Intel IA-32 - Manual (Page 254)

6-12 Vol. 3A
TASK MANAGEMENT
Figure 6-7 illustrates how a task gate in an LDT, a task gate in the GDT, and a task gate in the
IDT can all point to the same task.
6.3 TASK SWITCHING
The processor transfers execution to another task in one of four cases:
•
The current program, task, or procedure executes a JMP or CALL instruction to a TSS
descriptor in the GDT.
•
The current program, task, or procedure executes a JMP or CALL instruction to a task-gate
descriptor in the GDT or the current LDT.
•
An interrupt or exception vector points to a task-gate descriptor in the IDT.
•
The current task executes an IRET when the NT flag in the EFLAGS register is set.
Figure 6-7. Task Gates Referencing the Same Task
LDT
Task Gate
TSS GDT
TSS Descriptor
IDT
Task Gate
Task Gate