diff --git a/GPU/GPUTracking/CMakeLists.txt b/GPU/GPUTracking/CMakeLists.txt
index 816d578fb31a3..14118d9b71e9c 100644
--- a/GPU/GPUTracking/CMakeLists.txt
+++ b/GPU/GPUTracking/CMakeLists.txt
@@ -107,6 +107,25 @@ set(SRCS_NO_H SectorTracker/GPUTPCTrackerDump.cxx
               Global/GPUChainTrackingDebugAndProfiling.cxx
               Global/GPUChainTrackingIO.cxx)
 
+if(GPUCA_OVERRIDE_PARAMETER_FILE)
+    set(GPU_PARAM_JSON ${GPUCA_OVERRIDE_PARAMETER_FILE})
+else()
+    set(GPU_PARAM_JSON ${CMAKE_CURRENT_SOURCE_DIR}/Definitions/Parameters/GPUParameters.csv)
+endif()
+set_property(DIRECTORY APPEND PROPERTY CMAKE_CONFIGURE_DEPENDS "${GPU_PARAM_JSON}")
+
+get_filename_component(GPU_PARAM_JSON_EXT ${GPU_PARAM_JSON} EXT)
+string(TOLOWER "${GPU_PARAM_JSON_EXT}" GPU_PARAM_JSON_EXT)
+if(GPU_PARAM_JSON_EXT STREQUAL .csv)
+    execute_process(
+        COMMAND ${CMAKE_CURRENT_SOURCE_DIR}/Definitions/Parameters/csv_to_json.sh "${GPU_PARAM_JSON}"
+        OUTPUT_FILE ${CMAKE_CURRENT_BINARY_DIR}/gpu_parameters.json
+        WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}
+    )
+    message(STATUS "Converted ${GPU_PARAM_JSON} to ${CMAKE_CURRENT_BINARY_DIR}/gpu_parameters.json")
+    set(GPU_PARAM_JSON ${CMAKE_CURRENT_BINARY_DIR}/gpu_parameters.json)
+endif()
+
 set(ON_THE_FLY_DIR ${CMAKE_CURRENT_BINARY_DIR}/include_gpu_onthefly)
 file(MAKE_DIRECTORY ${ON_THE_FLY_DIR})
 include(cmake/gpu_param_header_generator.cmake)
@@ -410,12 +429,11 @@ target_sources(${targetName}
                BASE_DIRS ${CMAKE_CURRENT_BINARY_DIR})
 
 make_directory(${CMAKE_CURRENT_BINARY_DIR}/genGPUArch)
-set(GPU_CONST_PARAM_ARCHITECTUES AMPERE TURING VEGA MI100)
 set(GPU_CONST_PARAM_FILES "")
+set(GPU_ARCH_PARAMS_HEADER ${CMAKE_CURRENT_BINARY_DIR}/genGPUArch/GPUDefParametersDefaults_OnTheFly.h)
+generate_gpu_param_header("ALL" ${GPU_ARCH_PARAMS_HEADER} "GPU_CONST_PARAM_ARCHITECTUES")
 foreach(GPU_ARCH ${GPU_CONST_PARAM_ARCHITECTUES})
   set(PARAMFILE ${CMAKE_CURRENT_BINARY_DIR}/genGPUArch/gpu_const_param_${GPU_ARCH}.par)
-  set(GPU_ARCH_PARAMS_HEADER ${CMAKE_CURRENT_BINARY_DIR}/genGPUArch/GPUDefParametersDefaults_${GPU_ARCH}.h)
-  generate_gpu_param_header(${GPU_ARCH} ${GPU_ARCH_PARAMS_HEADER})
   add_custom_command(
     OUTPUT ${PARAMFILE}
     COMMAND bash -c
diff --git a/GPU/GPUTracking/Definitions/Parameters/GPUParameters.csv b/GPU/GPUTracking/Definitions/Parameters/GPUParameters.csv
new file mode 100644
index 0000000000000..5afa99554f5d0
--- /dev/null
+++ b/GPU/GPUTracking/Definitions/Parameters/GPUParameters.csv
@@ -0,0 +1,113 @@
+Architecture,default,MI100,VEGA,TAHITI,TESLA,FERMI,PASCAL,KEPLER,AMPERE,TURING,default_cpu
+,,,,,,,,,,,
+CORE:,,,,,,,,,,,
+WARP_SIZE,32,64,64,32,32,32,32,32,32,32,
+THREAD_COUNT_DEFAULT,256,256,256,,,,,,512,512,
+,,,,,,,,,,,
+LB:,,,,,,,,,,,
+GPUTPCCreateTrackingData,256,"[256, 7]","[192, 2]",,,,,,384,256,
