diff --git a/scripts/cmake/uuid-registry.cmake b/scripts/cmake/uuid-registry.cmake
index 80b6310d1be8..0d3b287a7d62 100644
--- a/scripts/cmake/uuid-registry.cmake
+++ b/scripts/cmake/uuid-registry.cmake
@@ -5,8 +5,8 @@
 # Simple target.  FOUR (really 4.5, as LIBRARY builds use the same
 # CMakeLists.txt but differ significantly in how it executes)
 # different cmake environments into which it needs to build.
-is_zephyr(zephyr_is)
-if(zephyr_is)
+is_zephyr(zephyr)
+if(zephyr)
   set(TOPDIR ${sof_top_dir})
   set(UUID_REG_H ${PROJECT_BINARY_DIR}/include/generated/uuid-registry.h)
   set(DEP_TARGET zephyr_interface)
diff --git a/src/audio/CMakeLists.txt b/src/audio/CMakeLists.txt
index 0a4a78d53ca8..c7f45ca88bc8 100644
--- a/src/audio/CMakeLists.txt
+++ b/src/audio/CMakeLists.txt
@@ -131,19 +131,17 @@ sof_list_append_ifdef(CONFIG_COMP_BLOB base_files data_blob.c)
 
 ### (end of common files)
 
-is_zephyr(it_is)
-if(it_is) ###  Zephyr ###
+is_zephyr(zephyr)
+if(zephyr) ###  Zephyr ###
 
 	zephyr_library_sources(
 		${base_files}
 	)
 
 	return()
-endif()
-
-### XTOS normal build (not shared library) ###
+elseif(NOT CONFIG_COMP_MODULE_SHARED_LIBRARY_BUILD)
+	### not shared library, e.g. testbench ###
 
-if(NOT CONFIG_COMP_MODULE_SHARED_LIBRARY_BUILD)
 	add_local_sources(sof
 		host-legacy.c
 		${base_files}
diff --git a/src/audio/codec/CMakeLists.txt b/src/audio/codec/CMakeLists.txt
index bdef3031ceb5..3a81324633e5 100644
--- a/src/audio/codec/CMakeLists.txt
+++ b/src/audio/codec/CMakeLists.txt
@@ -19,18 +19,3 @@ if(zephyr) ###  Zephyr ###
 
   return()
 endif()
-
-### XTOS ###
-if(CONFIG_DTS_CODEC)
-  add_local_sources(sof dts/dts.c)
-  target_compile_definitions(sof PRIVATE -DDTS_MATH_INT32 -DDTS_XTENSA)
-
-  if (CONFIG_DTS_CODEC_STUB)
-    add_local_sources(sof dts/dts_stub.c)
-  else()
-    sof_add_static_library(DtsCodec
-      ${SOF_ROOT_SOURCE_DIRECTORY}/third_party/lib/libdts-sof-interface-i32.a)
-    target_include_directories(sof PRIVATE ${CMAKE_SOURCE_DIR}/third_party/include)
-  endif()
-
-endif()
diff --git a/src/audio/google/CMakeLists.txt b/src/audio/google/CMakeLists.txt
index d4d89ec8778a..fcb829306e16 100644
--- a/src/audio/google/CMakeLists.txt
+++ b/src/audio/google/CMakeLists.txt
@@ -65,8 +65,8 @@ if(zephyr) ###  Zephyr ###
 	return()
 endif()
 
-### XTOS build rules ###
-if((NOT CONFIG_LIBRARY) OR CONFIG_LIBRARY_STATIC)
+### Library build rules ###
+if(CONFIG_LIBRARY_STATIC)
 	if(CONFIG_COMP_GOOGLE_HOTWORD_DETECT)
 		add_local_sources(sof
 			google_hotword_detect.c
diff --git a/src/audio/rtnr/CMakeLists.txt b/src/audio/rtnr/CMakeLists.txt
index 034bd339a9ae..26ee76ac38f8 100644
--- a/src/audio/rtnr/CMakeLists.txt
+++ b/src/audio/rtnr/CMakeLists.txt
@@ -12,15 +12,11 @@ if(zephyr) ###  Zephyr ###
   zephyr_library_sources(rtnr.c)
   zephyr_library_sources_ifdef(CONFIG_COMP_RTNR_STUB rtnr_stub.c)
 
