The art of Linux kernel design learn notes (iv) default and offset registers

　　reference book:"Intel microprocessors"

　　Table 1 Default 16-bit segment + offset addressing combination

Paragraph	Offset amount	Special purpose
Cs	Ip	Instruction Address
Ss	SP or BP	Stack Address
Ds	BX, DI, SI, 8-bit or 16-digit	Data address
Es	Di for string instructions	String Destination Address

Table 2 default 32-bit segment + offset addressing combination

Paragraph	Offset amount	Special purpose
Cs	Eip	Instruction Address
Ss	ESP or EBP	Stack Address
Ds	EAX, EBX, ECX, EDX, ESI, EDI, one 8-bit or 32-digit	Data address
Es	EDI for string instructions	String Destination Address
Fs	No default value	General Address
Gs	No default value	General Address

　　SEG Command:

　　The SEG directive changes the segment register in the default "segment + Offset addressing combination".

SEG CS MOV sectors, CX MOV AX, #INITSEG

SEG will only affect MOV sectors, CX (equivalent to mov cs:[sectors], CX) without affecting mov AX, #INITSEG.

The art of Linux kernel design learn notes (iv) default and offset registers