diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 74bdd2c..590c773 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -86,20 +86,20 @@
  git clone https://gem5.googlesource.com/public/gem5
 ```
 
-By default, the master branch is checked out. The master branch is stable,
-containing the latest released version of gem5. To obtain code still
-under-development (and which contributions can be made):
+By default, the stable branch is checked out. The stable branch contains the
+latest released version of gem5. To obtain code still under-development (and
+which contributions can be made):
 
 ```
 cd gem5
 git checkout --track origin/develop
 ```
 
-Changes should be made to this develop branch. Changes to the master branch
+Changes should be made to this develop branch. Changes to the stable branch
 will be blocked. Once a change on the develop branch is properly incorporated
-into the gem5 repo it will be merged into the master Branch upon the next
+into the gem5 repo it will be merged into the stable Branch upon the next
 release of gem5. New releases of gem5 occur three times a year. Ergo, changes
-made to the develop branch should appear on the master branch within three to
+made to the develop branch should appear on the stable branch within three to
 four months as part of a stable release.
 
 Other gem5 repositories
@@ -322,7 +322,7 @@
 ========
 
 By default, contributions to gem5 should be made on the develop branch. The
-master branch is maintained as a stable release branch (i.e., it can be pulled
+stable branch is maintained as a stable release branch (i.e., it can be pulled
 to obtain the latest official release of gem5). Creation of additional branches
 is generally discouraged due to their tendency to bloat git repositories with
 abandoned code. However, the creation of new branches is permitted for
@@ -491,7 +491,7 @@
 2. When a release is ready, a new staging branch shall be created by a project
 maintainer, from develop, with the name "release-staging-{VERSION}". The
 gem5-dev mailing list will be notified that the staging branch will be merged
-into the master branch after two weeks, thus marking the new release.
+into the stable branch after two weeks, thus marking the new release.
 3. The staging branch will have the full suite of gem5 tests run on it to
 ensure all tests pass and the to-be-released code is in a decent state.
 4. If a user submits a changeset to the staging branch, it will be considered
@@ -504,8 +504,8 @@
 to gem5 will continue to be made to the develop branch. Patches submitted
 into the staging branch do not need to be re-added to the develop branch.
 5. Once signed off by members of the PMC the staging branch shall be merged
-into the master and develop branch. The staging branch will then be deleted.
-6. The master branch shall be tagged with the correct version number for that
+into the stable and develop branch. The staging branch will then be deleted.
+6. The stable branch shall be tagged with the correct version number for that
 release. gem5 conforms to a "v{YY}.{MAJOR}.{MINOR}.{HOTFIX}" versioning system.
 E.g., the first major release of 2022 will be "v22.0.0.0", followed by
 "v22.1.0.0". All the releases (with the exception of hotfixes) are considered
@@ -527,14 +527,14 @@
 made by members of the PMC if there is no consensus. Assuming the hotfix is
 permitted, the following steps will be taken:
 
-1. A new branch with the prefix "hotfix-" will be created from the master
+1. A new branch with the prefix "hotfix-" will be created from the stable
 branch. Only gem5 maintainers can create branches. If a non-maintainer requires
 the creation of a hotfix branch then they should contact a gem5 maintainer.
 2. The change shall be submitted to the hotfix branch via gerrit. Full review,
 as with any other change, will be required.
 3. Once fully submitted, the hotfix branch shall be merged into both the
-develop and the master branch by a gem5 maintainer.
-4. The master branch will be tagged with the new version number; the same as
+develop and the stable branch by a gem5 maintainer.
+4. The stable branch will be tagged with the new version number; the same as
 the last but with an incremented hotfix number (e.g., "v20.2.0.0" would
 transition to "v20.2.0.1").
 4. The hotfix branch will then be deleted.
diff --git a/RELEASE-NOTES.md b/RELEASE-NOTES.md
index 1a97b4c..492bb96 100644
--- a/RELEASE-NOTES.md
+++ b/RELEASE-NOTES.md
@@ -1,6 +1,124 @@
 # Version 20.1.0.0
 
-* m5.stats.dump() root argument renamed to roots to reflect the fact that it now takes a list of SimObjects
+Thank you to everyone that made this release possible!
