+static const char *const if_name[IF_COUNT] = {
+ [IF_NONE] = "none",
+ [IF_IDE] = "ide",
+ [IF_SCSI] = "scsi",
+ [IF_FLOPPY] = "floppy",
+ [IF_PFLASH] = "pflash",
+ [IF_MTD] = "mtd",
+ [IF_SD] = "sd",
+ [IF_VIRTIO] = "virtio",
+ [IF_XEN] = "xen",
+};
+
+static const int if_max_devs[IF_COUNT] = {
+ /*
+ * Do not change these numbers! They govern how drive option
+ * index maps to unit and bus. That mapping is ABI.
+ *
+ * All controllers used to imlement if=T drives need to support
+ * if_max_devs[T] units, for any T with if_max_devs[T] != 0.
+ * Otherwise, some index values map to "impossible" bus, unit
+ * values.
+ *
+ * For instance, if you change [IF_SCSI] to 255, -drive
+ * if=scsi,index=12 no longer means bus=1,unit=5, but
+ * bus=0,unit=12. With an lsi53c895a controller (7 units max),
+ * the drive can't be set up. Regression.
+ */
+ [IF_IDE] = 2,
+ [IF_SCSI] = 7,
+};
+