feat: add RISC-V QEMU demo support and fix assembly implementation

Author: Winstonllllai

CMakeLists.txt

@@ -69,4 +69,33 @@ set(CPACK_SOURCE_IGNORE_FILES
   ".*~$"
 )
 set(CPACK_VERBATIM_VARIABLES YES)
-include(CPack)
+include(CPack)
+
+# Enable the QEMU Virt demo application (Target: kernel.elf)
+set(QEMU_DEMO_DIR ${CMAKE_CURRENT_LIST_DIR}/ports/risc-v32/gnu/example_build/qemu_virt)
+
+add_executable(kernel.elf 
+    ${QEMU_DEMO_DIR}/demo_threadx.c
+    ${QEMU_DEMO_DIR}/entry.s
+    ${QEMU_DEMO_DIR}/uart.c
+    ${QEMU_DEMO_DIR}/plic.c
+    ${QEMU_DEMO_DIR}/hwtimer.c
+    ${QEMU_DEMO_DIR}/trap.c
+    ${QEMU_DEMO_DIR}/board.c
+    ${QEMU_DEMO_DIR}/tx_initialize_low_level.S
+)
+
+target_link_libraries(kernel.elf PRIVATE threadx)
+
+target_include_directories(kernel.elf PRIVATE 
+    ${CMAKE_CURRENT_LIST_DIR}/common/inc 
+    ${CMAKE_CURRENT_LIST_DIR}/ports/${THREADX_ARCH}/${THREADX_TOOLCHAIN}/inc
+    ${QEMU_DEMO_DIR}
+)
+
+# Linker options
+target_link_options(kernel.elf PRIVATE 
+    -T${QEMU_DEMO_DIR}/link.lds 
+    -nostartfiles
+    -Wl,-Map=kernel.map
+)

ports/risc-v32/gnu/example_build/qemu_virt/entry.s

@@ -1,5 +1,5 @@
 
-.section .text
+.section .init
 .align 4
 .global _start
 .extern main

ports/risc-v32/gnu/example_build/qemu_virt/link.lds

@@ -8,6 +8,10 @@ SECTIONS
    * where qemu's -kernel jumps.
    */
   . = 0x80000000;
+  
+  .init : {
+    KEEP (*(.init))
+  }
 
   .text : {
     *(.text .text.*)