+This has been a very productive release with [150 issues](https://gem5.atlassian.net/), over 650  commits (a 25% increase from the 20.0 release), and 58 unique contributors (a 100% increase!).
+
+## Process changes
+
+We are no longer using the "master" branch.
+Instead, we will have two branches:
+
+* "stable": This will point to the latest stable release (gem5-20.1 as of today)
+* "develop": This is the latest development code that will be merged in to the "stable" branch at each release.
+
+We suggest all *users* use the stable (default) branch.
+However, to contribute your fixes and new changes to gem5, it should be contributed to the develop branch.
+See CONTRIBUTING.md for more details.
+
+gem5 has also implemented a project code of conduct.
+See the CODE-OF-CONDUCT.md file for details.
+In the code of conduct "we pledge to act and interact in ways that contribute to an open, welcoming, diverse, inclusive, and healthy community."
+
+## New features in 20.1
+
+### New DRAM interface: Contributed by *Wendy Elsasser*
+
+You can find details about this on the [gem5 blog](http://www.gem5.org/2020/05/27/memory-controller.html) or Wendy's talks on YouTube: [Talk on new interface and NVM](https://www.youtube.com/watch?v=t2PRoZPwwpk) and the [talk on LPDDR5](https://www.youtube.com/watch?v=ttJ9_I_Avyc)
+
+* **[PYTHON API CHANGE]**: The DRAM models are now *DRAM interfaces* which is a child of the *memory controller*. Example change shown [in the blog post](http://www.gem5.org/project/2020/07/18/gem5-20-1.html).
+  * The DRAM is split into a memory controller and a DRAM interface
+  * `SimpleMemory` is no longer a drop-in replacement for a DRAM-based memory controller.
+* LPDDR5 model added
+* NVM model added
+* New memory controller model that can use both NVM and DRAM
+
+### Improved on-chip interconnect model, HeteroGarnet: Contributed by *Srikant Bharadwaj*
+
+You can find details about this on the [gem5 blog](http://www.gem5.org/2020/05/27/heterogarnet.html) and [Srikant's talk on YouTube](https://www.youtube.com/watch?v=AH9r44r2lHA).
+
+* **[USER-FACING CHANGE]**: The network type options are now "simple" and "garnet" instead of "garnet2.0". (If "garnet2.0" is used, you will get a warning until gem5-20.2)
+* Added models for clock domain crossings and serialization/deserialization (SERDES)
+
+### Transactional memory support: Contributed by *Timothy Hayes*
+
+You can find details on the [Jira issue](https://gem5.atlassian.net/browse/GEM5-587)
+
+* gem5 now supports Arm TME (transactional memory extensions)
+* Transactional memory is only implemented in the `MESI_Three_Level_HTM` Ruby protocol, and it is only implemented in Ruby.
+* This implements a checkpointing mechanism for the architectural state and buffering of speculative memory updates.
+* IBM POWER and x86 HTM extensions have *not* been implemented.
+
+### Other new features
+
+* External simulator integrations
+  * Added support for DRAMSim3
+  * Added back support for DRAMSim2
+* Armv8-A Self Hosted Debug extension added
+* KVM support for Armv8-A  hosts without GICv2 hardware
+* Implemented Secure EL2 for Armv8-A
+
+## Removed features
+
+* Dropped support for mercurial version control
+
+## New supported platforms
+
+* GCC up to 10.2 is now supported. Minimum GCC is now 5.0.
+* Clang up to version 9. Minimum Clang is now 3.9.
+
+## Platforms no longer support
+
+* **[USER-FACING CHANGE]**: Python 2 is officially deprecated. We will drop support for Python 2 in the next release. In this release you will get a warning if you're using Python 2.
+* **[USER-FACING CHANGE]**: We have dropped support for GCC 4.X
+* **[USER-FACING CHANGE]**: We have dropped support for Scons 2.x (Note: this is the default in Ubuntu 16.04. Use pip to install a newer scons.)
+
+See <http://www.gem5.org/documentation/general_docs/building> for gem5's current dependencies.
