Opcodes Reserved for PALcode

Figure 6–1 HW_LD Instruction Format

31

26 25

21 20

16 15

13 12 11

0

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

OPCODE

 

 

 

RA

 

RB

 

 

 

 

 

 

 

 

 

 

DISP

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

TYPE

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

LEN

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

FM-05654.AI4

Table 6–3describes the HW_LD instruction fields.

Table 6–3 HW_LD Instruction Fields Descriptions

Extent

Mnemonic

Value

Description

 

 

 

 

[31:26]

OPCODE

1B16

The opcode value.

[25:21]

RA

Destination register number.

[20:16]

RB

Base register for memory address.

[15:13]

TYPE

0002

Physical — The effective address for the HW_LD instruction is physical.

 

 

0012

Physical/Lock — The effective address for the HW_LD instruction is

 

 

 

physical. It is the load lock version of the HW_LD instruction.

 

 

0102

Virtual/VPTE — Flags a virtual PTE fetch (LD_VPTE). Used by trap logic

 

 

 

to distinguish a single TB miss from a double TB miss. Kernel mode access

 

 

 

checks are performed.

 

 

1002

Virtual — The effective address for the HW_LD instruction is virtual.

 

 

1012

Virtual/WrChk — The effective address for the HW_LD instruction is

 

 

 

virtual. Access checks for fault-on-read (FOR), fault-on-write (FOW), read

 

 

 

and write protection.

 

 

1102

Virtual/Alt — The effective address for the HW_LD instruction is virtual.

 

 

 

Access checks use DTB_ALT_MODE IPR.

 

 

1112

Virtual/WrChk/Alt — The effective address for the HW_LD instruction is

 

 

 

virtual. Access checks for FOR, FOW, read and write protection. Access

 

 

 

checks use DTB_ ALT_MODE IPR.

[12]

LEN

0

Access length is longword.

 

 

1

Access length is quadword.

[11:0]

DISP

Holds a 12-bit signed byte displacement.

 

 

 

 

6.4.2 HW_ST Instruction

PALcode uses the HW_ST instruction to access memory outside the realm of normal Alpha memory management and to do special forms of Dstream store instructions. Data alignment traps are inhibited for HW_ST instructions. Figure 6–2shows the HW_ST instruction format.

Figure 6–2 HW_ST Instruction Format

31

26 25

21 20

16 15

13 12 11

0

OPCODE

TYPE

RA

RB

DISP

LEN

FM-05654.AI4

 

6–4

Privileged Architecture Library Code

Alpha 21264/EV67 Hardware Reference Manual

Page 188
Image 188
Compaq EV67, 21264 specifications Opcodes Reserved for PALcode, Hwst Instruction, 3describes the Hwld instruction fields