Intel® Stratix® 10 Hard Processor System Technical Reference Manual

ID 683222
Date 11/28/2022
Public

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17.6.3.2.3.2. Receive Descriptor Field 3 (RDES3)

Table 177.  Receive Descriptor Field 3 (RDES3)

Bit

Description

31:0

Buffer 2 Address Pointer (Next Descriptor Address)

These bits indicate the physical address of Buffer 2 when a descriptor ring structure is used. If the Second Address Chained (RDES1[14]) bit in Receive Descriptor Field 1 (RDES1) is set, this address contains the pointer to the physical memory where the Next descriptor is present.

If RDES1[14], in the Receive Descriptor Field 1 (RDES1) is set, the buffer (Next descriptor) address pointer must be bus width-aligned (RDES3[1:0] = 0. LSBs are ignored internally.) However, when RDES1[14] in the Receive Descriptor Field 1 (RDES1) is cleared, there are no limitations on the RDES3 value, except for the following condition: the DMA uses the value programmed in RDES3 [1:0] for its buffer address generation when the RDES3 value is used to store the start of frame. The DMA ignores RDES3 [1:0] if the address pointer is to a buffer where the middle or last part of the frame is stored.