+
+## Other changes
+
+### Deprecating "master" and "slave"
+
+* **[API CHANGE]**: The names "master" and "slave" have been deprecated
+  * Special thanks to Lakin Smith, Shivani Parekh, Eden Avivi, and Emily Brickey.
+  * Below is a guide to most of the name changes.
+  * The goal was to replace problematic language with more descriptive and precise terms.
+* There may be some bugs introduced with this change as there were many places in the Python configurations which relied on "duck typing".
+* This change is mostly backwards compatible and warning will be issued until at least gem5-20.2.
+
+```
+MasterPort -> RequestorPort
+SlavePort -> ResponsePort
+
+xbar.slave -> xbar.cpu_side
+xbar.master -> xbar.mem_side
+
+MasterId -> RequestorId
+```
+
+### Testing improvements
+
+* We now have Jenkins server (<http://jenkins.gem5.org/>) running nightly and other large tests. Special thanks to Mike Upton for setting this up!
+  * Nightly tests run the "long" regression tests (many tests added).
+  * Compiler tests run gem5 build for many targets and all compilers once a week.
+* Updated CI tester (kokoro) to use a more up-to-date environment.
+* Improved the testing infrastructure.
+  * Almost all testing resources now available in [gem5-resources repository](https://gem5.googlesource.com/public/gem5-resources/).
+  * Generally cleaned up the `tests/` directory in mainline gem5.
+  * Many general testlib improvements.
+
+### More changes
+
+* **[PYTHON API CHANGE]**: m5.stats.dump() root argument renamed to roots to reflect the fact that it now takes a list of SimObjects
+* **[USER-FACING CHANGE]**: Checkpoint compatibility may be broken by the following changes
+  * <https://gem5-review.googlesource.com/c/public/gem5/+/25145>
+  * <https://gem5-review.googlesource.com/c/public/gem5/+/31874>
+* **[API CHANGE]** Changed `setCPU` to `setThreadContext` in Interrupts
+* Added a `Compressor` namespace.
+* **[API CHANGE]** The `Callback` class was removed and replaced with C++ lambdas.
+* Many objects' stats have been updated to the "new" stats style.
+* Many more objects have had their APIs formalized. See <http://www.gem5.org/documentation/general_docs/gem5-apis>
+
+----------------------------------------------------------------------------------------------------
 
 # Version 20.0.0.3
 
diff --git a/SConstruct b/SConstruct
index ebb59f6..ce9e9b6 100755
--- a/SConstruct
+++ b/SConstruct
@@ -238,7 +238,8 @@
     ('MARSHAL_CCFLAGS_EXTRA', 'Extra C and C++ marshal compiler flags', ''),
     ('MARSHAL_LDFLAGS_EXTRA', 'Extra marshal linker flags', ''),
     ('PYTHON_CONFIG', 'Python config binary to use',
-     [ 'python2.7-config', 'python-config', 'python3-config' ]),
+     [ 'python3-config', 'python-config', 'python2.7-config', 'python2-config']
+    ),
     ('PROTOC', 'protoc tool', environ.get('PROTOC', 'protoc')),
     ('BATCH', 'Use batch pool for build and tests', False),
     ('BATCH_CMD', 'Batch pool submission command name', 'qdo'),
@@ -336,12 +337,6 @@
     main.Append(PSHLINKFLAGS=shared_partial_flags)
     main.Append(PLINKFLAGS=shared_partial_flags)
 
-    # Treat warnings as errors but white list some warnings that we
-    # want to allow (e.g., deprecation warnings).
-    main.Append(CCFLAGS=['-Werror',
-                         '-Wno-error=deprecated-declarations',
-                         '-Wno-error=deprecated',
-                        ])
 else:
     error('\n'.join((
           "Don't know what compiler options to use for your compiler.",
@@ -636,6 +631,10 @@
               main['PYTHON_CONFIG'])
 
     print("Info: Using Python config: %s" % (python_config, ))
+    if python_config != 'python3-config':
+        warning('python3-config could not be found.\n'
+                'Future releases of gem5 will drop support for python2.')
