Compaq EV67 User Manual
6–4
Privileged Architecture Library Code
Alpha 21264/EV67 Hardware Reference Manual
Opcodes Reserved for PALcode
Figure 6–1 HW_LD Instruction Format
Table 6–3 describes the HW_LD instruction fields.
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 6–2 shows the HW_ST
instruction format.
Alpha memory management and to do special forms of Dstream store instructions. Data
alignment traps are inhibited for HW_ST instructions. Figure 6–2 shows the HW_ST
instruction format.
Figure 6–2 HW_ST Instruction Format
Table 6–3 HW_LD Instruction Fields Descriptions
Extent
Mnemonic Value Description
[31:26]
OPCODE
1B
16
The opcode value.
[25:21]
RA
—
Destination register number.
[20:16]
RB
—
Base register for memory address.
[15:13]
TYPE
000
2
Physical — The effective address for the HW_LD instruction is physical.
001
2
Physical/Lock — The effective address for the HW_LD instruction is
physical. It is the load lock version of the HW_LD instruction.
physical. It is the load lock version of the HW_LD instruction.
010
2
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.
to distinguish a single TB miss from a double TB miss. Kernel mode access
checks are performed.
100
2
Virtual — The effective address for the HW_LD instruction is virtual.
101
2
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.
virtual. Access checks for fault-on-read (FOR), fault-on-write (FOW), read
and write protection.
110
2
Virtual/Alt — The effective address for the HW_LD instruction is virtual.
Access checks use DTB_ALT_MODE IPR.
Access checks use DTB_ALT_MODE IPR.
111
2
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.
virtual. Access checks for FOR, FOW, read and write protection. Access
checks use DTB_ ALT_MODE IPR.
[12]
LEN
0
1
Access length is longword.
Access length is quadword.
[11:0]
DISP
—
Holds a 12-bit signed byte displacement.
31
26 25
21 20
16 15
13
11
12
0
FM-05654.AI4
TYPE
LEN
DISP
RB
RA
OPCODE
31
26 25
21 20
16 15
13
11
12
0
FM-05654.AI4
TYPE
LEN
DISP
RB
RA
OPCODE