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[原创]VT真的是至高点吗？非也！
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发表于: 2010-5-7 21:28
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我们知道操作系统及驱动程序工作在Ring 0，而VT工作在Ring -1 (hypervisor mode)。
然而，自Intel 80386 SL开始，Intel CPU一直就支持System management mode (SMM)。SMM下有独立的地址空间，而且该地址空间对于VT或者保护模式均不可见，不管操作系统还是hypervisor都无法感知其存在，SMM下的程序作为“上帝”在而超越任何模式。
以下摘录自Intel官方文档：
System management mode (SMM) — SMM is a standard architectural feature in all IA-32 processors, beginning with the Intel386 SL processor. This mode provides an operating system or executive with a transparent mechanism for implementing power management and OEM differentiation features. SMM is entered through activation of an external system interrupt pin (SMI#), which generates a system management interrupt (SMI). In SMM, the processor switches to a separate address space while saving the context of the currently running program or task. SMM-specific code may then be executed transparently. Upon returning from SMM, the processor is placed back into its state prior to the SMI.
然而，自Intel 80386 SL开始，Intel CPU一直就支持System management mode (SMM)。SMM下有独立的地址空间，而且该地址空间对于VT或者保护模式均不可见，不管操作系统还是hypervisor都无法感知其存在，SMM下的程序作为“上帝”在而超越任何模式。
以下摘录自Intel官方文档：
System management mode (SMM) — SMM is a standard architectural feature in all IA-32 processors, beginning with the Intel386 SL processor. This mode provides an operating system or executive with a transparent mechanism for implementing power management and OEM differentiation features. SMM is entered through activation of an external system interrupt pin (SMI#), which generates a system management interrupt (SMI). In SMM, the processor switches to a separate address space while saving the context of the currently running program or task. SMM-specific code may then be executed transparently. Upon returning from SMM, the processor is placed back into its state prior to the SMI.
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apic,smm
chips都干啥的，同2楼 
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本人菜鸟。哈哈。。。。
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