+GPUTPCTrackletConstructor,256,"[768, 8]","[512, 10]","[256, 2]","[256, 1]","[256, 2]","[1024, 2]","[512, 4]","[256, 2]","[256, 2]",
+GPUTPCTrackletSelector,256,"[384, 5]","[192, 10]","[256, 3]","[256, 1]","[256, 3]","[512, 4]","[256, 3]","[192, 3]","[192, 3]",
+GPUTPCNeighboursFinder,256,"[192, 8]","[960, 8]",256,256,256,512,256,"[640, 1]","[640, 1]",
+GPUTPCNeighboursCleaner,256,"[128, 5]","[384, 9]",256,256,256,256,256,512,512,
+GPUTPCExtrapolationTracking,256,"[256, 7]","[256, 2]",,,,,,"[128, 4]","[192, 2]",
+GPUTRDTrackerKernels_gpuVersion,512,,,,,,,,,,
+GPUTPCCreateOccupancyMap_fill,256,,,,,,,,,,
+GPUTPCCreateOccupancyMap_fold,256,,,,,,,,,,
+GPUTRDTrackerKernels_o2Version,512,,,,,,,,,,
+GPUTPCCompressionKernels_step0attached,256,"[128, 1]","[64, 2]",,,,,,"[64, 2]",128,
+GPUTPCCompressionKernels_step1unattached,256,"[512, 2]","[512, 2]",,,,,,"[512, 3]","[512, 2]",
+GPUTPCDecompressionKernels_step0attached,256,"[128, 2]","[128, 2]",,,,,,"[32, 1]","[32, 1]",
+GPUTPCDecompressionKernels_step1unattached,256,"[64, 2]","[64, 2]",,,,,,"[32, 1]","[32, 1]",
+GPUTPCDecompressionUtilKernels_sortPerSectorRow,256,,,,,,,,,,
+GPUTPCDecompressionUtilKernels_countFilteredClusters,256,,,,,,,,,,
+GPUTPCDecompressionUtilKernels_storeFilteredClusters,256,,,,,,,,,,
+GPUTPCCFDecodeZS,"[128, 4]","[64, 4]","[64, 1]",,,,,,"[64, 10]","[64, 8]",
+GPUTPCCFDecodeZSLink,"""GPUCA_WARP_SIZE""","""GPUCA_WARP_SIZE""","""GPUCA_WARP_SIZE""",,,,,,"""GPUCA_WARP_SIZE""","""GPUCA_WARP_SIZE""",
+GPUTPCCFDecodeZSDenseLink,"""GPUCA_WARP_SIZE""","[""GPUCA_WARP_SIZE"", 4]","[""GPUCA_WARP_SIZE"", 14]",,,,,,"""GPUCA_WARP_SIZE""","""GPUCA_WARP_SIZE""",
+GPUTPCCFGather,"[1024, 1]","[1024, 5]","[1024, 1]",,,,,,"[1024, 1]","[1024, 1]",
+COMPRESSION_GATHER,1024,1024,1024,,,,,,1024,1024,
+GPUTPCGMMergerTrackFit,256,"[192, 2]","[64, 7]",,,,,,"[64, 4]","[32, 8]",
+GPUTPCGMMergerFollowLoopers,256,"[256, 5]","[256, 4]",,,,,,"[64, 12]","[128, 4]",
+GPUTPCGMMergerSectorRefit,256,"[64, 4]","[256, 2]",,,,,,"[32, 6]","[64, 5]",
+GPUTPCGMMergerUnpackResetIds,256,256,256,,,,,,256,256,
+GPUTPCGMMergerUnpackGlobal,256,256,256,,,,,,256,256,
+GPUTPCGMMergerResolve_step0,256,512,256,,,,,,256,256,
+GPUTPCGMMergerResolve_step1,256,512,256,,,,,,256,256,
+GPUTPCGMMergerResolve_step2,256,512,256,,,,,,256,256,
+GPUTPCGMMergerResolve_step3,256,512,256,,,,,,256,256,
+GPUTPCGMMergerResolve_step4,256,512,256,,,,,,"[256, 4]","[256, 4]",
+GPUTPCGMMergerClearLinks,256,256,256,,,,,,256,256,
+GPUTPCGMMergerMergeWithinPrepare,256,256,256,,,,,,256,256,
+GPUTPCGMMergerMergeSectorsPrepare,256,256,256,,,,,,"[256, 2]","[256, 2]",
+GPUTPCGMMergerMergeBorders_step0,256,512,256,,,,,,192,192,
+GPUTPCGMMergerMergeBorders_step2,256,512,256,,,,,,"[64, 2]",256,
+GPUTPCGMMergerMergeCE,256,512,256,,,,,,256,256,
+GPUTPCGMMergerLinkExtrapolatedTracks,256,256,256,,,,,,256,256,
