Specifications

C–10 SROM Initialization

Subject to Change – 17 January 1997

Icache Flush Code

C.9 Icache Flush Code

The following code is loaded into memory after the system ROM image. The code is

then executed to flush the SROM initialization code from the Icache. The SROM

initialization code is loaded into the Icache and maps to memory beginning at

address zero.

77FF0119 mt r31, flushIc

C0000001 br r0, +4

.long destination

6C008000 ldl_p r0, 0x0 (r0)

47FF041F bis r31, 31, 31

. (total of 44 bis instructions)

47FF041F bis r31, 31, 31

6BE00000 jmp r31, (r0)

In an attempt to transfer execution to the first page in memory, execution would

continue in the SROM initialization code at that address. Therefore, execution must

be transferred to some address that does not hit in the Icache where other code can

flush the Icache.

The NOPs following the Icache flush allow the instructions that were fetched before

the Icache was updated to be cleared from the pipeline. Execution will ultimately

continue at the address contained in r0. At this point r0 contains the starting address

where the system flash ROM image was loaded into memory.