ibm3206k0424 ETC-unknow, ibm3206k0424 Datasheet - Page 324

• Manufacturer Part Number: ibm3206k0424
• Description: Ibm Processor For Network Resources
• Manufacturer: ETC-unknow

IBM3206K0424
IBM Processor for Network Resources
Scatter/Cut Through Receive Processing
The scatter/cut through support is very versatile and easy to use. Scatter typically refers to scattering pages
from a contiguous IBM3206K0424 buffer into multiple non-contiguous host pages. Cut through refers to
moving contiguous data from IBM3206K0424 buffers into contiguous storage in host memory. The functions
are similar, and the terms scatter and cut through may be interchanged in the following text since cut through
is really a special case of scatter. The correct term is used when context requires it.
The scatter processing is performed by RXAAL along with RXQUE and DMAQS. The following items need to
be setup:
Once set up, the scatter mechanism is performed by RXAAL for the user. There is user intervention required
to process the packets when the scatter is complete, and for page recovery in error scenarios.
There are many options when setting up scatter, and the selection of the type of scatter processing to perform
depends on the users environment. The basic scatter mechanism will be described followed by a discussion
of the different options that can be used.
When packets are received and scattered, the following structure shows the main components of the
received packet:
General Layout of a Received Packet in Scatter Mode
struct ScatterRxPacket {
The DMA list is maintained immediately after the IBM3206K0424 packet header, and before the receive
packet data. For this reason, the user should allocate enough space between the packet header and the
packet data to accommodate a maximum-sized DMA list based on the maximum number of pages that could
be DMAed. The rxOffset field in the receive LCD is where this offset is specified. The maximum receive offset
is 256 bytes, which is specified with an rxOffset value of ’0’. The following is the layout of the DMA list:
Cell/Packet Re-assembly (REASM)
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};
• DMAQS should be setup and ready to run.
• RXQUE should be setup and ready to run. Each queue that is used should have the proper event size
• Page buffers or descriptors should be placed on the configured receive queues.
• The scatter configurations need to be set in the RXALL - Scatter/Cut Through Info Registers.
• The scatter flags need to be set in the RXALL - Scatter/Cut Through Flag Registers.
• Each LCD that is to use scatter, needs to have the ppMode field set to do scatter.
• A scatter configuration needs to be selected for each connection by setting the cutThruSel field in the
packetHeader; // Charm packet header
dmaList;
padbytes;
packetData;
selected, the direction should be set correctly, and timestamps and bcach advice should be disabled.
receive LCD.
// Scatter dma list
// Pad out to receive offset from lcd
// Actual receive packet
pnr25.chapt05.01
August 14, 2000
Preliminary