-else() ### XTOS ###
+else() ### library, e.g. testbench or plugin ###
 
   add_local_sources(sof rtnr.c)
   if (CONFIG_COMP_RTNR_STUB)
     add_local_sources(sof rtnr_stub.c)
-  elseif(CONFIG_TIGERLAKE)
-    add_subdirectory(rtklib/tgl)
-  elseif(CONFIG_MT8195)
-    add_subdirectory(rtklib/mt8195)
   endif()
 
 endif()
diff --git a/src/audio/smart_amp/CMakeLists.txt b/src/audio/smart_amp/CMakeLists.txt
index 22d23b2820f9..cb4eac564634 100644
--- a/src/audio/smart_amp/CMakeLists.txt
+++ b/src/audio/smart_amp/CMakeLists.txt
@@ -22,14 +22,4 @@ if(zephyr) ###  Zephyr ###
     zephyr_include_directories(CONFIG_MAXIM_DSM ${CMAKE_CURRENT_LIST_DIR}/include/dsm_api/inc/)
   endif()
 
-else() ### XTOS
-
-  if(CONFIG_MAXIM_DSM)
-    if(NOT CONFIG_MAXIM_DSM_STUB)
-      sof_add_static_library(dsm ${CMAKE_CURRENT_LIST_DIR}/lib/release/dsm_lib/libdsm.a)
-    endif()
-
-    target_include_directories(sof PUBLIC ${CMAKE_CURRENT_LIST_DIR}/include/dsm_api/inc)
-  endif()
-
 endif()
diff --git a/src/audio/src/CMakeLists.txt b/src/audio/src/CMakeLists.txt
index aab97633a2c1..469384694379 100644
--- a/src/audio/src/CMakeLists.txt
+++ b/src/audio/src/CMakeLists.txt
@@ -10,8 +10,8 @@ endif()
 
 sof_list_append_ifdef(CONFIG_COMP_SRC_LITE base_files src_lite.c)
 
-is_zephyr(it_is)
-if(it_is) ###  Zephyr ###
+is_zephyr(zephyr)
+if(zephyr) ###  Zephyr ###
 
   if(CONFIG_COMP_SRC STREQUAL "m")
 
@@ -24,7 +24,7 @@ if(it_is) ###  Zephyr ###
 
   endif()
 
-else() ### XTOS ###
+else() ### library, e.g. testbench or plugin ###
 
   add_local_sources(sof ${base_files})
 
diff --git a/src/debug/CMakeLists.txt b/src/debug/CMakeLists.txt
index 3025cb8919f5..5cb8e8bd9c6c 100644
--- a/src/debug/CMakeLists.txt
+++ b/src/debug/CMakeLists.txt
@@ -6,16 +6,12 @@ endif()
 
 add_subdirectory(tester)
 
-is_zephyr(it_is)
-if(it_is) ###  Zephyr ###
+is_zephyr(zephyr)
+if(zephyr) ###  Zephyr ###
 
 add_subdirectory(debug_stream)
 add_subdirectory(telemetry)
 
 zephyr_library_sources_ifdef(CONFIG_COLD_STORE_EXECUTE_DEBUG dram.c)
 
-else() ###  Not Zephyr ###
-
-add_local_sources(sof panic.c)
-
 endif() # Zephyr
diff --git a/src/debug/tester/CMakeLists.txt b/src/debug/tester/CMakeLists.txt
index 2220c5b773b8..714f379a4966 100644
--- a/src/debug/tester/CMakeLists.txt
+++ b/src/debug/tester/CMakeLists.txt
@@ -6,8 +6,8 @@ set(base_files
   tester_simple_dram_test.c
 )
 
-is_zephyr(it_is)
-if(it_is) ###  Zephyr ###
+is_zephyr(zephyr)
+if(zephyr) ###  Zephyr ###
 
   if(CONFIG_COMP_TESTER STREQUAL "m")
 
@@ -20,10 +20,4 @@ if(it_is) ###  Zephyr ###
 
   endif()
 
