Memory Management Unit
MPC885 PowerQUICC Family Reference Manual, Rev. 2
8-32
Freescale Semiconductor
8.10.1.1
Translation Reload Examples
The following examples reload a TLB entry using a two-level tree page table structure. In both examples,
M_TWB holds the base pointer to the first-level table and data and instruction address translation are
turned off.
Figure 8-23
performs a DTLB reload.
Figure 8-24
performs an ITLB reload.
dtlb_swtw
mtspr
M_TW, R1
# Save R1
mfspr
R1, M_TWB
# Load R1 with level-1 pointer
lwz
R1, (R1)
# Load level-1 page entry
mtspr
MD_TWC,R1
# Save level-2 base pointer and level-1 attributes
mfspr
R1, MD_TWC
# Load R1 with level-2 pointer while taking page
# size into account
lwz
R1, (R1)
# Load level-2 page entry
mtspr
MD_RPN, R1
# Write TLB entry
mfspr
R1, M_TW
# Restore R1
rfi
Figure 8-23. DTLB Reload Code Example
itlb_swtw
mtspr
M_TW, R1
# Save R1
mfspr
R1, SRR0
# Load R1 with instruction miss EA (the same data
# may be taken from MI_EPN)
mtspr
MD_EPN, R1
# Save instruction miss EA in MD_EPN
mfspr
R1, M_TWB
# Load R1 with level-1 pointer
lwz
R1, (R1)
# Load level-1 page entry
mtspr
MI_TWC,R1
# Save level-1 attributes
mtspr
MD_TWC,R1
# Save level-2 base pointer
mfspr
R1, MD_TWC
# Load R1 with level-2 pointer while taking page
# size into account
lwz
R1, (R1)
# Load level-2 page entry
mtspr
MI_RPN, R1
# Write TLB entry
mfspr
R1, M_TW
# Restore R1
rfi
Figure 8-24. ITLB Reload Code Example
Summary of Contents for PowerQUICC MPC870
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