sys/kern: Add VFS support

- Refactor the libio interface

- Move syscalls into an rtemsbsd location

- Provide a root directory mount point

Update #4475

rtemsbsd/include/vm/vm_object.h

@@ -1 +1,16 @@
-/* EMPTY */
+#ifndef RTEMS_VM_OBJCT_H
+#define RTEMS_VM_OBJCT_H
+
+/*
+ * Helpers to perform conversion between vm_object page indexes and offsets.
+ * IDX_TO_OFF() converts an index into an offset.
+ * OFF_TO_IDX() converts an offset into an index.
+ * OBJ_MAX_SIZE specifies the maximum page index corresponding to the
+ *   maximum unsigned offset.
+ */
+#define IDX_TO_OFF(idx) (((vm_ooffset_t)(idx)) << PAGE_SHIFT)
+#define OFF_TO_IDX(off) ((vm_pindex_t)(((vm_ooffset_t)(off)) >> PAGE_SHIFT))
+#define UOFF_TO_IDX(off) OFF_TO_IDX(off)
+#define OBJ_MAX_SIZE    (OFF_TO_IDX(UINT64_MAX) + 1)
+
+#endif