Compaq 21264 - Manual (Page 222)

7–14 Initialization and Configuration Alpha 21264/EV67 Hardware Reference Manual
External Interface Initialization
SweepMemory: ;Write good parity/ecc to memory by
; writing a all memory locations. This is
;done by WH64 of memory addresses
turn_on_bcache: ;bc_enable_a 0
;bc_size_a Actual Bcache size
;zeroblk_enable_a 3
;set_dirty_enable_a 6
;init_mode_a 0
;enable_evict_a 0
;bc_wrt_sts_a 0
;bc_bank_enable_a 0
for 2 X bc_size ;This loop generates legal ECC data, and
{ WH64 address } ;invalidate tags which are written to the
;Bcache for all but the final 64KB of address.
for 2 X dcache size
{ ECB address } ;and cleans up the Dcache also.
(done)
In addition to initialization, the dynamic programming ability of the WRITE_MANY
chain provides the basic tools to build various other software flows such as dynamically
changing the Bcache enable/size parameters for performance testing.
7.7 External Interface Initialization
After reset, the system interface is in the default configuration dictated by the reset state
of the IPR bits that select the configuration options.
The response to system interface commands and internally generated memory accesses
is determined by this default configuration. System environments that are not compati-
ble with the default configuration must use the SROM Icache load feature to initially
load and execute a PALcode program to configure the external system interface unit
IPRs as needed.
7.8 Internal Processor Register Power-Up Reset State
Many IPR bits are not initialized by reset. They are located in error-reporting registers
and other IPR states. They must be initialized by initialization PALcode. Tables 7–5,
7–6, and 7–8, list the effects on IPRs by fault reset, transition through sleep mode, and
warm reset, respectively. Table 7–10 lists the state of all internal processor registers
(IPRs) immediately following power-up reset. The table also specifies which registers
need to be initialized by power-up PALcode.
Table 7–10 Internal Processor Registers at Power-Up Reset State
Mnemonic Register Name Reset State Comments
Ibox IPRs
ITB_TAG ITB tag array write X —
ITB_PTE ITB PTE array write X —