POPF/POPFD -- Pop Stack into FLAGS or EFLAGS Register

Opcode   Instruction   Clocks   Description

9D       POPF          5        Pop top of stack FLAGS
9D       POPFD         5        Pop top of stack into EFLAGS

Operation

Flags := Pop();

Description

POPF/POPFD pops the word or doubleword on the top of the stack and stores the value in the flags register. If the operand-size attribute of the instruction is 16 bits, then a word is popped and the value is stored in FLAGS. If the operand-size attribute is 32 bits, then a doubleword is popped and the value is stored in EFLAGS.

Refer to Chapter 2 and Chapter 4 for information about the FLAGS and EFLAGS registers. Note that bits 16 and 17 of EFLAGS, called VM and RF, respectively, are not affected by POPF or POPFD.

The I/O privilege level is altered only when executing at privilege level 0. The interrupt flag is altered only when executing at a level at least as privileged as the I/O privilege level. (Real-address mode is equivalent to privilege level 0.) If a POPF instruction is executed with insufficient privilege, an exception does not occur, but the privileged bits do not change.

Flags Affected

All flags except VM and RF

Protected Mode Exceptions

#SS(0) if the top of stack is not within the stack segment

Real Address Mode Exceptions

Interrupt 13 if any part of the operand would lie outside of the effective address space from 0 to 0FFFFH

Virtual 8086 Mode Exceptions

#GP(0) fault if IOPL is less than 3, to permit emulation

up: Chapter 17 -- 80386 Instruction Set
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