-else() ### XTOS ###
-
-  if(CONFIG_COMP_TESTER)
-    add_local_sources(sof ${base_files})
-  endif()
-
 endif()
diff --git a/src/idc/CMakeLists.txt b/src/idc/CMakeLists.txt
index 26a47bd50d62..1cedc1f739f4 100644
--- a/src/idc/CMakeLists.txt
+++ b/src/idc/CMakeLists.txt
@@ -4,6 +4,4 @@ is_zephyr(zephyr)
 if(zephyr)
   add_local_sources_ifdef(CONFIG_SMP sof idc.c)
   add_local_sources(sof zephyr_idc.c)
-else()
-  add_local_sources(sof idc.c)
 endif()
diff --git a/src/init/CMakeLists.txt b/src/init/CMakeLists.txt
index efa155793621..5bf15761fa29 100644
--- a/src/init/CMakeLists.txt
+++ b/src/init/CMakeLists.txt
@@ -1,39 +1,11 @@
 # SPDX-License-Identifier: BSD-3-Clause
 
-is_zephyr(it_is)
-if(it_is)  ### Zephyr ###
-
+is_zephyr(zephyr)
+if(zephyr)  ### Zephyr ###
 
 zephyr_library_sources(
 	init.c
 	ext_manifest.c
 )
 
-
-else()  ### Not Zephyr ###
-
-
-add_local_sources(sof init.c)
-
-add_library(ext_manifest STATIC "")
-
-# define compiler version
-set_property(TARGET ext_manifest APPEND
-	PROPERTY COMPILE_DEFINITIONS
-	XCC_TOOLS_VERSION="${XCC_TOOLS_VERSION}")
-
-# and optimization settings
-get_optimization_flag(optimization_flag)
-set_property(TARGET ext_manifest APPEND
-	PROPERTY COMPILE_DEFINITIONS
-	CC_OPTIMIZE_FLAGS="-${optimization_flag}")
-
-add_local_sources(ext_manifest
-	ext_manifest.c)
-sof_append_relative_path_definitions(ext_manifest)
-
-target_link_libraries(ext_manifest sof_options)
-target_link_libraries(sof_static_libraries INTERFACE ext_manifest)
-
-
 endif() # Zephyr
diff --git a/src/ipc/CMakeLists.txt b/src/ipc/CMakeLists.txt
index 5639c2fe7df6..15fab54b3c30 100644
--- a/src/ipc/CMakeLists.txt
+++ b/src/ipc/CMakeLists.txt
@@ -13,8 +13,8 @@ add_local_sources(sof
 	notification_pool.c
 )
 
-is_zephyr(it_is)
-if(it_is) ###  Zephyr ###
+is_zephyr(zephyr)
+if(zephyr) ###  Zephyr ###
 
 # dma-copy only used for dma-trace
 zephyr_library_sources_ifdef(CONFIG_TRACE dma-copy.c)
@@ -25,18 +25,11 @@ if (CONFIG_SOC_SERIES_INTEL_CAVS_V25 OR CONFIG_SOC_SERIES_INTEL_ADSP_ACE)
 	)
 endif()
 
-
 else() ###  Not Zephyr ###
 
-
 if (CONFIG_TRACE)
 	add_local_sources(sof
 		dma-copy.c)
 endif()
 
-if (CONFIG_LIBRARY)
-	return()
-endif()
-
-
 endif() # Zephyr
diff --git a/src/ipc/ipc3/CMakeLists.txt b/src/ipc/ipc3/CMakeLists.txt
index db1e6825085c..02a2d337c53d 100644
--- a/src/ipc/ipc3/CMakeLists.txt
+++ b/src/ipc/ipc3/CMakeLists.txt
@@ -7,18 +7,11 @@ add_local_sources(sof
 		dai.c
 )
 
-is_zephyr(it_is)
-if(it_is) ###  Zephyr ###
+is_zephyr(zephyr)
+if(zephyr) ###  Zephyr ###
 
 zephyr_library_sources(
 	host-page-table.c
 )
 
-else()  ### Not Zephyr ###
-
-if (CONFIG_HOST_PTABLE)
-	add_local_sources(sof
-		host-page-table.c)
-endif()
-
 endif() # Zephyr
diff --git a/src/ipc/ipc4/CMakeLists.txt b/src/ipc/ipc4/CMakeLists.txt
index 5a4d271e7f13..02c56130ed11 100644
--- a/src/ipc/ipc4/CMakeLists.txt
+++ b/src/ipc/ipc4/CMakeLists.txt
@@ -9,23 +9,15 @@ add_local_sources(sof
 	notification.c
 )
 
-
-is_zephyr(it_is)
-if(it_is) ###  Zephyr ###
+is_zephyr(zephyr)
+if(zephyr) ###  Zephyr ###
 
 zephyr_library_sources_ifdef(CONFIG_AMS
 	ams_helpers.c
 )
 