+GPUTPCGMMergerCollect,256,"[768, 1]","[1024, 1]",,,,,,"[256, 2]","[128, 2]",
+GPUTPCGMMergerSortTracksPrepare,256,256,256,,,,,,256,256,
+GPUTPCGMMergerPrepareForFit_step0,256,256,256,,,,,,256,256,
+GPUTPCGMMergerPrepareForFit_step1,256,256,256,,,,,,256,256,
+GPUTPCGMMergerPrepareForFit_step2,256,256,256,,,,,,256,256,
+GPUTPCGMMergerFinalize_step0,256,,256,,,,,,,,
+GPUTPCGMMergerFinalize_step1,256,,256,,,,,,,,
+GPUTPCGMMergerFinalize_step2,256,,256,,,,,,,,
+GPUTPCGMMergerMergeLoopers_step0,256,,,,,,,,,,
+GPUTPCGMMergerMergeLoopers_step1,256,,,,,,,,,,
+GPUTPCGMMergerMergeLoopers_step2,256,,,,,,,,,,
+GPUTPCGMO2Output_prepare,256,,,,,,,,,,
+GPUTPCGMO2Output_output,256,,,,,,,,,,
+GPUTPCStartHitsFinder,256,"[1024, 2]","[1024, 7]",256,256,256,256,256,512,512,
+GPUTPCStartHitsSorter,256,"[1024, 5]","[512, 7]",256,256,256,256,256,"[512, 1]","[512, 1]",
+GPUTPCCFCheckPadBaseline,576,"[576, 2]","[576, 2]",,,,,,"[576, 2]",,
+GPUTPCCFChargeMapFiller_fillIndexMap,512,512,512,,,,,,448,,
+GPUTPCCFChargeMapFiller_fillFromDigits,512,512,512,,,,,,448,,
+GPUTPCCFChargeMapFiller_findFragmentStart,512,512,512,,,,,,448,,
+GPUTPCCFPeakFinder,512,"[512, 9]","[512, 4]",,,,,,128,,
+GPUTPCCFNoiseSuppression,512,512,512,,,,,,448,,
+GPUTPCCFDeconvolution,512,"[512, 5]","[512, 5]",,,,,,384,,
+GPUTPCCFClusterizer,512,"[448, 3]","[512, 2]",,,,,,448,,
+GPUTPCNNClusterizerKernels,512,,,,,,,,,,
+GPUTrackingRefitKernel_mode0asGPU,256,,,,,,,,,,
+GPUTrackingRefitKernel_mode1asTrackParCov,256,,,,,,,,,,
+GPUMemClean16,"[""GPUCA_THREAD_COUNT_DEFAULT"", 1]",,,,,,,,,,
+GPUitoa,"[""GPUCA_THREAD_COUNT_DEFAULT"", 1]",,,,,,,,,,
+GPUTPCCFNoiseSuppression_noiseSuppression,"""GPUCA_LB_GPUTPCCFNoiseSuppression""",,,,,,,,,,
+GPUTPCCFNoiseSuppression_updatePeaks,"""GPUCA_LB_GPUTPCCFNoiseSuppression""",,,,,,,,,,
+GPUTPCNNClusterizerKernels_runCfClusterizer,"""GPUCA_LB_GPUTPCNNClusterizerKernels""",,,,,,,,,,
+GPUTPCNNClusterizerKernels_fillInputNNCPU,"""GPUCA_LB_GPUTPCNNClusterizerKernels""",,,,,,,,,,
+GPUTPCNNClusterizerKernels_fillInputNNGPU,1024,,,,,,,,,,
+GPUTPCNNClusterizerKernels_determineClass1Labels,"""GPUCA_LB_GPUTPCNNClusterizerKernels""",,,,,,,,,,
+GPUTPCNNClusterizerKernels_determineClass2Labels,"""GPUCA_LB_GPUTPCNNClusterizerKernels""",,,,,,,,,,
+GPUTPCNNClusterizerKernels_publishClass1Regression,"""GPUCA_LB_GPUTPCNNClusterizerKernels""",,,,,,,,,,
+GPUTPCNNClusterizerKernels_publishClass2Regression,"""GPUCA_LB_GPUTPCNNClusterizerKernels""",,,,,,,,,,
+GPUTPCNNClusterizerKernels_publishDeconvolutionFlags,"""GPUCA_LB_GPUTPCNNClusterizerKernels""",,,,,,,,,,
+GPUTPCCFStreamCompaction_scanStart,"""GPUCA_PAR_CF_SCAN_WORKGROUP_SIZE""",,,,,,,,,,
+GPUTPCCFStreamCompaction_scanUp,"""GPUCA_PAR_CF_SCAN_WORKGROUP_SIZE""",,,,,,,,,,
+GPUTPCCFStreamCompaction_scanTop,"""GPUCA_PAR_CF_SCAN_WORKGROUP_SIZE""",,,,,,,,,,
+GPUTPCCFStreamCompaction_scanDown,"""GPUCA_PAR_CF_SCAN_WORKGROUP_SIZE""",,,,,,,,,,
