BIOS preventing access to QPI performance counters

Are you experiencing issues with accessing the performance counters to measure QPI traffic on Intel Xeon processors E5 family? For examples, you might run into the following error message when you try to execute Intel Performance Counter Monitor (Intel PCM) on such a system:

ERROR: QPI LL counter programming seems not to work. Q_P0_PCI_PMON_BOX_CTL=0xffffffff

       Please see BIOS options to enable the export of performance monitoring devices.

The explanation is that the BIOS is hiding this device from you and tools like Intel PCM can therefore not access the required registers. Please check if there is an option available in your BIOS to enable the access. Since there is no special device driver available, Windows users will see a unsupported device as soon as they enable the option.

In case such an option is not available in the BIOS, please verify if a newer BIOS is available. Otherwise, you might need to contact the system vendor and ask for a BIOS with an option to enable access to these registers. The process of enabling the PCI config register access for QPI performance monitoring has recently been documented in in section 7.5.56 of the IntelR XeonR Processor E5-1600/2400/2600/4600 Product Families and IntelR XeonR Processor E5-1600/2400/2600/4600 V2 Product Families BIOS Specification Update, rev 1.1.2 (Bios Writers guide). Passing this information on to your system vendor will help the system vendor to service your request.