tc->remove(event) && all;
	return all;
	}

	void
	System::replaceThreadContext(ThreadContext *tc, ContextID context_id)
	{
	auto *otc = threads[context_id];
	threads.replace(tc, context_id);

	workload->replaceThreadContext(tc);

	for (auto *e: liveEvents) {
	otc->remove(e);
	tc->schedule(e);
	}
	}

	Addr
	System::memSize() const
	{
	return physmem.totalSize();
	}

	bool
	System::isMemAddr(Addr addr) const
	{
	return physmem.isMemAddr(addr);
	}

	void
	System::addDeviceMemory(RequestorID requestor_id,
	memory::AbstractMemory *deviceMemory)
	{
	deviceMemMap[requestor_id].push_back(deviceMemory);
	}

	bool
	System::isDeviceMemAddr(const PacketPtr& pkt) const
	{
	if (!deviceMemMap.count(pkt->requestorId())) {
	return false;
	}

	return (getDeviceMemory(pkt) != nullptr);
	}

	memory::AbstractMemory *
	System::getDeviceMemory(const PacketPtr& pkt) const
	{
	const RequestorID& rid = pkt->requestorId();

	panic_if(!deviceMemMap.count(rid),
	"No device memory found for Requestor %d\n", rid);

	for (auto& mem : deviceMemMap.at(rid)) {
	if (pkt->getAddrRange().isSubset(mem->getAddrRange())) {
	return mem;
	}
	}

	return nullptr;
	}

	void
	System::serialize(CheckpointOut &cp) const
	{
	for (auto &t: threads.threads) {
	Tick when = 0;
	if (t.resumeEvent && t.resumeEvent->scheduled())
	when = t.resumeEvent->when();
	ContextID id = t.context->contextId();
	paramOut(cp, csprintf("quiesceEndTick_%d", id), when);
	}

	// also serialize the memories in the system
	physmem.serializeSection(cp, "physmem");
	}


	void
	System::unserialize(CheckpointIn &cp)
	{
	for (auto &t: threads.threads) {
	Tick when = 0;
	ContextID id = t.context->contextId();
	if (!optParamIn(cp, csprintf("quiesceEndTick_%d", id), when) \|\|
	!when \|\| !t.resumeEvent) {
	continue;
	}
	# if !IS_NULL_ISA
	t.context->getCpuPtr()->schedule(t.resumeEvent, when);
	# endif
	}

	// also unserialize the memories in the system
	physmem.unserializeSection(cp, "physmem");
	}

	void
	System::regStats()
	{
	SimObject::regStats();

	for (uint32_t j = 0; j < numWorkIds ; j++) {
	workItemStats[j] = new statistics::Histogram(this);
	std::stringstream namestr;
	ccprintf(namestr, "work_item_type%d", j);
	workItemStats[j]->init(20)
	.name(namestr.str())
	.desc("Run time stat for" + namestr.str())
	.prereq(*workItemStats[j]);
	}
	}

	void
	System::workItemEnd(uint32_t tid, uint32_t workid)
	{
	std::pair<uint32_t,uint32_t> p(tid, workid);
	if (!lastWorkItemStarted.count(p))
	return;

	Tick samp = curTick() - lastWorkItemStarted[p];
	DPRINTF(WorkItems, "Work item end: %d\t%d\t%lld\n", tid, workid, samp);

	if (workid >= numWorkIds)
	fatal("Got workid greater than specified in system configuration\n");

	workItemStats[workid]->sample(samp);
	lastWorkItemStarted.erase(p);
	}

	bool
	System::trapToGdb(int signal, ContextID ctx_id) const
	{
	return workload->trapToGdb(signal, ctx_id);
	}

	void
	System::printSystems()
	{
	std::ios::fmtflags flags(std::cerr.flags());

	std::vector<System *>::iterator i = systemList.begin();
	std::vector<System *>::iterator end = systemList.end();
	for (; i != end; ++i) {
	System sys = i;
	std::cerr << "System " << sys->name() << ": " << std::hex << sys
	<< std::endl;
	}

	std::cerr.flags(flags);
	}

	void
	printSystems()
	{
	System::printSystems();
	}

	std::string
	System::stripSystemName(const std::string& requestor_name) const
	{
	if (startswith(requestor_name, name())) {
	return requestor_name.substr(name().size() + 1);
	} else {
	return requestor_name;
	}
	}

	RequestorID
	System::lookupRequestorId(const SimObject* obj) const
	{
	RequestorID id = Request::invldRequestorId;

	// number of occurrences of the SimObject pointer
	// in the requestor list.
	auto obj_number = 0;

	for (int i = 0; i < requestors.size(); i++) {
	if (requestors[i].obj == obj) {
	id = i;
	obj_number++;
	}
	}

	fatal_if(obj_number > 1,
	"Cannot lookup RequestorID by SimObject pointer: "
	"More than one requestor is sharing the same SimObject\n");

	return id;
	}

	RequestorID
	System::lookupRequestorId(const std::string& requestor_name) const
	{
	std::string name = stripSystemName(requestor_name);

	for (int i = 0; i < requestors.size(); i++) {
	if (requestors[i].req_name == name) {
	return i;
	}
	}

	return Request::invldRequestorId;
	}

	RequestorID
	System::getGlobalRequestorId(const std::string& requestor_name)
	{
	return _getRequestorId(nullptr, requestor_name);
	}

	RequestorID
	System::getRequestorId(const SimObject* requestor, std::string subrequestor)
	{
	auto requestor_name = leafRequestorName(requestor, subrequestor);
	return _getRequestorId(requestor, requestor_name);
	}

	RequestorID
	System::_getRequestorId(const SimObject* requestor,
	const std::string& requestor_name)
	{
	std::string name = stripSystemName(requestor_name);

	// CPUs in switch_cpus ask for ids again after switching
	for (int i = 0; i < requestors.size(); i++) {
	if (requestors[i].req_name == name) {
	return i;
	}
	}

	// Verify that the statistics haven't been enabled yet
	// Otherwise objects will have sized their stat buckets and
	// they will be too small

	if (statistics::enabled()) {
	fatal("Can't request a requestorId after regStats(). "
	"You must do so in init().\n");
	}

	// Generate a new RequestorID incrementally
	RequestorID requestor_id = requestors.size();

	// Append the new Requestor metadata to the group of system Requestors.
	requestors.emplace_back(requestor, name, requestor_id);

	return requestors.back().id;
	}

	std::string
	System::leafRequestorName(const SimObject* requestor,
	const std::string& subrequestor)
	{
	if (subrequestor.empty()) {
	return requestor->name();
	} else {
	// Get the full requestor name by appending the subrequestor name to
	// the root SimObject requestor name
	return requestor->name() + "." + subrequestor;
	}
	}

	std::string
	System::getRequestorName(RequestorID requestor_id)
	{
	if (requestor_id >= requestors.size())
	fatal("Invalid requestor_id passed to getRequestorName()\n");

	const auto& requestor_info = requestors[requestor_id];
	return requestor_info.req_name;
	}

	} // namespace gem5