+GPUTPCCFStreamCompaction_compactDigits,"""GPUCA_PAR_CF_SCAN_WORKGROUP_SIZE""",,,,,,,,,,
+GPUTPCCompressionGatherKernels_unbuffered,"""GPUCA_LB_COMPRESSION_GATHER""",,,,,,,,,,
+GPUTPCCompressionGatherKernels_buffered32,"""GPUCA_LB_COMPRESSION_GATHER""",,,,,,,,,,
+GPUTPCCompressionGatherKernels_buffered64,"""GPUCA_LB_COMPRESSION_GATHER""",,,,,,,,,,
+GPUTPCCompressionGatherKernels_buffered128,"""GPUCA_LB_COMPRESSION_GATHER""",,,,,,,,,,
+GPUTPCCompressionGatherKernels_multiBlock,"""GPUCA_LB_COMPRESSION_GATHER""",,,,,,,,,,
+GPUTPCGMMergerFinalize_0,256,256,,,,,,,256,256,
+GPUTPCGMMergerFinalize_1,256,256,,,,,,,256,256,
+GPUTPCGMMergerFinalize_2,256,256,,,,,,,256,256,
+,,,,,,,,,,,
+PAR:,,,,,,,,,,,
+AMD_EUS_PER_CU,0,4,4,,,,,,,,0
+SORT_STARTHITS,1,,,,,,,,,,0
+NEIGHBOURS_FINDER_MAX_NNEIGHUP,6,10,4,,,,,,4,4,0
+NEIGHBOURS_FINDER_UNROLL_GLOBAL,4,4,2,,,,,,,,0
+NEIGHBOURS_FINDER_UNROLL_SHARED,1,0,0,,,,,,,,0
+TRACKLET_SELECTOR_HITS_REG_SIZE,12,9,27,,,,,,20,20,0
+ALTERNATE_BORDER_SORT,0,1,1,,,,,,1,1,0
+SORT_BEFORE_FIT,0,1,1,,,,,,1,1,0
+NO_ATOMIC_PRECHECK,0,1,1,,,,,,1,1,0
+DEDX_STORAGE_TYPE,"""float""","""uint16_t""","""uint16_t""",,,,,,"""uint16_t""","""uint16_t""","""float"""
+MERGER_INTERPOLATION_ERROR_TYPE,"""float""","""half""","""half""",,,,,,"""half""","""half""","""float"""
+COMP_GATHER_KERNEL,0,4,4,,,,,,4,4,0
+COMP_GATHER_MODE,2,3,3,,,,,,3,3,0
+CF_SCAN_WORKGROUP_SIZE,512,,,,,,,,,,0
diff --git a/GPU/GPUTracking/Definitions/Parameters/GPUParameters.json b/GPU/GPUTracking/Definitions/Parameters/GPUParameters.json.example
similarity index 99%
rename from GPU/GPUTracking/Definitions/Parameters/GPUParameters.json
rename to GPU/GPUTracking/Definitions/Parameters/GPUParameters.json.example
index 285919559c04c..3c6f1af1aab2f 100644
--- a/GPU/GPUTracking/Definitions/Parameters/GPUParameters.json
+++ b/GPU/GPUTracking/Definitions/Parameters/GPUParameters.json.example
@@ -2,7 +2,6 @@
   "CORE": {
     "WARP_SIZE": {
       "default":      32,
-      "default_cpu":  1,
       "MI100":        64,
       "VEGA":         64,
       "TAHITI":       32,
diff --git a/GPU/GPUTracking/Definitions/Parameters/csv_to_json.sh b/GPU/GPUTracking/Definitions/Parameters/csv_to_json.sh
index ae9d3b7704284..373bd18ba7cd4 100755
--- a/GPU/GPUTracking/Definitions/Parameters/csv_to_json.sh
+++ b/GPU/GPUTracking/Definitions/Parameters/csv_to_json.sh
@@ -2,7 +2,13 @@
 
 [[ -z $1 ]] && { echo "Usage: csv_to_json.sh CSV_FILE"; exit 1; }
 
-awk -vFPAT='([^,]*)|(\"([^\"]|\"\")*\")' \
+DELIM=$'\xFF'
+sed -E \
+  ':loop
+   s/^(([^"]*"[^"]*")*[^"]*),/\1'$DELIM'/;
+   t loop' \
+  $1 | \
+awk -F$DELIM \
   'BEGIN {
      print "{"
    } {
@@ -42,5 +48,4 @@ awk -vFPAT='([^,]*)|(\"([^\"]|\"\")*\")' \
      if (paramprinted) print "\n    }"
      if (catprinted) print "  }"
      print "}"
-   }' \
-   $1
+   }'
