Intel ARCHITECTURE IA-32 User Manual Page 562

  • Download
  • Add to my manuals
  • Print
  • Page
    / 636
  • Table of contents
  • BOOKMARKS
  • Rated. / 5. Based on customer reviews
Page view 561
15-12 Vol. 3A
8086 EMULATION
Figure 15-3. Entering and Leaving Virtual-8086 Mode
Monitor
Virtual-8086
Real Mode
Code
Protected-
Mode Tasks
Virtual-8086
Mode Tasks
(8086
Programs)
Protected-
Mode Interrupt
and Exception
Handlers
Task Switch
1
VM = 1
Protected
Mode
Virtual-8086
Mode
Real-Address
Mode
RESET
PE=1
PE=0 or
RESET
#GP Exception
3
CALL
RET
Task Switch
VM=0
Redirect Interrupt to 8086 Program
Interrupt or Exception Handler
6
IRET
4
Interrupt or
Exception
2
VM = 0
NOTES:
- CALL or JMP where the VM flag in the EFLAGS image is 1.
- IRET where VM is 1 and NT is 1.
4. Normal return from protected-mode interrupt or exception handler.
3. General-protection exception caused by software interrupt (INT n), IRET,
POPF, PUSHF, IN, or OUT when IOPL is less than 3.
2. Hardware interrupt or exception; software interrupt (INT n) when IOPL is 3.
5. A return from the 8086 monitor to redirect an interrupt or exception back
to an interrupt or exception handler in the 8086 program running in virtual-
6. Internal redirection of a software interrupt (INT n) when VME is 1,
IOPL is <3, and the redirection bit is 1.
IRET
5
8086 mode.
1. Task switch carried out in either of two ways:
Page view 561
1 2 ... 557 558 559 560 561 562 563 564 565 566 567 ... 635 636

Comments to this Manuals

No comments