SH7708 Datasheet, PDF (70/625 Pages) Renesas Technology Corp – SuperH™ RISC engine

Address Space Identifier (ASID): When multiple processes run in parallel sharing the same
virtual address space and the processes have unique address translation tables, the virtual space can
be multiplexed. The ASID is 8 bits in length and is held in PTEH within the MMU indicating the
current process. With ASID, the TLB need not be purged when the process is switched.
When multiple processes run in parallel using the virtual address space exclusively, the physical
address corresponding to a given virtual address is specified uniquely. For this kind of single virtual
memory, the ASID becomes a key to protect memory (see section 3.4.2).
3.1.4 Register Configuration
A register that has an undefined initial value must be initialized by the software. Table 3.1 shows
the configuration of the MMU control registers.
Table 3.1 Register Configuration
Name
Abbreviatio R / Size
n
W
Page table entry register
high
PTEH
R/W Longword
Page table entry register low PTEL
R/W Longword
Translation table base
TTB
register
R/W Longword
TLB exception address
TEA
register
R/W Longword
MMU control register
MMUCR
R/W Longword
Notes: 1. Initialized by a power-on reset or manual reset.
2. SV bit: undefined
Other bits: 0
Initial
Value*¹
Undefined
Undefined
Undefined
Undefined
*²
Address
H'FFFFFFF0
H'FFFFFFF4
H'FFFFFFF8
H'FFFFFFFC
H'FFFFFFE0
56