diff --git a/GPU/GPUTracking/Standalone/cmake/config.cmake b/GPU/GPUTracking/Standalone/cmake/config.cmake
index ca723063b6d3b..9355311db617c 100644
--- a/GPU/GPUTracking/Standalone/cmake/config.cmake
+++ b/GPU/GPUTracking/Standalone/cmake/config.cmake
@@ -41,3 +41,4 @@ set(CUDA_COMPUTETARGET "default")           # 86 89
 #set(GPUCA_CONFIG_COMPILER gcc)             # gcc / clang
 #set(GPUCA_CONFIG_WERROR 1)
 #add_definitions(-DGPUCA_GPU_DEBUG_PRINT)
+#set(GPUCA_OVERRIDE_PARAMETER_FILE "foo.csv")
diff --git a/GPU/GPUTracking/cmake/gpu_param_header_generator.cmake b/GPU/GPUTracking/cmake/gpu_param_header_generator.cmake
index 3770e30f2583c..e79a96034103d 100644
--- a/GPU/GPUTracking/cmake/gpu_param_header_generator.cmake
+++ b/GPU/GPUTracking/cmake/gpu_param_header_generator.cmake
@@ -12,7 +12,12 @@
 # file gpu_param_header_generator.cmake
 # author Gabriele Cimador
 
-function(generate_macros json_content header types arch_key use_ifndef_guard)
+function(generate_macros json_content output types arch_list arch_list_output)
+    foreach(arch IN LISTS arch_list)
+        set(OUTPUT_TMP_${arch} "")
+    endforeach()
+    set(arch_list_output_tmp)
+    list(FIND arch_list "ALL" do_all_architectures)
     foreach(TYPE IN LISTS types)
         string(JSON n_params LENGTH "${json_content}" "${TYPE}")
         math(EXPR last "${n_params} - 1")
@@ -22,8 +27,19 @@ function(generate_macros json_content header types arch_key use_ifndef_guard)
             math(EXPR last_arch "${n_archs} - 1")
             foreach(iArch RANGE 0 ${last_arch})
                 string(JSON arch MEMBER "${JSON_CONTENT}" "${TYPE}" "${param_name}" "${iArch}")
-                if(arch STREQUAL "${arch_key}")
-                    string(JSON param_values GET "${JSON_CONTENT}" "${TYPE}" "${param_name}" "${arch_key}")
+                if(arch STREQUAL "default_cpu" AND NOT TYPE STREQUAL "PAR")
+                  message(FATAL_ERROR "Bogus entry ${param_name} for ${arch}")
+                endif()
+                if(do_all_architectures GREATER -1)
+                    if(arch_list_output AND NOT arch MATCHES ^default)
+                        list(APPEND arch_list_output_tmp "${arch}")
+                    endif()
+                    set(list_idx 0)
+                else()
+                    list(FIND arch_list "${arch}" list_idx)
+                endif()
+                if(list_idx GREATER -1)
+                    string(JSON param_values GET "${JSON_CONTENT}" "${TYPE}" "${param_name}" "${arch}")
                     if(TYPE STREQUAL "LB")
                         set(MACRO_NAME "GPUCA_LB_${param_name}")
                     elseif(TYPE STREQUAL "PAR")
@@ -36,20 +52,27 @@ function(generate_macros json_content header types arch_key use_ifndef_guard)
                     string(REGEX REPLACE " *\\]$" "" vals "${vals}")
