diff --git a/3rdparty/ext_eigen3/CMakeLists.txt b/3rdparty/ext_eigen3/CMakeLists.txt
index e5c38c3cc4..2c2d16f346 100644
--- a/3rdparty/ext_eigen3/CMakeLists.txt
+++ b/3rdparty/ext_eigen3/CMakeLists.txt
@@ -1,13 +1,14 @@
 SET(EXTPREFIX_eigen3 "${EXTPREFIX}" )
 ExternalProject_Add( ext_eigen3
     DOWNLOAD_DIR ${EXTERNALS_DOWNLOAD_DIR}
+    # eigen 3.3.4: bitbucket does weird things when downloading.
     URL http://files.kde.org/krita/build/dependencies/eigen-3.3.7.tar.bz2
     URL_MD5 05b1f7511c93980c385ebe11bd3c93fa
 
     INSTALL_DIR ${EXTPREFIX_eigen3}
     PATCH_COMMAND ${PATCH_COMMAND} -p1 -i ${CMAKE_CURRENT_SOURCE_DIR}/dart.diff
         COMMAND ${PATCH_COMMAND} -p1 -i ${CMAKE_CURRENT_SOURCE_DIR}/no_tests.diff 
     CMAKE_ARGS -DCMAKE_INSTALL_PREFIX=${EXTPREFIX_eigen3} -DCMAKE_BUILD_TYPE=${GLOBAL_BUILD_TYPE} ${GLOBAL_PROFILE}
 
     UPDATE_COMMAND ""
 )
diff --git a/3rdparty/ext_eigen3/dart.diff b/3rdparty/ext_eigen3/dart.diff
index 15770fbe18..4df1bdf519 100644
--- a/3rdparty/ext_eigen3/dart.diff
+++ b/3rdparty/ext_eigen3/dart.diff
@@ -1,24 +1,24 @@
 diff --git a/cmake/EigenConfigureTesting.cmake b/cmake/EigenConfigureTesting.cmake
-index 2b11d83..8cf56ff 100644
+index 3a82439..4c28246 100644
 --- a/cmake/EigenConfigureTesting.cmake
 +++ b/cmake/EigenConfigureTesting.cmake
-@@ -26,19 +26,6 @@ include(CTest)
- 
- set(EIGEN_TEST_BUILD_FLAGS " " CACHE STRING "Options passed to the build command of unit tests")
+@@ -21,19 +21,6 @@ set(EIGEN_TEST_BUILD_FLAGS "" CACHE STRING "Options passed to the build command
+ set(EIGEN_DASHBOARD_BUILD_TARGET "buildtests" CACHE STRING "Target to be built in dashboard mode, default is buildtests")
+ set(EIGEN_CTEST_ERROR_EXCEPTION "" CACHE STRING "Regular expression for build error messages to be filtered out")
  
 -# Overwrite default DartConfiguration.tcl such that ctest can build our unit tests.
 -# Recall that our unit tests are not in the "all" target, so we have to explicitely ask ctest to build our custom 'buildtests' target.
 -# At this stage, we can also add custom flags to the build tool through the user defined EIGEN_TEST_BUILD_FLAGS variable.
 -file(READ  "${CMAKE_CURRENT_BINARY_DIR}/DartConfiguration.tcl" EIGEN_DART_CONFIG_FILE)
 -# try to grab the default flags
 -string(REGEX MATCH "MakeCommand:.*-- (.*)\nDefaultCTestConfigurationType" EIGEN_DUMMY ${EIGEN_DART_CONFIG_FILE})
 -if(NOT CMAKE_MATCH_1)
 -string(REGEX MATCH "MakeCommand:.*[^c]make (.*)\nDefaultCTestConfigurationType" EIGEN_DUMMY ${EIGEN_DART_CONFIG_FILE})
 -endif()
--string(REGEX REPLACE "MakeCommand:.*DefaultCTestConfigurationType" "MakeCommand: ${CMAKE_COMMAND} --build . --target buildtests --config \"\${CTEST_CONFIGURATION_TYPE}\" -- ${CMAKE_MATCH_1} ${EIGEN_TEST_BUILD_FLAGS}\nDefaultCTestConfigurationType"
+-string(REGEX REPLACE "MakeCommand:.*DefaultCTestConfigurationType" "MakeCommand: ${CMAKE_COMMAND} --build . --target ${EIGEN_DASHBOARD_BUILD_TARGET} --config \"\${CTEST_CONFIGURATION_TYPE}\" -- ${CMAKE_MATCH_1} ${EIGEN_TEST_BUILD_FLAGS}\nDefaultCTestConfigurationType"
 -       EIGEN_DART_CONFIG_FILE2 ${EIGEN_DART_CONFIG_FILE})
 -file(WRITE "${CMAKE_CURRENT_BINARY_DIR}/DartConfiguration.tcl" ${EIGEN_DART_CONFIG_FILE2})
 -
  configure_file(${CMAKE_CURRENT_SOURCE_DIR}/CTestCustom.cmake.in ${CMAKE_BINARY_DIR}/CTestCustom.cmake)
  
  # some documentation of this function would be nice
diff --git a/3rdparty/ext_eigen3/no_tests.diff b/3rdparty/ext_eigen3/no_tests.diff
index d943dab6d5..d20f5a0110 100644
--- a/3rdparty/ext_eigen3/no_tests.diff
+++ b/3rdparty/ext_eigen3/no_tests.diff
@@ -1,35 +1,13 @@
-commit 09b46c2a9acb0b7cb52968599499cb19fa5d8904
-Author: Boudewijn Rempt <boud@valdyas.org>
-Date:   Fri Jan 5 16:09:39 2018 +0100
-
-    Disable tests: they need blas
-
 diff --git a/CMakeLists.txt b/CMakeLists.txt
-index f584002..dcb461b 100644
+index 2bfb6d5..81bffbe 100644
 --- a/CMakeLists.txt
 +++ b/CMakeLists.txt
-@@ -418,24 +418,6 @@ add_subdirectory(doc EXCLUDE_FROM_ALL)
+@@ -435,7 +435,7 @@ add_subdirectory(Eigen)
  
- include(EigenConfigureTesting)
+ add_subdirectory(doc EXCLUDE_FROM_ALL)
+ 
+-option(BUILD_TESTING "Enable creation of Eigen tests." ON)
++option(BUILD_TESTING "Enable creation of Eigen tests." OFF)
+ if(BUILD_TESTING)
+   include(EigenConfigureTesting)
  
--# fixme, not sure this line is still needed:
--enable_testing() # must be called from the root CMakeLists, see man page
--
--
--if(EIGEN_LEAVE_TEST_IN_ALL_TARGET)
--  add_subdirectory(test) # can't do EXCLUDE_FROM_ALL here, breaks CTest
--else()
--  add_subdirectory(test EXCLUDE_FROM_ALL)
--endif()
--
--if(EIGEN_LEAVE_TEST_IN_ALL_TARGET)
--  add_subdirectory(blas)
--  add_subdirectory(lapack)
--else()
--  add_subdirectory(blas EXCLUDE_FROM_ALL)
--  add_subdirectory(lapack EXCLUDE_FROM_ALL)
--endif()
--
- # add SYCL
- option(EIGEN_TEST_SYCL "Add Sycl support." OFF)
- if(EIGEN_TEST_SYCL)