Issue Accessing 64-bit Prefetchable BARs on PCIe Devices: Configuration and Troubleshooting Guidance

[osmanyagci]

Hi,

I’m currently working with a PCIe-based system where we have several devices that require 64-bit prefetchable addresses for their Base Address Registers (BARs). We have assigned 64-bit addresses to these BARs as per the PCIe specification. 

However, we are encountering issues accessing these BARs.

Problem Details:

CPU: XEON-D

Configuration: We have configured the BARs to use 64-bit prefetchable addresses. The addresses are within the expected range and correctly aligned (The address range configured for 64-bit prefetchable address is above TOUUD in our system).

Issue Description: Despite assigning the 64-bit addresses, we are unable to access these BARs. Attempts to read or write to these addresses result in errors or no response.

Questions:

Are there specific requirements or configurations that need to be met for 64-bit prefetchable BARs to function correctly?

Could there be hardware or BIOS settings that might prevent access to 64-bit BARs?

Are there known issues or limitations with certain Intel chipsets or processors regarding 64-bit prefetchable BARs?

What additional diagnostics can we perform to identify the root cause of this issue?

Any guidance or suggestions on how to resolve this problem would be greatly appreciated.

Thank you in advance for your assistance.

Best regards,

Osman Yağcı

[osmanyagci]

A little update to the question;

Our CPU is Xeon D-1559.

[CarlosAM_INTEL]

Hello, @osmanyagci:

Thank you for contacting Intel Embedded Community.

The Intel® Xeon® Processor D-1559 is a Broadwell-DE processor, as you may confirm in the following website:

https://www.intel.com/content/www/us/en/products/sku/93352/intel-xeon-processor-d1559-18m-cache-1-50-ghz/specifications.html 

We need to clarify that the Broadwell-DE processors have been discontinued and are no longer supported, as you may verify on the following website:

https://www.intel.com/content/www/us/en/support/articles/000022396/processors.html 

However, you may find the available documentation for the Broadwell-DE processors on the following website:

https://www.intel.com/content/www/us/en/products/platforms/details/broadwell-de/docs.html

Best regards,
@CarlosAM_INTEL.