diff --git a/cmake/Zephyr-sdkConfig.cmake b/cmake/Zephyr-sdkConfig.cmake
index e9662d5e..8104c43f 100644
--- a/cmake/Zephyr-sdkConfig.cmake
+++ b/cmake/Zephyr-sdkConfig.cmake
@@ -13,7 +13,11 @@ get_filename_component(ZEPHYR_SDK_INSTALL_DIR ${CMAKE_CURRENT_LIST_DIR}/.. ABSOL
 set(ZEPHYR_SDK_INSTALL_DIR ${ZEPHYR_SDK_INSTALL_DIR})
 
 if(NOT DEFINED ZEPHYR_TOOLCHAIN_VARIANT)
-  set(ZEPHYR_TOOLCHAIN_VARIANT "zephyr/gnu")
+  if(DEFINED ZEPHYR_TOOLCHAIN_VARIANT_COMPILER_SUPPORT)
+    set(ZEPHYR_TOOLCHAIN_VARIANT "zephyr/gnu")
+  else()
+    set(ZEPHYR_TOOLCHAIN_VARIANT "zephyr")
+  endif()
 endif()
 
 # Those are CMake package parameters.
diff --git a/cmake/zephyr/Kconfig b/cmake/zephyr/Kconfig
index 96db3576..16341bf2 100644
--- a/cmake/zephyr/Kconfig
+++ b/cmake/zephyr/Kconfig
@@ -24,7 +24,6 @@ config PICOLIBC_DEFAULT
 	  Zephyr SDK >=0.17.1 always uses Picolibc
 
 # libstdc++ is built without exception support in -Os mode
-# gcc 14.3 has bugs compiling with -Os on riscv
 choice COMPILER_OPTIMIZATIONS
-	default SPEED_OPTIMIZATIONS if ("$(TOOLCHAIN_VARIANT_COMPILER)" = "gnu") && CPP_EXCEPTIONS
+	default SPEED_OPTIMIZATIONS if ("$(TOOLCHAIN_VARIANT_COMPILER)" != "llvm") && CPP_EXCEPTIONS
 endchoice
diff --git a/scripts/template_setup_posix b/scripts/template_setup_posix
index d680bf85..036e27d0 100644
--- a/scripts/template_setup_posix
+++ b/scripts/template_setup_posix
@@ -69,6 +69,7 @@ usage()
   echo "     all               Install all GNU toolchains"
   echo "  -l                   Install LLVM toolchain"
   echo "  -h                   Install host tools"
+  echo "  -o                   Create symbolic links matching the old SDK layout for old Zephyr (< 4.3) bisectability"
   echo "  -c                   Register Zephyr SDK CMake package"
   echo
   echo "Supported GNU Toolchains:"
@@ -117,6 +118,8 @@ user_prompt()
   # Environment Configurations
   ask_yn "Register Zephyr SDK CMake package" && do_cmake_pkg="y"
 
+  ask_yn "Create symbolic links for old Zephyr bisectability" && do_old_zephyr="y"
+
   echo
 }
 
@@ -159,6 +162,9 @@ else
       -c)
         do_cmake_pkg="y"
         ;;
+      -o)
+	do_old_zephyr="y"
+	;;
       '-?')
         usage
         exit 0
@@ -301,6 +307,15 @@ if [ "${do_cmake_pkg}" = "y" ]; then
   echo
 fi
 
+# Create links for old Zephyr versions
+if [ "${do_old_zephyr}" = "y" ]; then
+  echo "Creating links for old Zephyr bisectability ..."
+  ln -sr gnu/* . || assert_rc "ERROR: Creating toolchain links" 50
+  ln -sr cmake/zephyr/gnu/* cmake/zephyr || assert_rc "ERROR: Creating cmake links" 50
+  ln -sr hosttools/* . || assert_rc "ERROR: Creating hosttools links" 50
+  echo
+fi
+
 echo "All done."
 if [ "${interactive}" = "y" ]; then
   read -n 1 -s -r -p "Press any key to exit ..."