Intel ITANIUM ARCHITECTURE - SOFTWARE DEVELOPERS MANUAL VOLUME 1 REV 2.3 Manual page 1522

INTn/INTO/INT3—Call to Interrupt Procedure (Continued)
IF TSS not present
FI;
SWITCH-TASKS (with nesting) to TSS;
IF interrupt caused by fault with error code
THEN
FI;
IF EIP not within code segment limit
THEN #GP(0);
FI;
END;
TRAP-OR-INTERRUPT-GATE
Read segment selector for trap or interrupt gate (IDT descriptor);
IF segment selector for code segment is null
THEN #GP(0H + EXT); (* null selector with EXT flag set *)
FI;
IF segment selector is not within its descriptor table limits
THEN #GP(selector + EXT);
FI;
Read trap or interrupt handler descriptor;
IF descriptor does not indicate a code segment
OR code segment descriptor DPL CPL
FI;
IF trap or interrupt gate segment is not present,
THEN #NP(selector + EXT);
FI;
IF code segment is non-conforming AND DPL  CPL
THEN IF VM=0
FI;
ELSE (* PE=1, interrupt or trap gate, DPL  CPL *)
4:220
THEN #NP(TSS selector);
IF stack limit does not allow push of two bytes
THEN #SS(0);
FI;
Push(error code);
THEN #GP(selector + EXT);
THEN
GOTO INTER-PRIVILEGE-LEVEL-INTERRUPT;
(* PE=1, interrupt or trap gate, nonconforming *)
(* code segment, DPLCPL, VM=0 *)
ELSE (* VM=1 *)
IF code segment DPL  0 THEN #GP(new code segment selector); FI;
GOTO INTERRUPT-FROM-VIRTUAL-8086-MODE;
(* PE=1, interrupt or trap gate, DPLCPL, VM=1 *)
IF VM=1 THEN #GP(new code segment selector); FI;
IF code segment is conforming OR code segment DPL = CPL
THEN
GOTO INTRA-PRIVILEGE-LEVEL-INTERRUPT;
ELSE
#GP(CodeSegmentSelector + EXT);
(* PE=1, interrupt or trap gate, nonconforming *)
(* code segment, DPL>CPL *)
FI;
Volume 4: Base IA-32 Instruction Reference