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3-24 Software Environment and Extensions

AMD-K5 Processor Technical Reference Manual 18524C/0—Nov1996

3.1.5 Protected Virtual Interrupt (PVI) Extensions

The Protected Virtual Interrupts (PVI) bit in CR4 enables sup-

port for interrupt virtualization in Protected mode. In this vir-

tualization, the processor maintains program-specific VIF and

VIP flags in a manner similar to those in Virtual-8086 Mode

Extensions (VME). When a program is executed at CPL = 3, it

can set and clear its copy of the VIF flag without causing gen-

eral-protection exceptions.

The only differences between the VME and PVI extensions are

that, in PVI, selective INTn interception using the Interrupt

Redirection Bitmap in the TSS does not apply, and only the STI

and CLI instructions are affected by the extension.

Table 3-5A through Table 3-5E and Table 3-6 show, among

other things, the behavior of hardware and software inter-

rupts, and instructions that affect interrupts, in Protected

mode with the PVI extensions enabled.

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