UM0434 datasheet(200/390 Pages) STMICROELECTRONICS

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UM0434

Memory management unit

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the search occurs if a TLB invalidate or replacement removes the entry between the time

the exception is recognized and when the tlbsx is executed.

The supervisor instructions tlbre, tlbwe, tlbsx, tlbivax, and tlbsync are fully described in

the

EREF.

●

TLB Read Entry (tlbre)—Causes contents of the TLB entry specified by

MAS0[TLBSEL,ESEL]) to be placed into MAS1–MAS3.

Table 156 describes how MAS

fields are updated.

●

TLB Write Entry (tlbwe)—Causes the contents of certain fields within the MAS1,

MAS2, and MAS3 to be written into the TLB entry specified by MAS0[TLBSEL,ESEL].

Table 156 describes how MAS fields are updated.

●

TLB Search Indexed (tlbsx)—Updates the MAS registers conditionally based on

success or failure of a TLB lookup. The lookup is controlled by an effective address

provided by rB as specified in the instruction encoding, and by MAS6[SAS,SPID]. The

values placed into MAS0–MAS3 differ depending on the success of the search.

Table 156 describes how MAS fields are updated.

●

TLB Invalidate (tlbivax)—Invalidates TLB entries that correspond to the virtual address

calculated by this instruction. The address is detailed in

Table 153. No other

information except for that shown in

Table 153 is used for the invalidation (AS and TID

values are ignored).

Additional information about the targeted TLB entries is encoded in two of the lower bits

of the effective address calculated by the tlbivax.

EA[0–19] are used to perform the tlbivax invalidation of TLB1.

●

TLB Synchronize (tlbsync)—Treated as a privileged no-op by the e200z3.

7.5

TLB operations

This section describes how the software (with some hardware assistance) maintains TLB1.

Table 153.

tlbivax EA bit definitions

Bits

Field

0–19

EA[0–19]

20–27 Reserved(1)

These bits should be zero for future compatibility. They are ignored.

TLBSEL (1 = TLB1). Should be set, for future compatibility and to ensure that TLB1 is

targeted by the invalidate.

INV_ALL. If set, indicates that the invalidate operation needs to completely invalidate all

TLB1 entries that are not marked as invalidation protected (IPROT = 1)

30–31 Reserved 1

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