Motorola MVME2400 Series Wartungshandbuch Seite 71

  • Herunterladen
  • Zu meinen Handbüchern hinzufügen
  • Drucken
  • Seite
    / 354
  • Inhaltsverzeichnis
  • LESEZEICHEN
  • Bewertet. / 5. Basierend auf Kundenbewertungen
Seitenansicht 70
Functional Description
http://www.mcg.mot.com/literature 2-13
2
Upon completion of a prefetched read transaction, any residual read data
left within the PCI FIFO will be invalidated (discarded). The PHB does not
have a mechanism for snooping the PPC60x bus for transactions
associated with the prefetched read data within the PCI FIFO, therefore
caution should be exercised when using the prefetch option within
coherent memory space.
The PPC Master will never perform prefetch reads beyond the address
range mapped within the PCI Slave map decoders. As an example, assume
PHB has been programmed to respond to PCI address range $10000000
through $1001FFFF with an offset of $2000. The PPC Master will perform
its last read on the PPC60x bus at cache line address $3001FFFC or word
address $3001FFF8.
The PPC60x bus transfer types generated by the PPC Master depend on the
PCI command code and the INV/GBL bits in the PSATTx registers. The
GBL bit determines whether or not the GBL_ signal is asserted for all
portions of a transaction and is fully independent of the PCI command
code and INV bit. A following table shows the relationship between the
PCI command codes and the INV bit.
00 xx 1 Read 4 cache lines FIFO <= 0
cache lines
FIFO >= 4
cache lines
Read Line
xx 00
x Read Multiple
01 xx 1 Read 4 cache lines FIFO <= 1
cache line
FIFO >= 4
cache lines
Read Line
xx 01
x Read Multiple
10 xx 1 Read 4 cache lines FIFO <= 2
cache lines
FIFO >= 4
cache lines
Read Line
xx 10
x Read Multiple
11 xx 1 Read 4 cache lines FIFO <= 3
cache lines
FIFO >= 4
cache lines
Read Line
xx 11
x Read Multiple
Table 2-4. PPC Master Read Ahead Options (Continued)
RXFT RMFT RAEN PCI Command
Initial
Read Size
Continuation
Subsequent
Read Size
Seitenansicht 70
1 2 ... 66 67 68 69 70 71 72 73 74 75 76 ... 353 354

Kommentare zu diesen Handbüchern

Keine Kommentare