-#ifndef HEADER_LOADER_H
-#define HEADER_LOADER_H
+#ifndef THREADS_LOADER_H
+#define THREADS_LOADER_H
/* Constants fixed by the PC BIOS. */
#define LOADER_BASE 0x7c00 /* Physical address of loader's base. */
-#define LOADER_SIZE 0x200 /* Loader size in bytes (one disk sector). */
+#define LOADER_END 0x7e00 /* Physical address of end of loader. */
/* Physical address of kernel base. */
#define LOADER_KERN_BASE 0x100000 /* 1 MB. */
#define LOADER_PHYS_BASE 0xc0000000 /* 3 GB. */
/* Offsets within the loader. */
-#define LOADER_BIOS_SIG (LOADER_SIZE - 2) /* aa55 BIOS signature. */
-#define LOADER_CMD_LINE (LOADER_BIOS_SIG - 0x80) /* Kernel command line. */
-#define LOADER_RAM_PAGES (LOADER_CMD_LINE - 4) /* # of pages of RAM. */
+#define LOADER_BIOS_SIG (LOADER_END - 2) /* 0xaa55 BIOS signature. */
+#define LOADER_CMD_LINE_LEN 0x80 /* Command line length. */
+#define LOADER_CMD_LINE (LOADER_BIOS_SIG - LOADER_CMD_LINE_LEN)
+ /* Kernel command line. */
+#define LOADER_RAM_PAGES (LOADER_CMD_LINE - 4) /* # of pages of RAM. */
-#endif /* loader.h */
+/* GDT selectors defined by loader.
+ More selectors are defined by userprog/gdt.h. */
+#define SEL_NULL 0x00 /* Null selector. */
+#define SEL_KCSEG 0x08 /* Kernel code selector. */
+#define SEL_KDSEG 0x10 /* Kernel data selector. */
+
+#endif /* threads/loader.h */