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7-2 Vol. 3
TASK MANAGEMENT
7.1.2 Task State
The following items define the state of the currently executing task:
• The task’s current execution space, defined by the segment selectors in the
segment registers (CS, DS, SS, ES, FS, and GS).
• The state of the general-purpose registers.
• The state of the EFLAGS register.
• The state of the EIP register.
• The state of control register CR3.
• The state of the task register.
• The state of the LDTR register.
• The I/O map base address and I/O map (contained in the TSS).
• Stack pointers to the privilege 0, 1, and 2 stacks (contained in the TSS).
• Link to previously executed task (contained in the TSS).
Prior to dispatching a task, all of these items are contained in the task’s TSS, except
the state of the task register. Also, the complete contents of the LDTR register are not
contained in the TSS, only the segment selector for the LDT.
Figure 7-1. Structure of a Task
Code
Segment
Stack
Segment
(Current Priv.
Data
Segment
Stack Seg.
Priv. Level 0
Stack Seg.
Priv. Level 1
Stack
Segment
(Priv. Level 2)
Task-State
Segment
(TSS)
Task Register
CR3
Level)