User's Manual

7-12 Vol. 3
TASK MANAGEMENT
to be handled by handler tasks. When an interrupt or exception vector points to
a task gate, the processor switches to the specified task.
Figure 7-7 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.
7.3 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.
Figure 7-7. Task Gates Referencing the Same Task
LDT
Task Gate
TSSGDT
TSS Descriptor
IDT
Task Gate
Task Gate