GT-64260A Design Guide
Doc. No. MV-S300165-00, Rev. A
CONFIDENTIAL
Copyright © 2002 Marvell
Page 28
Document Classification: Proprietary Information
May 21, 2002, Preliminary
Figure 7: Two CPUs Connected Through an External Arbiter
Notes
•
When using the IBM PPC750CX/e and some of the 750FX versions (see
) with multiple masters on the data bus an external 60x bus must be used. For
more information, see the GT-64260A Restrictions and Errata document.
•
For multiple CPU timing requirements, see Section
14.4.2 "Timing Simulation" on page 95
3.7.2 Symmetric Multiple Processing Systems Requirements
Symmetric Multiple Processing (SMP) systems provide increased computational power in an industry-accepted
manner that can be supported by numerous operating systems as well as middleware, such as database systems.
Boot Sequence
After reset pins de-assertion, each CPU begins executing a location in ROM. This is the start of the system firm-
ware execution that eventually provides the interfaces to the operating system.
One of the first things that firmware does is establish one of the processors as the master. The master is a single
processor that continues with the rest of the booting process. All of the other processors are placed in a stopped
state. A processor in this stopped state does nothing that affects the state of the system and will remain in this
state until accessed by an external event, such as an Inter-Processor Interrupts (IPIs).
The GT-64260A achieves the same goal by masking the BR1* pin from the internal arbiter. This causes the arbiter
to think that only CPU0 needs the bus and it does not grant the bus to CPU1. To enable CPU1 arbitration, set the
CPU Master Control register’s
MaskBR1
bit [9], at offset: 0x160 to ‘0’.
60x Arbiter
CPU1
CPU0
GT_BR* GT_BG* GT_DBG*
DBG*
BG*
BR*
DBG0*
DBG1*
BG0*
BG1*
BR0*
BR1*
DBG*
BG*
BR*
GT-64260A
GT_DBG*
GT_BG*
GT_BR*