*===========================================================================*/
/* Major device numbers. */
-#define NONE_MAJOR 0 /* 0 = not used */
+
+/* Note that NO_DEV is major 0, minor 0, and means "no device". In contrast,
+ * NONE_MAJOR is used for file systems that do not have backing device (but are
+ * mounted on device 'none'). For administrative purposes, these file systems
+ * need to be assigned a pseudo device, and such pseudo devices are allocated
+ * with major number NONE_MAJOR. Because of NO_DEV, the NONE_MAJOR devices
+ * start from minor number 1. Otherwise, NONE_MAJOR is completely independent
+ * from NO_DEV, and it should be possible to set NONE_MAJOR to a nonzero value!
+ */
+#define NONE_MAJOR 0 /* 0 = pseudo device for 'none' FSes */
#define MEMORY_MAJOR 1 /* 1 = /dev/mem (memory devices) */
#define FLOPPY_MAJOR 2 /* 2 = /dev/fd0 (floppy disks) */
/* 3 = /dev/c0 */