Hello, for curiosity is there any specific reason for put values in the first entry of GDT in the file src/cpu/i386/entry[16|32].inc ?. The content of the first entry is: .globl EXT(gdtptr) gdt: EXT(gdtptr): .word gdt_end - gdt -1 /* compute the table limit */ .long gdt /* we know the offset */ .word 0 ... etc ... Xavi. Regards.