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Alpha 21264/EV67 Hardware Reference Manual
Internal Processor Registers 5–21
Ibox IPRs
5.2.17 Icache Flush Register – IC_FLUSH
The Icache flush register (IC_FLUSH) is a pseudo register. Writing to this register
invalidates all Icache blocks. The cache is flushed when the next HW_RET/STALL
instruction is retired. See Section D.20 for more information.
5.2.18 Icache Flush ASM Register – IC_FLUSH_ASM
The Icache flush ASM register (IC_FLUSH_ASM) is a pseudo register. Writing to this
register invalidates all Icache blocks with their ASM bit clear.
5.2.19 Clear Virtual-to-Physical Map Register – CLR_MAP
The clear virtual-to-physical map register (CLR_MAP) is a pseudo register that, when
written, results in the clearing of the current map of virtual to physical registers. This
register must only be written after there are no register-borne dependencies present and
there are no unretired instructions. See an example in the PALcode restrictions.
5.2.20 Sleep Mode Register – SLEEP
The sleep mode register (SLEEP) is a pseudo register that, when written, results in the
PLL speed being reduced and the chip entering a low-power mode. This register must
only be written after a sequence of code has been run which saves all necessary state to
DRAM, flushes the caches, and unmasks certain interrupts so the chip can be woken up.
See Section 7.3 for details.
5.2.21 Process Context Register – PCTX
The process context register (PCTX) contains information associated with the context
of a process. Any combination of the bit fields within this register may be written with
a single HW_MTPR instruction. When bits [7:6] of the IPR index field of a
HW_MTPR instruction contain the value 01
2
, this register is selected. Bits [4:0] of the
IPR index indicate which bit fields are to be written. Usage of PCTX in performance
monitoring is described in Section 6.10.
Table 5–13 lists the correspondence between IPR index bits and register fields.
A HW_MFPR from this register returns the values in all of its component bit fields.
Figure 5–24 shows the process context register.
Table 5–13 IPR Index Bits and Register Fields
IPR Index Bit Register Field
0ASN
1 ASTER
2ASTRR
3 PPCE
4 FPE