Compaq 21264 - Manual (Page 198)

6–14 Privileged Architecture Library Code Alpha 21264/EV67 Hardware Reference Manual
Translation Buffer (TB) Fill Flows
6.9 Translation Buffer (TB) Fill Flows
This section shows the expected PALcode flows for DTB miss and ITB miss. Familiar-
ity with 21264/EV67 IPRs is assumed.
6.9.1 DTB Fill
Figure 6–5 shows single-miss DTB instructions flow.
Figure 6–5 Single-Miss DTB Instructions Flow Example
Figure 6–5 shows single-miss DTB instructions flow.
hw_mfprp23, EV6__EXC_ADDR ; (0L) get exception address
hw_mfprp4, EV6__VA_FORM ; (4-7,1L) get vpte address
hw_mfprp5, EV6__MM_STAT ; (0L) get miss info
hw_mfpr p7, EV6__EXC_SUM ; (0L) get exc_sum for ra
hw_mfpr p6, EV6__VA ; (4-7,1L) get original va
bic p7, #1, p7 ; clear double miss flag
xor p4, p6, p4 ; interlock p4 and p6
xor p4, p6, p4 ; restore p4
trap__dtbm_single_vpte:
hw_ldq/v p4, (p4) ; (1L) get vpte
blt p_misc, trap__d1to1 ; (xU) <63>=1 => 1-to-1
blbcp4, trap__invalid_dpte ; (xU) invalid => branch
and p4, #^x80, p7 ; isolate mb bit
xor p7, #^x80, p7 ; flip mb bit
ALIGN_FETCH_BLOCK <^x47FF041F>
PVC_VIOLATE <2> ; ignore scoreboard violation
hw_mtprp6, EV6__DTB_TAG0 ; (2&6,0L) write tag0
hw_mtpr p6, EV6__DTB_TAG1 ; (1&5,1L) write tag1
MCHK Interrupt 500 Machine check.
ITB_MISS Fault 580 Istream TB miss.
ARITH Synch. Trap 600 Arithmetic exception or update to FPCR.
INTERRUPT Interrupt 680 Interrupts: hardware, software, and AST.
MT_FPCR Synch. Trap 700 Invoked when a MT_FPCR instruction is issued.
RESET/WAKEUP Interrupt 780 Chip reset or wake-up from sleep mode.
Table 6–8 PALcode Exception Entry Locations (Continued)
Entry Name Type Offset
16
Description