Get_PM_Int_Type

include vmm.inc

mov     eax, Interrupt    ; number of interrupt to check
VMMCall Get_PM_Int_Type

mov     [Type], edx       ; 0 if trap gate, else interrupt gate
 

Determines whether a protected-mode interrupt vector is an interrupt gate or trap-gate type interrupt. Uses EDX, Flags.

• Returns zero in the EDX register if the interrupt corresponds to a trap gate, a nonzero value if the it corresponds to an interrupt gate.

Interrupt

Number of the interrupt to check.

An interrupt that passes through an interrupt gate automatically clears the interrupt flag bit to disable interrupts. Interrupts that pass through a trap gate do not modify the interrupt bit. All protected-mode interrupts default to the trap-gate type, but virtual devices such as the virtual PIC device, may change some trap gates to interrupt gates so that hardware interrupts disable interrupts. The virtual PIC device leaves software interrupts, such as Interrupt 21h, unchanged. This avoids an unnecessary ring transition by eliminating the need for the software interrupt handlers to execute an sti instruction.

See Also

Get_PM_Int_Vector, Set_PM_Int_Type