Restriction 9 : PALmode Istream Address Ranges

Bad_interrupt_flow_entry:

ADDQ R31,R31,R0

STF Fa,(Rb) ; This STF might not undergo a dirty source register

;check and might give wrong results ADDQ R31,R31,R0

ADDQ R31,R31,R0

................................

Good_interrupt_flow_entry:

ADDQ R31,R31,R0; Enables FP dirty source register

;check for (PC[1:0] == 00)

ADDQ R31,R31,R0; Enables FP dirty source register ; check for (PC[1:0] == 01)

ADDQ R31,R31,R0; Enables FP dirty source register ; check for (PC[1:0] == 10)

ADDQ R31,R31,R0; Enables FP dirty source register

;check for (PC[1:0] == 11) ADDQ R31,R31,R0

STF Fa,(Rb); This STF will successfully undergo

;a dirty source register check

ADDQ R31,R31,R0

ADDQ R31,R31,R0

D.6 Restriction 9 : PALmode Istream Address Ranges

PALmode[physical] Istream addresses must ensure proper sign extension for the selected value of I_CTL[VA_48]. When I_CTL[VA_48] is clear, indicating 43-bit vir- tual address format, PALmode[physical] Istream addresses must sign-extend address bits above bit 42 although the physical address range is 44 bits. An illegal address can only be generated by a PALmode JSR-type instruction or a HW_RET instruction returning to a PALmode address.

D.7 Restriction 10: Duplicate IPR Mode Bits

The virtual address size is selectable by programming IPR bits I_CTL[VA_48] and VA_CTL[VA_48]. These bit values should usually be equal when operating in native (virtual) mode. The I_CTL[VA_48] bit determines the DTB double3/double4 PALcode entry, the JSR mispredict comparison width, the VPC address generation width, the Istream ACV limits, and the IVA_FORM format selection. The VA_CTL[VA_48] bit determines the VA_FORM format selection and the Dstream ACV limits. IPR mode bits I_CTL[VA_FORM_32] and VA_CTL[VA_FORM_32] should be consistent when executing in native mode.

D–10PALcode Restrictions and Guidelines

Alpha 21264/EV67 Hardware Reference Manual

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Compaq EV67, 21264 specifications Restriction 9 PALmode Istream Address Ranges, Restriction 10 Duplicate IPR Mode Bits