perf open with "PERF_SAMPLE_REGS_USER" failing

Hi, I am running following code where I am configuring an intel PEBS device with "PERF_SAMPLE_REGS_USER" on a sky lake machine (function initPEBS). Upon "perf_event_open" it returns with "Invalid argument"(22) error. I can configure without "PERF_SAMPLE_REGS_USER" and get sample events. I am on kernel version: 5.2.2 . Any idea what could be the issue? https://gist.github.com/proywm/36561da2a99f4ada8eafe8bdbdf3bbb7 -- Probir Roy