Motorola MVME2400 Series Wartungshandbuch PDF herunterladen (Seite 72)

2-14 Computer Group Literature Center Web Site

Hawk PCI Host Bridge & Multi-Processor Interrupt Controller

The PPC master incorporates an optional operating mode called Bus Hog.

When Bus Hog is enabled, the PPC master will continually request the

PPC bus for the entire duration of each PCI transfer. When Bus Hog is not

enabled, the PPC master will structure its bus request actions according to

the requirements of the FIFO. The Bug Hog mode was primarily designed

to assist with system level debugging and is not intended for normal modes

of operation. It is a brute force method of guaranteeing that all PCI to

PPC60x transactions will be performed without any intervention by host

CPU transactions. Caution should be exercised when using this mode since

the over-generosity of bus ownership to the PPC master can be detrimental

to the host CPU’s performance. The Bus Hog mode can be controlled by

the XMBH bit within the GCSR. The default state for XMBH is disabled.

PPC Arbiter

PHB has an internal PPC60x bus arbiter. The use of this arbiter is optional.

If the internal arbiter is disabled, then the PHB must be allowed to

participate in an externally implemented PPC60x arbitration mechanism.

Table 2-5. PPC Master Transfer Types

PCI Command Code INV PPC Transfer Type PPC Transfer Size TT0-TT4

Memory Read

Memory Read Multiple

Memory Read Line

0 Read Burst/Single Beat 01010

Memory Read

Memory Read Multiple

Memory Read Line

1 Read With Intent to

Modify

Burst/Single Beat 01110

Memory Write

Memory Write and

Invalidate

x Write with Kill Burst 00110

Memory Write

Memory Write and

Invalidate

x Write with Flush Single Beat 00010

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Motorola MVME2400 Series Wartungshandbuch Seite 72