Configuration Parameters - UG1739

AMD Solarflare X4 Series Ethernet Adapter User Guide (UG1739)
Document ID
UG1739
Release Date
2025-10-24
Revision
1.0 English

The following table shows the available configuration parameters.

Important: Some of these values are interdependent. See the Constraints that follow.
Table 1. Configuration Parameters
Parameter Format Default Reset required Notes
port_mode string (enum) SKU or FW dependent Cold reboot The valid port modes are board-dependent. See Port Mode Values.

This setting determines the number of PFs (there is one PF per port).
firmware_variant string (enum) auto Cold reboot

Valid firmware variants are:

  • auto
  • full_featured
  • low_latency
  • dpdk
  • packed_stream

A value of “auto” means the firmware variant is chosen by the first driver to attach. If the driver does not give a preferred variant, default to full_featured.
vf_count integer 0-240 0 Cold reboot The number of VFs per PF.

VFs are not currently supported and this value must be 0.
msix_limit

integer 1-2048, must be power of two

 Max possible based on number of PFs/VFs Cold reboot Number of MSIX vectors per PF.
vf_msix_limit integer 1-128, must be power of two 1 Cold reboot

Number of MSIX vectors per VF.
vi_count

integer 2-8192

 8192 Cold reboot Number of VIs available on the whole system (the total across both instances of the Enterprise datapath).
rx_dc_size integer 8-128, must be power of two 64 Cold reboot RX descriptor cache size per VI.
tx_dc_size integer 8-128, must be power of two 16 Cold reboot TX descriptor size per VI.
rx_event_merge_timeout integer 0-100000 1500 None RX event merge timeout in ns.
rx_event_merge_max_events integer 0-15 15 None Maximum number of RX events that can be merged. A value of 0 disables RX event merging.
tx_event_merge_timeout integer 0-100000 1400 None TX event merge timeout in ns.
tx_event_merge_qempty_timeout integer 0-100000 700 None Reduced TX event merge timeout in ns, used when the queue is empty.
tx_event_merge_max_events integer 0-15 15 None Maximum number of TX events that can be merged. A value of 0 disables TX event merging.

Port Mode Values

The port_mode values available for X4 series adapters are shown in the following tables:

Table 2. X4522 Port Modes
Description port_mode Value
Each SFP56 cage supports a single port at 1 GbE / 10 GbE / 25 GbE / 50 GbE [1x1/10/25/50G][1x1/10/25/50G]
Table 3. X4542 Port Modes
Description port_mode Value
Each QSFP56 cage supports a single port at 1 GbE / 10 GbE / 25 GbE / 40 GbE / 50 GbE / 100 GbE [1x1/10/25/40/50/100G][1x1/10/25/40/50/100G]
One QSFP56 cage supports four ports at 1 GbE / 10 GbE / 25 GbE, and the other QSFP56 cage is administratively shutdown and is assigned for future expansion [4x1/10/25G]

Constraints

The following constraints apply:

Note: There is one PF per port.
Total number of MSIX vectors
The total number of MSIX vectors across all PFs and VFs must not be more than 8192. So:

(number of PFs) × (msix_limit + (vf_count × vf_msix_limit)) ≤ 8192

Total descriptor cache size
The total descriptor cache size must not be more than 655360. So:

vi_count × (rx_dc_size + tx_dc_size) ≤ 655360

The defaults for these parameters fill the whole cache, so if you increase one of these parameters you must decrease another.