Forum Discussion
Occasional ContributorStratix 10 PCIe SR-IOV
Hi All,
I am using the PCIe SR-IOV IP for Stratix 10. I see that Virtual Functions default to a Maximum Read Request and Max Payload Size of 128B. Is this a limitation of the actual specification ? If not can somebody please walk me through what is necessary to change this. I cannot find this information anywhere in user guide and documentation.
Thank you!
6 Replies
SengKok_L_IntelRegular Contributor
Hi,
System software can control the max read request & Max Payload size from the Device Control Register. You may refer to the Table 66 for the address offset.
https://www.intel.com/content/dam/www/programmable/us/en/pdfs/literature/ug/ug_s10_pcie_avst.pdf
Regards -SK
agulaHi,
There is no max read request or payload settings for the VF in Table 66.
The only MPS and MRRS settings is the one for the PF. The PF settings are 256B and 512B respectively but they are not inherited by the VF.
- SengKok_L_Intel
Hi,
The Max. Payload size and Max. Read Request Size is configurable via the "Control and Status Registers".
Regards -SK
- agula
Table 71 shows that VF Control and Status Registers and it does not show anything regarding Max Payload Size or Max Read Request Size.
The PF control and status registers have these parameters, but the VF does not inherit them. They default to 128B.
- SengKok_L_Intel
Hi,
I apologize for the confusion. There is no max payload size setting specifically for the VF. As per the PCIe spec, the max payload size in the PF device control register setting applies to the VF. Do you able to send the same payload size (for example 512 bytes) for both PF and VF (under the same PF)?
Regards -SK
- SengKok_L_Intel
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