+
     py_includes = readCommand([python_config, '--includes'],
                               exception='').split()
     py_includes = list(filter(
diff --git a/configs/ruby/Ruby.py b/configs/ruby/Ruby.py
index 622771a..86d5748 100644
--- a/configs/ruby/Ruby.py
+++ b/configs/ruby/Ruby.py
@@ -136,7 +136,7 @@
             mem_ctrl = m5.objects.MemCtrl(dram = dram_intf)
 
             if options.access_backing_store:
-                mem_ctrl.kvm_map=False
+                dram_intf.kvm_map=False
 
             mem_ctrls.append(mem_ctrl)
             dir_ranges.append(mem_ctrl.dram.range)
diff --git a/ext/pybind11/include/pybind11/pybind11.h b/ext/pybind11/include/pybind11/pybind11.h
index a9ee31a..04ef30f 100644
--- a/ext/pybind11/include/pybind11/pybind11.h
+++ b/ext/pybind11/include/pybind11/pybind11.h
@@ -12,6 +12,7 @@
 #ifdef __clang__
 #pragma clang diagnostic push
 #pragma clang diagnostic ignored "-Wunused-value"
+#pragma clang diagnostic warning "-Wrange-loop-analysis"
 #endif
 
 #if defined(__INTEL_COMPILER)
diff --git a/ext/testlib/configuration.py b/ext/testlib/configuration.py
index 1267c25..3203479 100644
--- a/ext/testlib/configuration.py
+++ b/ext/testlib/configuration.py
@@ -214,7 +214,7 @@
                                                       os.pardir,
                                                       os.pardir))
     defaults.result_path = os.path.join(os.getcwd(), 'testing-results')
-    defaults.resource_url = 'http://dist.gem5.org/dist/develop'
+    defaults.resource_url = 'http://dist.gem5.org/dist/v20-1'
     defaults.resource_path = os.path.abspath(os.path.join(defaults.base_dir,
                                             'tests',
                                             'gem5',
diff --git a/src/Doxyfile b/src/Doxyfile
index c92a787..d029a66 100644
--- a/src/Doxyfile
+++ b/src/Doxyfile
@@ -31,7 +31,7 @@
 # This could be handy for archiving the generated documentation or 
 # if some version control system is used.
 
-PROJECT_NUMBER         = DEVELOP-FOR-V20.1
+PROJECT_NUMBER         = v20.1.0.0
 
 # The OUTPUT_DIRECTORY tag is used to specify the (relative or absolute) 
 # base path where the generated documentation will be put. 
diff --git a/src/arch/arm/insts/tme64ruby.cc b/src/arch/arm/insts/tme64ruby.cc
index 99481ba..f8d9481 100644
--- a/src/arch/arm/insts/tme64ruby.cc
+++ b/src/arch/arm/insts/tme64ruby.cc
@@ -109,15 +109,16 @@
 
         // checkpointing occurs in the outer transaction only
         if (htm_depth == 1) {
-            auto new_cpt = new HTMCheckpoint();
+            BaseHTMCheckpointPtr& cpt = xc->tcBase()->getHtmCheckpointPtr();
 
-            new_cpt->save(tc);
-            new_cpt->destinationRegister(dest);
+            HTMCheckpoint *armcpt =
+                dynamic_cast<HTMCheckpoint*>(cpt.get());
+            assert(armcpt != nullptr);
+
+            armcpt->save(tc);
+            armcpt->destinationRegister(dest);
 
             ArmISA::globalClearExclusive(tc);
-
-            xc->tcBase()->setHtmCheckpointPtr(
-                std::unique_ptr<BaseHTMCheckpoint>(new_cpt));
         }
 
         xc->setIntRegOperand(this, 0, (Dest64) & mask(intWidth));
diff --git a/src/arch/arm/isa.cc b/src/arch/arm/isa.cc
index cfef0ab..8ec2dc6 100644
--- a/src/arch/arm/isa.cc
+++ b/src/arch/arm/isa.cc
@@ -38,6 +38,7 @@
 #include "arch/arm/isa.hh"
 
 #include "arch/arm/faults.hh"
+#include "arch/arm/htm.hh"
 #include "arch/arm/interrupts.hh"
 #include "arch/arm/pmu.hh"
 #include "arch/arm/self_debug.hh"
@@ -439,9 +440,15 @@
 {
     BaseISA::startup();
 
-    if (tc)
+    if (tc) {
         setupThreadContext();
 
