Compaq 21264 - Manual (Page 169)

Alpha 21264/EV67 Hardware Reference Manual Internal Processor Registers 5–27
Mbox IPRs
Table 5–17 describes the DTB_ALTMODE register fields.
5.3.4 Dstream TB Invalidate All Process (ASM=0) Register – DTB_IAP
The Dstream translation buffer invalidate all process (ASM=0) register (DTB_IAP) is a
write-only pseudo register. Write transactions to this register invalidate all DTB entries
in which the address space match (ASM) bit is clear.
5.3.5 Dstream TB Invalidate All Register – DTB_IA
The Dstream translation buffer invalidate all register (DTB_IA) is a write-only pseudo
register. Write transactions to this register invalidate all DTB entries and reset the DTB
not-last-used pointer to its initial state.
5.3.6 Dstream TB Invalidate Single Registers 0 and 1 – DTB_IS0,1
The Dstream translation buffer invalidate single registers (DTB_IS0 and DTB_IS1) are
write-only pseudo registers through which software may invalidate a single entry in the
DTB arrays. Writing a virtual page number to one of these registers invalidates any
DTB entry in the corresponding memory pipeline which meets one of the following cri-
teria:
• The DTB entry’s virtual page number matches DTB_IS[47:13] and its ASN field
matches DTB_ASN[63:56].
• The DTB entry’s virtual page number matches DTB_IS[47:13] and its ASM bit is
set.
Figure 5–29 shows the Dstream translation buffer invalidate single registers.
Figure 5–29 Dstream Translation Buffer Invalidate Single Registers
Table 5–17 DTB Alternate Processor Mode Register Fields Description
Name Extent Type Description
Reserved [63:2] — —
ALT_MODE[1:0] [1:0] WO Alt_Mode:
ALT_MODE[1:0] Mode
00 Kernel
01 Executive
10 Supervisor
11 User
63 48 47 13 12 0
VA[47:13] LK99-0015A