Intel ITANIUM ARCHITECTURE - SOFTWARE DEVELOPERS MANUAL VOLUME 1 REV 2.3 Manual page 1537

IRET/IRETD—Interrupt Return (Continued)
(* Resume execution in Virtual 8086 mode *)
END;
TASK-RETURN: (* PE=1, VM=1, NT=1 *)
Read segment selector in link field of current TSS;
IF local/global bit is set to local
OR index not within GDT limits
FI;
Access TSS for task specified in link field of current TSS;
IF TSS descriptor type is not TSS or if the TSS is marked not busy
THEN #GP(TSS selector);
FI;
IF TSS not present
THEN #NP(TSS selector);
FI;
SWITCH-TASKS (without nesting) to TSS specified in link field of current TSS;
Mark the task just abandoned as NOT BUSY;
IF EIP is not within code segment limit
THEN #GP(0);
FI;
END;
PROTECTED-MODE-RETURN: (* PE=1, VM=0 in flags image *)
IF return code segment selector is null THEN GP(0); FI;
IF return code segment selector addrsses descriptor beyond descriptor table limit
THEN GP(selector; FI;
Read segment descriptor pointed to by the return code segment selector
IF return code segment descriptor is not a code segment THEN #GP(selector); FI;
IF return code segment selector RPL < CPL THEN #GP(selector); FI;
IF return code segment descriptor is conforming
AND return code segment DPL > return code segment selector RPL
IF return code segment descriptor is not present THEN #NP(selector); FI:
IF return code segment selector RPL > CPL
THEN GOTO RETURN-OUTER-PRIVILEGE-LEVEL;
ELSE GOTO RETURN-TO-SAME-PRIVILEGE-LEVEL
FI;
END;
RETURN-TO-SAME-PRIVILEGE-LEVEL: (* PE=1, VM=0 in flags image, RPL=CPL *)
IF EIP is not within code segment limits THEN #GP(0); FI;
EIP  tempEIP;
CS  tempCS; (* segment descriptor information also loaded *)
EFLAGS (CF, PF, AF, ZF, SF, TF, DF, OF, NT)  tempEFLAGS;
IF OperandSize=32
THEN
FI;
IF CPL  IOPL
THEN
FI;
Volume 4: Base IA-32 Instruction Reference
THEN #GP(TSS selector);
THEN #GP(selector); FI;
EFLAGS(RF, AC, ID)  tempEFLAGS;
EFLAGS(IF)  tempEFLAGS;
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