+        if (haveTME) {
+            std::unique_ptr<BaseHTMCheckpoint> cpt(new HTMCheckpoint());
+            tc->setHtmCheckpointPtr(std::move(cpt));
+        }
+    }
+
     afterStartup = true;
 }
 
diff --git a/src/base/version.cc b/src/base/version.cc
index ff58ad1..8edb8c6 100644
--- a/src/base/version.cc
+++ b/src/base/version.cc
@@ -29,4 +29,4 @@
 /**
  * @ingroup api_base_utils
  */
-const char *gem5Version = "[DEVELOP-FOR-V20.1]";
+const char *gem5Version = "20.1.0.0";
diff --git a/src/cpu/o3/thread_context_impl.hh b/src/cpu/o3/thread_context_impl.hh
index 005aa57..bea4dc7 100644
--- a/src/cpu/o3/thread_context_impl.hh
+++ b/src/cpu/o3/thread_context_impl.hh
@@ -347,7 +347,6 @@
 void
 O3ThreadContext<Impl>::setHtmCheckpointPtr(BaseHTMCheckpointPtr new_cpt)
 {
-    assert(!thread->htmCheckpoint->valid());
     thread->htmCheckpoint = std::move(new_cpt);
 }
 
diff --git a/src/cpu/simple_thread.cc b/src/cpu/simple_thread.cc
index 28a1c80..b9b69d8 100644
--- a/src/cpu/simple_thread.cc
+++ b/src/cpu/simple_thread.cc
@@ -196,6 +196,5 @@
 void
 SimpleThread::setHtmCheckpointPtr(BaseHTMCheckpointPtr new_cpt)
 {
-    assert(!_htmCheckpoint->valid());
     _htmCheckpoint = std::move(new_cpt);
 }
diff --git a/src/mem/abstract_mem.cc b/src/mem/abstract_mem.cc
index a708c6c..10aea37 100644
--- a/src/mem/abstract_mem.cc
+++ b/src/mem/abstract_mem.cc
@@ -92,7 +92,8 @@
     panic_if(!image_range.isSubset(range), "%s: memory image %s doesn't fit.",
              name(), file);
 
-    PortProxy proxy([this](PacketPtr pkt) { functionalAccess(pkt); }, size());
+    PortProxy proxy([this](PacketPtr pkt) { functionalAccess(pkt); },
+                    system()->cacheLineSize());
 
     panic_if(!image.write(proxy), "%s: Unable to write image.");
 }
diff --git a/src/mem/ruby/common/BoolVec.cc b/src/mem/ruby/common/BoolVec.cc
index 603f714..1c29532 100644
--- a/src/mem/ruby/common/BoolVec.cc
+++ b/src/mem/ruby/common/BoolVec.cc
@@ -41,8 +41,8 @@
 #include <vector>
 
 std::ostream& operator<<(std::ostream& os, const BoolVec& myvector) {
-    for (const auto& it: myvector) {
-        os << " " << it;
+    for (const bool e: myvector) {
+        os << " " << e;
     }
     return os;
 }
diff --git a/src/mem/ruby/slicc_interface/RubySlicc_Util.hh b/src/mem/ruby/slicc_interface/RubySlicc_Util.hh
index 8ff8884..155d134 100644
--- a/src/mem/ruby/slicc_interface/RubySlicc_Util.hh
+++ b/src/mem/ruby/slicc_interface/RubySlicc_Util.hh
@@ -256,8 +256,8 @@
 countBoolVec(BoolVec bVec)
 {
     int count = 0;
-    for (const auto &it: bVec) {
-        if (it) {
+    for (const bool e: bVec) {
+        if (e) {
             count++;
         }
     }
diff --git a/src/mem/ruby/system/Sequencer.cc b/src/mem/ruby/system/Sequencer.cc
index 75c58d6..dbc85c4 100644
--- a/src/mem/ruby/system/Sequencer.cc
+++ b/src/mem/ruby/system/Sequencer.cc
@@ -167,7 +167,7 @@
     int total_outstanding = 0;
 
     for (const auto &table_entry : m_RequestTable) {
-        for (const auto seq_req : table_entry.second) {
+        for (const auto &seq_req : table_entry.second) {
             if (current_time - seq_req.issue_time < m_deadlock_threshold)
                 continue;
 
diff --git a/src/python/m5/simulate.py b/src/python/m5/simulate.py
index 698dfbc..080d725 100644
--- a/src/python/m5/simulate.py
+++ b/src/python/m5/simulate.py
@@ -175,7 +175,15 @@
     if _drain_manager.isDrained():
         _drain_manager.resume()
 
-    return _m5.event.simulate(*args, **kwargs)
+    # We flush stdout and stderr before and after the simulation to ensure the
+    # output arrive in order.
