separate source into kernel/ user/ mkfs/

kernel/kernel.ld

@@ -0,0 +1,31 @@
+OUTPUT_ARCH( "riscv" )
+ENTRY( _entry )
+
+SECTIONS
+{
+  /*
+   * ensure that entry.S / _entry is at 0x80000000,
+   * where qemu's -kernel jumps.
+   */
+  . = 0x80000000;
+  .text :
+  {
+    *(.text)
+    . = ALIGN(0x1000);
+    *(trampoline)
+  }
+
+  . = ALIGN(0x1000);
+  PROVIDE(etext = .);
+
+  /*
+   * make sure end is after data and bss.
+   */
+  .data : {
+    *(.data)
+  }
+  bss : {
+    *(.bss)
+    PROVIDE(end = .);
+  }
+}