Fixes and improvements (#642)

Buildscripts/TactilitySDK/TactilitySDK.cmake

@@ -7,6 +7,18 @@ endfunction()
 macro(tactility_project project_name)
     set(TACTILITY_SKIP_SPIFFS 1)
 
+    # Tactility's PanicHandler.cpp needs s0 to stay a frame pointer to capture a callstack for
+    # a RISC-V app's crashes, which GCC does not guarantee without this flag. The firmware sets the
+    # same flag for its own code, but a crash usually happens in app code, built separately here.
+    # Gated to RISC-V since Xtensa never reads s0 this way. idf_build_set_property(), not
+    # add_compile_options(): the app's code compiles as an idf_component_register() component
+    # (Apps/*/main/CMakeLists.txt), which reads ESP-IDF's own COMPILE_OPTIONS build property rather
+    # than plain directory-scoped flags. project_elf() below uses the same property for its own
+    # flags for the same reason.
+    if(CONFIG_IDF_TARGET_ARCH_RISCV)
+        idf_build_set_property(COMPILE_OPTIONS "-fno-omit-frame-pointer" APPEND)
+    endif()
+
     include("${TACTILITY_SDK_PATH}/Libraries/elf_loader/elf_loader.cmake")
     project_elf($project_name)