+    sys.stdout.flush()
+    sys.stderr.flush()
+    sim_out = _m5.event.simulate(*args, **kwargs)
+    sys.stdout.flush()
+    sys.stderr.flush()
+
+    return sim_out
 
 def drain():
     """Drain the simulator in preparation of a checkpoint or memory mode
diff --git a/src/sim/pseudo_inst.cc b/src/sim/pseudo_inst.cc
index 90db4bb..aacca73 100644
--- a/src/sim/pseudo_inst.cc
+++ b/src/sim/pseudo_inst.cc
@@ -103,7 +103,7 @@
 static inline void
 panicFsOnlyPseudoInst(const char *name)
 {
-    panic("Pseudo inst \"%s\" is only available in Full System mode.");
+    panic("Pseudo inst \"%s\" is only available in Full System mode.", name);
 }
 
 void
diff --git a/tests/gem5/cpu_tests/ref/Bubblesort b/tests/gem5/cpu_tests/ref/Bubblesort
index 79d2ae3..76f4de0 100644
--- a/tests/gem5/cpu_tests/ref/Bubblesort
+++ b/tests/gem5/cpu_tests/ref/Bubblesort
@@ -1,6 +1,2 @@
-gem5 Simulator System.  http://gem5.org
-gem5 is copyrighted software; use the --copyright option for details.
-
-
 Global frequency set at 1000000000000 ticks per second
 -50000
diff --git a/tests/gem5/cpu_tests/ref/FloatMM b/tests/gem5/cpu_tests/ref/FloatMM
index 6539627..0f1d582 100644
--- a/tests/gem5/cpu_tests/ref/FloatMM
+++ b/tests/gem5/cpu_tests/ref/FloatMM
@@ -1,6 +1,2 @@
-gem5 Simulator System.  http://gem5.org
-gem5 is copyrighted software; use the --copyright option for details.
-
-
 Global frequency set at 1000000000000 ticks per second
 -776.000061
diff --git a/tests/gem5/dram-lowp/ref/simout b/tests/gem5/dram-lowp/ref/simout
index 5128ab4..6fdcf85 100644
--- a/tests/gem5/dram-lowp/ref/simout
+++ b/tests/gem5/dram-lowp/ref/simout
@@ -1,7 +1,3 @@
-gem5 Simulator System.  http://gem5.org
-gem5 is copyrighted software; use the --copyright option for details.
-
-
 Global frequency set at 1000000000000 ticks per second
 --- Done DRAM low power sweep ---
 Fixed params - 
diff --git a/tests/gem5/fixture.py b/tests/gem5/fixture.py
index e141d02..e8a67b8 100644
--- a/tests/gem5/fixture.py
+++ b/tests/gem5/fixture.py
@@ -42,6 +42,7 @@
 import sys
 import socket
 import threading
+import gzip
 
 from six.moves import urllib
 
@@ -260,11 +261,11 @@
         and downloads an updated version if it is needed.
