Descriptor RingsBCM5718 Programmer’s Guide
Broadcom®
January 29, 2016 • 5718-PG108-R Page 73
Send Rings
The controller devices covered in this document support only one host based Send Ring.
The Send Ring Producer Index is incremented by host software to add descriptors to the Send Ring (see
Figure 12 on page 74). By adding descriptors to the ring, the device is instructed to transmit packets that are
composed of the buffers pointed to by the descriptors. A single transmit packet may be composed of multiple
buffers that are pointed to by multiple send descriptors. The maximum number of send descriptors for a single
packet is (0.75)*(ring size).
2
Host Address High 0x2530 0x2520 0x220
Host Address Low 0x2534 0x2524 0x224
Max Length/Flag 0x2538 0x2528 0x228
NIC Address 0x253C 0x252C 0x22C
3
Host Address High 0x2550 0x2540 0x230
Host Address Low 0x2554 0x2544 0x234
Max Length/Flag 0x2558 0x2548 0x238
NIC Address 0x255C 0x254C 0x23C
4 Host Address High 0x2570 0x2560 0x240
..... ..... ..... ..... .....
16
Host Address High 0x26F0 0x26E0 0x300
Host Address Low 0x26F4 0x26E4 0x304
Max Length/Flag 0x26F8 0x26E8 0x308
NIC Address 0x26FC 0x26EC 0x30C
Note: [0x2450 .. 0x245C] and [0x2440 .. 0x244C] are legacy RCB addresses and are being assigned
to VRQ Ring# 0.
Note: The Return Ring RCBs are Memory Mapped. Memory Address [0x200 .. 0x23C] are legacy
Return Ring RCB addresses and are being assigned to VRQ Return Ring# 0 through Ring# 3
Table 7: High Priority Mail Box Registers for VRQ Rings (Cont.)
VRQ # Register Name
Standard Ring RCB
Register Address
Jumbo Ring RCB
Register Address
Return Ring RCB Register
Address (**)
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