                     string(REGEX REPLACE "\"" "" vals "${vals}")
                     set(MACRO_DEFINITION "#define ${MACRO_NAME} ${vals}")
-                    if(use_ifndef_guard)
+                    if(arch MATCHES ^default)
                         # fallback defaults are wrapped in #ifndef
-                        file(APPEND "${header}" "#ifndef ${MACRO_NAME}\n  ${MACRO_DEFINITION}\n#endif\n\n")
+                        string(APPEND OUTPUT_TMP_${arch} "#ifndef ${MACRO_NAME}\n  ${MACRO_DEFINITION}\n#endif\n\n")
                     else()
-                        file(APPEND "${header}" "${MACRO_DEFINITION}\n")
+                        string(APPEND OUTPUT_TMP_${arch} "${MACRO_DEFINITION}\n")
                     endif()
                 endif()
             endforeach()
         endforeach()
     endforeach()
+    foreach(arch IN LISTS arch_list)
+        set(${output}_${arch} "${OUTPUT_TMP_${arch}}" PARENT_SCOPE)
+    endforeach()
+    if(arch_list_output)
+        list(REMOVE_DUPLICATES arch_list_output_tmp)
+        list(SORT arch_list_output_tmp)
+        set(${arch_list_output} "${arch_list_output_tmp}" PARENT_SCOPE)
+    endif()
 endfunction()
 
 function(generate_gpu_param_header GPU_ARCH OUT_HEADER)
-    set(GPU_PARAM_JSON ${CMAKE_CURRENT_SOURCE_DIR}/Definitions/Parameters/GPUParameters.json)
     set(TARGET_ARCH "UNKNOWN")
     if(GPU_ARCH STREQUAL "AUTO")
         detect_gpu_arch("ALL")
@@ -57,42 +80,42 @@ function(generate_gpu_param_header GPU_ARCH OUT_HEADER)
         set(TARGET_ARCH ${GPU_ARCH})
     endif()
     file(READ "${GPU_PARAM_JSON}" JSON_CONTENT)
-    set(TMP_HEADER "${OUT_HEADER}.tmp")
-    file(WRITE "${TMP_HEADER}" "#ifndef GPUDEFPARAMETERSDEFAULTS_H\n#define GPUDEFPARAMETERSDEFAULTS_H\n\n")
-    file(APPEND "${TMP_HEADER}" "// This file is auto-generated from gpu_params.json. Do not edit directly.\n")
+    set(TMP_HEADER "#ifndef GPUDEFPARAMETERSDEFAULTS_H\n#define GPUDEFPARAMETERSDEFAULTS_H\n\n")
+    string(APPEND TMP_HEADER "// This file is auto-generated from gpu_params.json. Do not edit directly.\n")
     string(REPLACE "," ";" ARCH_LIST "${TARGET_ARCH}")
-    file(APPEND "${TMP_HEADER}" "// Architectures: ${TARGET_ARCH}\n\n")
-    file(APPEND "${TMP_HEADER}" "#if defined(GPUCA_GPUCODE) && !defined(GPUCA_GPUCODE_GENRTC) && !defined(GPUCA_GPUCODE_NO_LAUNCH_BOUNDS) // Avoid including for RTC generation besides normal include protection.\n\n")
+    string(APPEND TMP_HEADER "// Architectures: ${TARGET_ARCH}\n\n")
+    string(APPEND TMP_HEADER "#if defined(GPUCA_GPUCODE) && !defined(GPUCA_GPUCODE_GENRTC) && !defined(GPUCA_GPUCODE_NO_LAUNCH_BOUNDS) // Avoid including for RTC generation besides normal include protection.\n\n")
 
     # Types
     set(TYPES CORE LB PAR)
     # Per architecture definitions
-    set(_first TRUE)
+    generate_macros("${JSON_CONTENT}" TMP_OUTPUT "${TYPES}" "${ARCH_LIST};default;default_cpu" "JSON_ARCHITECTURES")
