3.When the LBSY on the SB is changed, LBSY change information is broadcast to all CPUs in the SB. Each CPU receives the change information and updates its copy.

4.On a read from an application, the copy value of LBSY, which is designated by supervisor software, is returned.

High-Speed BST Write Mechanism

1.An application writes value, designated by supervisor software, to a BST.

2.The CPU sends BST write information to the system controller.

3.The system controller writes the BST.

A write to BST is faster than a noncacheable store.

L.4.2 ASI Registers

LBSY Control Register (ASI_C_LBSYR0, ASI_C_LBSYR1)

[1]Register Name: ASI_C_LBSYR0, ASI_C_LBSYR1

[2]

ASI:

6F16

[3]

VA:

0016 (ASI_C_LBSYR0), 0816 (ASI_C_LBSYR1).

[4]

RW

Supervisor read/write

The LBSY control register designates which bit in the copy of LBSY is read through ASI_LBSYRx.

Bit

Name

RW

Description

 

 

 

 

63

V

RW

Valid. When V = 0, BL_num and SB_BPU_num are ignored

 

 

 

and a read to ASI_LBSYRx always returns 0. On V = 1,

 

 

 

the copy value of LBSY selected by BL_num and

 

 

 

SB_BPU_num is read.

3

SB_BPU_num

RW

SB BPU relative number on the SB.

2:0

BL_num

RW

BL number in the selected SB BPU.

 

 

 

 

122 SPARC JPS1 Implementation Supplement: Fujitsu SPARC64 V • Release 1.0, 1 July 2002

Page 133
Image 133
Fujitsu Fujitsu SPARC64 V ASI Registers, High-Speed BST Write Mechanism, Lbsy Control Register ASICLBSYR0, ASICLBSYR1