-
 else()  ### Not Zephyr ####
 
-
-add_local_sources(sof
-	ams_helpers.c
-)
-
 target_include_directories(sof_options INTERFACE ${RIMAGE_TOP}/src/include)
 
-
 endif() # Zephyr
diff --git a/src/lib/CMakeLists.txt b/src/lib/CMakeLists.txt
index 631731675e5f..f7a37d50cd72 100644
--- a/src/lib/CMakeLists.txt
+++ b/src/lib/CMakeLists.txt
@@ -32,15 +32,4 @@ if(zephyr) ###  Zephyr ###
     add_local_sources(sof clk.c)
   endif()
 
-else() ### XTOS ###
-
-  add_local_sources(sof
-    ${common_files}
-    lib.c
-    alloc.c
-    pm_runtime.c
-    clk.c
-    wait.c
-    )
-
 endif()
diff --git a/src/math/CMakeLists.txt b/src/math/CMakeLists.txt
index 047c4c2d510b..44a42884455d 100644
--- a/src/math/CMakeLists.txt
+++ b/src/math/CMakeLists.txt
@@ -91,14 +91,14 @@ if(CONFIG_MATH_MU_LAW_CODEC)
   list(APPEND base_files mu_law.c)
 endif()
 
-is_zephyr(it_is)
-if(it_is) ###  Zephyr ###
+is_zephyr(zephyr)
+if(zephyr) ###  Zephyr ###
 
   zephyr_library_sources(
     ${base_files}
   )
 
-else() ### XTOS ###
+else() ### library, e.g. testbench or plugin ###
 
   add_local_sources(sof ${base_files})
 
diff --git a/src/math/auditory/CMakeLists.txt b/src/math/auditory/CMakeLists.txt
index ac89bc544f48..b24cf968f237 100644
--- a/src/math/auditory/CMakeLists.txt
+++ b/src/math/auditory/CMakeLists.txt
@@ -10,14 +10,14 @@ if(CONFIG_MATH_32BIT_MEL_FILTERBANK)
   list(APPEND base_files mel_filterbank_32.c)
 endif()
 
-is_zephyr(it_is)
-if(it_is) ###  Zephyr ###
+is_zephyr(zephyr)
+if(zephyr) ###  Zephyr ###
 
   zephyr_library_sources(
     ${base_files}
   )
 
-else() ### XTOS ###
+else() ### library, e.g. testbench or plugin ###
 
   add_local_sources(sof ${base_files})
 
diff --git a/src/math/fft/CMakeLists.txt b/src/math/fft/CMakeLists.txt
index cfdf61b2bd8a..82b8aee77b4d 100644
--- a/src/math/fft/CMakeLists.txt
+++ b/src/math/fft/CMakeLists.txt
@@ -10,14 +10,14 @@ if(CONFIG_MATH_32BIT_FFT)
   list(APPEND base_files fft_32.c fft_32_hifi3.c)
 endif()
 
-is_zephyr(it_is)
-if(it_is) ###  Zephyr ###
+is_zephyr(zephyr)
+if(zephyr) ###  Zephyr ###
 
   zephyr_library_sources(
     ${base_files}
   )
 
-else() ### XTOS ###
+else() ### library, e.g. testbench or plugin ###
 
   add_local_sources(sof ${base_files})
 
diff --git a/src/schedule/CMakeLists.txt b/src/schedule/CMakeLists.txt
index 7646a55191ba..afa1cdc95324 100644
--- a/src/schedule/CMakeLists.txt
+++ b/src/schedule/CMakeLists.txt
@@ -12,8 +12,8 @@ if(CONFIG_SCHEDULE_DMA_SINGLE_CHANNEL AND NOT(CONFIG_DMA_DOMAIN))
 	list(APPEND base_files dma_single_chan_domain.c)
 endif()
 
-is_zephyr(it_is)
-if(it_is) ###  Zephyr ###
+is_zephyr(zephyr)
+if(zephyr) ###  Zephyr ###
 
 zephyr_library_sources(
 	${base_files}
@@ -46,14 +46,4 @@ zephyr_library_sources_ifdef(CONFIG_ZEPHYR_TWB_SCHEDULER
 	zephyr_twb_schedule.c
 )
 
-else() ###  Not Zephyr ###
-
-add_local_sources(sof
-	${base_files}
-	edf_schedule.c
-	ll_schedule.c
-	task.c
-	timer_domain.c
-)
-
 endif()