Add first user program hello_world.rs

user/src/linker.ld

@@ -0,0 +1,26 @@
+OUTPUT_ARCH(riscv)
+ENTRY(_start)
+
+BASE_ADDRESS = 0x80040000;
+
+SECTIONS
+{
+    . = BASE_ADDRESS;
+    .text : {
+        *(.text.entry)
+        *(.text .text.*)
+    }
+    .rodata : {
+        *(.rodata .rodata.*)
+    }
+    .data : {
+        *(.data .data.*)
+    }
+    .bss : {
+        *(.bss .bss.*)
+    }
+    /DISCARD/ : {
+        *(.eh_frame)
+        *(.debug*)
+    }
+}