Can anyone confirm that the way to identify if a linux system has pcid support is to check /proc/cpuinfo? Or is that merely to identify if the hw supports it, independent of the kernel support?

I checked two ubuntu servers, one 14.04, the other 16.04, both have it. Which seems odd given the claim that it's only been added recently to the kernel.

Also I see nothing showing up in dmesg, no config option and no proc interface on any system.