Jason Wang (@stuha) started discussion #101
To react on interrupt CPU uses special structure - Interrupt Descriptor Table or IDT. IDT is an array of 8-byte descriptors like Global Descriptor Table, but IDT entries are called gates. CPU multiplies vector number on 8 to find index of the IDT entry. But in 64-bit mode IDT is an array of 16-byte descriptors and CPU multiplies vector number on 16 to find index of the entry in the IDT. We remember from the previous part that CPU uses special GDTR register to locate Global Descriptor Table, so CPU uses special register IDTR for Interrupt Descriptor Table and lidt instruction for loading base address of the table into this register.