     """
 
-    def __new__(cls, url, path, filename):
+    def __new__(cls, url, path, filename, gzip_decompress=False):
         target = joinpath(path, filename)
         return super(DownloadedProgram, cls).__new__(cls, target)
 
-    def _init(self, url, path, filename, **kwargs):
+    def _init(self, url, path, filename, gzip_decompress=False, **kwargs):
         """
         url: string
             The url of the archive
@@ -272,12 +273,16 @@
             The absolute path of the directory containing the archive
         filename: string
             The name of the archive
+        gzip_decompress: boolean
+            True if this target resource have been compressed using gzip and
+            is to be decompressed prior to usage.
         """
 
         self.url = url
         self.path = path
         self.filename = joinpath(path, filename)
         self.name = "Downloaded:" + self.filename
+        self.gzip_decompress = gzip_decompress
 
     def _download(self):
         import errno
@@ -288,7 +293,17 @@
             except OSError as e:
                 if e.errno != errno.EEXIST:
                     raise
-        urllib.request.urlretrieve(self.url, self.filename)
+        if self.gzip_decompress:
+            gzipped_filename = self.filename + ".gz"
+            urllib.request.urlretrieve(self.url, gzipped_filename)
+
+            with open(self.filename, 'w') as outfile:
+                with gzip.open(gzipped_filename, 'r') as infile:
+                    shutil.copyfileobj(infile, outfile)
+
+            os.remove(gzipped_filename)
+        else:
+            urllib.request.urlretrieve(self.url, self.filename)
 
     def _getremotetime(self):
         import datetime, time
diff --git a/tests/gem5/hello_se/ref/simerr b/tests/gem5/hello_se/ref/simerr
deleted file mode 100644
index e69de29..0000000
--- a/tests/gem5/hello_se/ref/simerr
+++ /dev/null
diff --git a/tests/gem5/hello_se/ref/simout b/tests/gem5/hello_se/ref/simout
index a38e288..9e8cf27 100644
--- a/tests/gem5/hello_se/ref/simout
+++ b/tests/gem5/hello_se/ref/simout
@@ -1,7 +1,3 @@
-gem5 Simulator System.  http://gem5.org
-gem5 is copyrighted software; use the --copyright option for details.
-
-
 Global frequency set at 1000000000000 ticks per second
 **** REAL SIMULATION ****
 Hello world!
diff --git a/tests/gem5/insttest_se/ref/sparc/linux/insttest/simout b/tests/gem5/insttest_se/ref/sparc/linux/insttest/simout
index 4665746..81a0b92 100644
--- a/tests/gem5/insttest_se/ref/sparc/linux/insttest/simout
+++ b/tests/gem5/insttest_se/ref/sparc/linux/insttest/simout
@@ -1,7 +1,3 @@
-gem5 Simulator System.  http://gem5.org
-gem5 is copyrighted software; use the --copyright option for details.
-
-
 Global frequency set at 1000000000000 ticks per second
 **** REAL SIMULATION ****
 Begining test of difficult SPARC instructions...
diff --git a/tests/gem5/learning_gem5/ref/hello b/tests/gem5/learning_gem5/ref/hello
index 0f0a7d6..bcdd7b9 100644
--- a/tests/gem5/learning_gem5/ref/hello
+++ b/tests/gem5/learning_gem5/ref/hello
@@ -1,7 +1,3 @@
-gem5 Simulator System.  http://gem5.org
-gem5 is copyrighted software; use the --copyright option for details.
-
-
 Global frequency set at 1000000000000 ticks per second
 Beginning simulation!
 Hello world!
diff --git a/tests/gem5/learning_gem5/ref/hello_goodbye b/tests/gem5/learning_gem5/ref/hello_goodbye
index 8e80377..cdaace8 100644
--- a/tests/gem5/learning_gem5/ref/hello_goodbye
+++ b/tests/gem5/learning_gem5/ref/hello_goodbye
@@ -1,7 +1,3 @@
-gem5 Simulator System.  http://gem5.org
-gem5 is copyrighted software; use the --copyright option for details.
-
-
 Global frequency set at 1000000000000 ticks per second
 Beginning simulation!
