One recurring error on Debian systems is that the default perf_event_paranoid
setting disables the perf_event interface for user-space.
Check the current level and point the user to the file.
gdb/
* nat/linux-btrace.c (diagnose_perf_event_open_fail): New.
(linux_enable_pt, linux_enable_bts): Call
diagnose_perf_event_open_fail.