In the 80386 microprocessor and later, virtual 8086 mode (also called virtual real mode, V86-mode, or VM86) allows the execution of real mode applications that are incapable of running directly in protected mode while the processor is running a protected mode operating system.

The processor leaves V86 mode as the result of an exception or interrupt that vectors via a trap or interrupt gate to a privilege-level zero procedure. The exception or interrupt handler returns to the 8086 code by executing an IRET .

2023年11月10日 · 进入保护模式后，可以利iret 设置eflags寄存器中VM位 从而进入V86 mode。 返回保护模式是用sysenter指令返回。 4、使用iret指令前要将eglags中的IOPL设置为3，这样执行iret、sysenter指令不会报错；1、V86 mode是运行在CPL 3特权下的，操作代码是16位；5、寻方式为 段：偏移，1M范围内；3、需先初始化 GDT、IDT；2、分页机制有保护标志；_v86模式代码.

2016年11月8日 · 虚拟8086模式是保护模式下的一种工作方式，也称为V8086模式，或者简称为V86模式。 在 虚拟8086模式下，处理器类似于8086。 寻址的地址空间是1M字节；段寄存器的内容作为段 值解释；20位存储单元地址由段值乘以16加偏移构成。 在V86模式下，代码段总是可写的， 这与实模式相同，同理，数据段也是可执行的，只不过可能会发生异常。 所以，在虚 拟8086模式下，可以运行DOS及以其为平台的软件。 但V86模式毕竟是虚拟8086的一种方 式，所以不 …

Chapter 15 Virtual 8086 Mode. The 80386 supports execution of one or more 8086, 8088, 80186, or 80188 programs in an 80386 protected-mode environment. An 8086 program runs in this environment as part of a V86 (virtual 8086) task. V86 tasks take advantage of the hardware support of multitasking offered by the protected mode.

Virtual 8086 mode is a sub-mode of Protected mode. In short, Virtual 8086 mode is whereby the CPU (in protected mode) is running a "Emulated" 16bit Real Mode machine. The CPU is executing in virtual 86 mode when the VM bit (bit 17) is set in the EFLAGS register. If you want to enter virtual 86 mode you must set this bit to 1.

Virtual 8086 mode (also called V86 mode) is a dynamic mode in the sense that the processor can switch repeatedly and rapidly between V86 mode and protected mode. The CPU enters V86 mode from protected mode to execute an 8086 program, then leaves V86 mode and enters protected mode to continue executing a native 80386 program.

The processor enters V86 mode to execute the 8086 program and returns to protected mode to execute the monitor or other 80386 tasks. To run successfully in V86 mode, an existing 8086 program needs the following:

v86模式是386及以上处理器所独有的运行模式,它全兼容实模式下所有处理方式,并运用分页机构进行内存管理。 分页机构的处理单位是固定大小为4KB的页面,它把32位的线性地址分成三部分,即两个指向页表的10位变址和一个12位的页面偏移值(线性地址的格式见下面左 ...

In the 80386 microprocessor and later, virtual 8086 mode (also called virtual real mode, V86-mode, or VM86) allows the execution of real mode applications that are incapable of running directly in protected mode while the processor is running a protected mode operating system.