--- /dev/null
+
+/* Segment indexes. Must match the gdt definition in segment.c. */
+enum {
+ NULL_SEG,
+ FLAT_CODE,
+ FLAT_DATA,
+ RELOC_CODE,
+ RELOC_DATA,
+ NUM_SEG,
+};
+
+/* Values for segment selector register */
+#define FLAT_CS (FLAT_CODE << 3)
+#define FLAT_DS (FLAT_DATA << 3)
+#define RELOC_CS (RELOC_CODE << 3)
+#define RELOC_DS (RELOC_DATA << 3)
+
+/* i386 segment descriptor */
+struct segment_desc {
+ unsigned short limit_0;
+ unsigned short base_0;
+ unsigned char base_16;
+ unsigned char types;
+ unsigned char flags;
+ unsigned char base_24;
+};
+
+extern struct segment_desc gdt[NUM_SEG];
+
+#define GDT_LIMIT ((NUM_SEG << 3) - 1)