Ethernet Controller x710: Increasing the max size of the RX descriptor ring

[pjf]

The documentation of the 700-series Ethernet  controller indicates that the Receive Queue Length can be up to (8192 - 32) or 8160.  Section 8.3.3.2.2 Receive Queue Context in FPM32464_710_Series_Datasheet_v_4_1.pdf

However, the i40e Linux driver for the X710 Ethernet controller in the 6.6. kernel has a maximum size of 4096.  

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/net/ethernet/intel/i40e/i40e.h?h=v6.6-rc6#n52

I'm mainly interested in hearing from Intel support if they have any concerns with increasing the maximum from 4096 to 8160 for the X710 controller? If not, we can push this change upstream.  

[pjf]

I have the common datasheet for X710, XXV710, and XL710  which indicate 8160.  The datasheets for the V710 and X722 aren't available for download on the Intel site: https://ark.intel.com/content/www/us/en/ark/products/202627.html but if we can confirm that V710 and X722 also support 8160, we can make a generic change to the driver.  

[Diego_INTEL]

Hello @pjf,

Thank you for contacting Intel Embedded Community.

I looked internally and if the max value is set greater than 4096, the driver may discard the change and set it to the default value, so, you can do the change, but if the driver returns to a default value, then there is a limitation and it may not be possible.

Also, here you may check the documentation available for the x710, some documents are private but you will see the ones that are public.

https://www.intel.com/content/www/us/en/products/details/ethernet/700-controllers/x710-controllers/docs.html?q=data&s=Relevancy

And here is the datasheet, just sharing in case you want it from an official source.

https://www.intel.com/content/www/us/en/content-details/332464/intel-ethernet-controller-x710-xxv710-xl710-datasheet.html?DocID=332464

Best regards,

@Diego_INTEL