Compaq EV68A specifications Instruction Virtual Address Format Register Ivaform

Ibox IPRs

5.2.8 Instruction Virtual Address Format Register — IVA_FORM

The instruction virtual address format register (IVA_FORM) is a read-only register. It contains the virtual PTE address derived from the faulting virtual address stored in the EXC_ADDR register, and from the virtual page table base, VA_48 and VA_FORM_32 bits, stored in the I_CTL register.

Figure 5–13shows IVA_FORM when I_CTL(VA_48) equals 0 and

I_CTL(VA_FORM_32) equals 0.

Figure 5–13 Instruction Virtual Address Format Register (VA_48 = 0, VA_FORM_32 = 0)

63 33 32 3 2 0

VPTB[63:33]

VA[42:13] LK99-0019A

Figure 5–14shows IVA_FORM when I_CTL(VA_48) equals 1 and

I_CTL(VA_FORM_32) equals 0.

Figure 5–14 Instruction Virtual Address Format Register (VA_48 = 1, VA_FORM_32 = 0)

63 43 42 38 37 3 2 0

VPTB[63:43]

SEXT(VA[47])

VA[47:13] LK99-0020A

Figure 5–15shows IVA_FORM when I_CTL(VA_48) equals 0 and

I_CTL(VA_FORM_32) equals 1.

Figure 5–15 Instruction Virtual Address Format Register (VA_48 = 0, VA_FORM_32 = 1)

63 30 29 22 21 3 2 0

VPTB[63:30]

VA[31:13] LK99-0021A

5.2.9 Interrupt Enable and Current Processor Mode Register – IER_CM

The interrupt enable and current processor mode register (IER_CM) contains the inter- rupt enable and current processor mode bit fields. These bit fields can be written either individually or together with a single HW_MTPR instruction. When bits [7:2] of the IPR index field of a HW_MTPR instruction contain the value 0000102, this register is selected. Bits [1:0] of the IPR index indicate which bit fields are to be written: bit[1] corresponds to the IER field and bit[0] corresponds to the processor mode field. A HW_MFPR instruction to this register returns the values in both fields. Figure 5–16shows the interrupt enable and current processor mode register.

21264/EV68A Hardware Reference Manual Internal Processor Registers 5–9