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88 SPARC JPS1 Implementation Supplement: Fujitsu SPARC64 V • Release 1.0, 1 July 2002
F.3.3 TSB Organization
IMPL. DEP. #227
:
The maximum number of entries in a TSB is implementation
dependent in JPS1. See impl. dep. #228 for the limitation of
TSB_size
in TSB
registers.
SPARC64 V supports a maximum of 16 million lines in the common TSB and a
maximum 32 million lines in the split TSB. The maximum number
N
in
FIGURE
F-4 of
Commonality
is
16 million (16 * 2
20
).
F.4.2 TSB Pointer Formation
IMPL. DEP. #228
:
Whether
TSB_Hash
is supplied from a TSB Extension Register or
from a context-ID register is implementation dependent in JPS1. Only for cases of
direct hash with context-ID can the width of the
TSB_size
field be wider than 3
bits.
On SPARC64 V,
TSB_Hash
is supplied from a context-ID register. The width of
the
TSB_size
field is 4 bits.
IMPL. DEP. #229
:
Whether the implementation generates the TSB Base address by
exclusive-ORing the TSB Base Register and a TSB Extension Register or by taking the
TSB_Base
field directly from the TSB Extension Register is implementation
dependent in JPS1. This implementation dependency is only to maintain
compatibility with the TLB miss handling software of UltraSPARC I/II.
On SPARC64 V, when
ASI_MCNTL.JPS1_TSBP
= 1, the TSB Base address is
generated by taking
TSB_Base
field directly from the TSB Extension Register.
TSB Pointer Formation
On SPARC64 V, the number N in the following equations ranges from 0 to 15; N is
defined to be the
TSB_Size
field of the TSB Base or TSB Extension Register.
SPARC64 V supports the TSB Base from TSB Extension Registers as follows when
ASI_MCNTL.JPS1_TSBP
=1.
For a shared TSB (TSB Register split field = 0):
8K_POINTER = TSB_Extension[63:13+N] (VA[21+N:13] ⊕ TSB_Hash)
0000
64K_POINTER = TSB_Extension[63:13+N]
(VA[24+N:16] ⊕ TSB_Hash)
0000
For a split TSB (TSB Register split field = 1):