 Exiting @ tick 10944163 because Goodbye hello!! Goodbye hello!! Goodbye hello!! Goodbye hello!! Goodbye hello!! Goodbye hello!! Goo
diff --git a/tests/gem5/learning_gem5/ref/simple b/tests/gem5/learning_gem5/ref/simple
index b4c614a..71a3d62 100644
--- a/tests/gem5/learning_gem5/ref/simple
+++ b/tests/gem5/learning_gem5/ref/simple
@@ -1,7 +1,3 @@
-gem5 Simulator System.  http://gem5.org
-gem5 is copyrighted software; use the --copyright option for details.
-
-
 Global frequency set at 1000000000000 ticks per second
 Hello World! From a SimObject!
 Beginning simulation!
diff --git a/tests/gem5/learning_gem5/ref/test b/tests/gem5/learning_gem5/ref/test
index 794ccdd..309ac2f 100644
--- a/tests/gem5/learning_gem5/ref/test
+++ b/tests/gem5/learning_gem5/ref/test
@@ -1,7 +1,3 @@
-gem5 Simulator System.  http://gem5.org
-gem5 is copyrighted software; use the --copyright option for details.
-
-
 Global frequency set at 1000000000 ticks per second
 Beginning simulation!
 Exiting @ tick 9981 because Ruby Tester completed
diff --git a/tests/gem5/learning_gem5/ref/threads b/tests/gem5/learning_gem5/ref/threads
index 18a47fd..841ad73 100644
--- a/tests/gem5/learning_gem5/ref/threads
+++ b/tests/gem5/learning_gem5/ref/threads
@@ -1,7 +1,3 @@
-gem5 Simulator System.  http://gem5.org
-gem5 is copyrighted software; use the --copyright option for details.
-
-
 Global frequency set at 1000000000000 ticks per second
 Beginning simulation!
 Running on 2 cores. with 100 values
diff --git a/tests/gem5/m5threads_test_atomic/ref/sparc64/simout b/tests/gem5/m5threads_test_atomic/ref/sparc64/simout
index c6b51ca..dbe1405 100644
--- a/tests/gem5/m5threads_test_atomic/ref/sparc64/simout
+++ b/tests/gem5/m5threads_test_atomic/ref/sparc64/simout
@@ -1,7 +1,3 @@
-gem5 Simulator System.  http://gem5.org
-gem5 is copyrighted software; use the --copyright option for details.
-
-
 Global frequency set at 1000000000000 ticks per second
 Init done
 [Iteration 1, Thread 1] Got lock
diff --git a/tests/gem5/verifier.py b/tests/gem5/verifier.py
index ba4bd4f..60d44f3 100644
--- a/tests/gem5/verifier.py
+++ b/tests/gem5/verifier.py
@@ -115,6 +115,9 @@
 class MatchStdout(DerivedGoldStandard):
     _file = constants.gem5_simulation_stdout
     _default_ignore_regex = [
+            re.compile('^\s+$'), # Remove blank lines.
+            re.compile('^gem5 Simulator System'),
+            re.compile('^gem5 is copyrighted software'),
             re.compile('^Redirecting (stdout|stderr) to'),
             re.compile('^gem5 version '),
             re.compile('^gem5 compiled '),
diff --git a/tests/gem5/x86-boot-tests/test_linux_boot.py b/tests/gem5/x86-boot-tests/test_linux_boot.py
index 0e66659..d73f3a1 100644
--- a/tests/gem5/x86-boot-tests/test_linux_boot.py
+++ b/tests/gem5/x86-boot-tests/test_linux_boot.py
@@ -34,13 +34,13 @@
     base_path = joinpath(absdirpath(__file__), '..', 'resources',
             'ubuntu-boot')
 
-image_url = config.resource_url + '/images/x86/ubuntu-18-04/base.img'
+image_url = config.resource_url + '/images/x86/ubuntu-18-04/base.img.gz'
 kernel_url = config.resource_url + '/kernels/x86/static/vmlinux-4.19.83'
 
 image_name = 'ubuntu-18-04-base.img'
 kernel_name = 'vmlinux-4.19.83' # 4.19 is LTS (Projected EOL: Dec, 2020)
 
-image = DownloadedProgram(image_url, base_path, image_name)
+image = DownloadedProgram(image_url, base_path, image_name, True)
 kernel = DownloadedProgram(kernel_url, base_path, kernel_name)