+    list(FIND ARCH_LIST "ALL" do_all_architectures)
+    if(ARGC GREATER 2)
+        set(${ARGV2} "${JSON_ARCHITECTURES}" PARENT_SCOPE)
+    endif()
+    if(do_all_architectures GREATER -1)
+        set(ARCH_LIST ${JSON_ARCHITECTURES})
+    endif()
+    string(APPEND TMP_HEADER "#if 0\n")
     foreach(ARCH IN LISTS ARCH_LIST)
-        if(_first)
-            file(APPEND "${TMP_HEADER}" "#if defined(GPUCA_GPUTYPE_${ARCH})\n\n")
-            set(_first FALSE)
-        else()
-            file(APPEND "${TMP_HEADER}" "#elif defined(GPUCA_GPUTYPE_${ARCH})\n\n")
-        endif()
-        generate_macros("${JSON_CONTENT}" "${TMP_HEADER}" "${TYPES}" "${ARCH}" "")
+        string(APPEND TMP_HEADER "\n#elif defined(GPUCA_GPUTYPE_${ARCH})\n")
+        string(APPEND TMP_HEADER ${TMP_OUTPUT_${ARCH}})
     endforeach()
-    if(NOT _first)
-        file(APPEND "${TMP_HEADER}" "#else\n#error GPU TYPE NOT SET\n#endif\n")
-    endif()
+    string(APPEND TMP_HEADER "#else\n#error GPU TYPE NOT SET\n#endif\n")
 
     # Default parameters
-    file(APPEND "${TMP_HEADER}" "\n// Default parameters if not defined for the target architecture\n\n")
-    generate_macros("${JSON_CONTENT}" "${TMP_HEADER}" "${TYPES}" "default" "use_ifndef_guard")
-    file(APPEND "${TMP_HEADER}" "#endif // defined(GPUCA_GPUCODE) && !defined(GPUCA_GPUCODE_GENRTC) && !defined(GPUCA_GPUCODE_NO_LAUNCH_BOUNDS)\n\n")
+    string(APPEND TMP_HEADER "\n// Default parameters if not defined for the target architecture\n\n")
+    string(APPEND TMP_HEADER ${TMP_OUTPUT_default})
+    string(APPEND TMP_HEADER "#endif // defined(GPUCA_GPUCODE) && !defined(GPUCA_GPUCODE_GENRTC) && !defined(GPUCA_GPUCODE_NO_LAUNCH_BOUNDS)\n\n")
 
     # CPU fallback
-    file(APPEND "${TMP_HEADER}" "#ifndef GPUCA_GPUCODE_GENRTC //Defaults for non-LB parameters also for CPU fallback\n\n")
-    generate_macros("${JSON_CONTENT}" "${TMP_HEADER}" "PAR" "default_cpu" "use_ifndef_guard")
-    file(APPEND "${TMP_HEADER}" "\n#endif // GPUCA_GPUCODE_GENRTC\n")
+    string(APPEND TMP_HEADER "#ifndef GPUCA_GPUCODE_GENRTC // Defaults for non-LB parameters also for CPU fallback\n\n")
+    string(APPEND TMP_HEADER ${TMP_OUTPUT_default_cpu})
+    string(APPEND TMP_HEADER "\n#endif // GPUCA_GPUCODE_GENRTC\n")
 
-    file(APPEND "${TMP_HEADER}" "\n#endif // GPUDEFPARAMETERSDEFAULTS_H\n")
-    file(RENAME "${TMP_HEADER}" "${OUT_HEADER}")
+    string(APPEND TMP_HEADER "\n#endif // GPUDEFPARAMETERSDEFAULTS_H\n")
+    file(GENERATE OUTPUT "${OUT_HEADER}" CONTENT "${TMP_HEADER}")
     message(STATUS "Generated ${OUT_HEADER}")
     add_custom_target(GPU_PARAM_HEADER_${GPU_ARCH}_ALL ALL DEPENDS ${OUT_HEADER} ${CMAKE_CURRENT_SOURCE_DIR}/cmake/gpu_param_header_generator.cmake ${GPU_PARAM_JSON})
-endfunction()
\ No newline at end of file
+endfunction()