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2-34 Computer Group Literature Center Web Site

Hawk PCI Host Bridge & Multi-Processor Interrupt Controller

The Hawk’s PCI arbiter has various programming options. It supports 3

different priority schemes: fixed, round robin and mixed mode. It also

allows various levels of reprioritization programming options within fixed

and mixed modes. Parking can be programmed to any of the requestors, the

last requestor or none. A special bit is added to hold grant asserted for an

agent that initiates a lock cycle. Once a lock cycle is detected, the grant is

held asserted until the PCI LOCK_ pin is released. This feature works only

when the “POL” bit is enabled.

The priority scheme can be programmed by writing the “PRI” field in the

PCI Arbiter control register. The default setting for priority scheme is fixed

mode. The Fixed mode holds each requestor at a fixed level in its

hierarchy. The levels of priority for each requestor is programmable by

writing the “HEIR” field in the PCI Arbiter control register. Table 2-

describes all available settings for the “HEIR” field in fixed mode.

Table 2-10. Fixed Mode Priority Level Setting

HEIR

Setting

Priority Levels

Highest Lowest

000

PARB6 PARB5 PARB4 PARB3 PARB2 PARB1 PARB0 HAWK

001

HAWK PARB6 PARB5 PARB4 PARB3 PARB2 PARB1 PARB0

010

PARB0 HAWK PARB6 PARB5 PARB4 PARB3 PARB2 PARB1

011

PARB1 PARB0 HAWK PARB6 PARB5 PARB4 PARB3 PARB2

100

PARB2 PARB1 PARB0 HAWK PARB6 PARB5 PARB4 PARB3

101

PARB3 PARB2 PARB1 PARB0 HAWK PARB6 PARB5 PARB4

110

PARB4 PARB3 PARB2 PARB1 PARB0 HAWK PARB6 PARB5

111

PARB5 PARB4 PARB3 PARB2 PARB1 PARB0 HAWK PARB6

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Motorola MVME2400 Series Manuale di Servizio Pagina 92