E.2.3 Primary And Secondary Hash Address Registers (Hash1 And Hash2) - Motorola MPC8240 User Manual

Implementation-Specific Registers from 603e
E.2.3 Primary and Secondary Hash Address Registers
(HASH1 and HASH2)
The HASH1 and HASH2 registers contain the physical addresses of the primary and
secondary PTEGs for the access that caused the TLB miss exception. For convenience, the
603e automatically constructs the full physical address by routing bits 0–6 of SDR1 into
HASH1 and HASH2 and clearing the lower 6 bits. These registers are read-only and are
constructed from the contents of the DMISS or IMISS register (the register choice is
determined by which miss was last acknowledged). The format for the HASH1 and HASH2
registers is shown in Figure E-24.
HTABORG[0–6]
0 6 7
Table E-17 describes the bit settings of the HASH1 and HASH2 registers.
Bits
0–6 HTABORG[0–6]
7–25 Hashed page address
26–31 —
E.2.4 Required Physical Address Register (RPA)
The RPA register is shown in Figure E-25. During a page table search operation, the
software must load the RPA with the second word of the correct PTE. When the tlbld or
tlbli instruction is executed, the contents of the RPA register and the DMISS or IMISS
register are merged and loaded into the selected TLB entry. The referenced (R) bit is
ignored when the write occurs (no location exists in the TLB entry for this bit). The RPA
register can be read and written by software.
0
Figure E-25. Required Physical Address Register (RPA)
E-22
Hashed Page Address
Figure E-24. HASH1 and HASH2 Registers
Table E-17. HASH1 and HASH2 Bit Settings
Name
Copy of the upper 7 bits of the HTABORG field from SDR1
Address bits 7–25 of the PTEG to be searched
Reserved
RPN
MPC8240 Integrated Processor User's Manual
25 26
Description
0 0 0 R C
19 20 22 23 24 25
0 0 0 0 0 0
31
Reserved
WIMG 0 PP
28 29 30 31