--- a/docs/man3/libpfm_intel_atom.3
+++ b/docs/man3/libpfm_intel_atom.3
@@ -1,4 +1,4 @@
-.TH LIBPFM 3  "September, 2009" "" "Linux Programmer's Manual"
+.TH LIBPFM 4  "September, 2009" "" "Linux Programmer's Manual"
 .SH NAME
 libpfm_intel_atom - support for Intel Atom processors
 .SH SYNOPSIS
@@ -15,12 +15,10 @@
 The following modifiers are supported on Intel Atom processors:
 .TP
 .B u
-Measure at user level which includes privilege levels 1, 2, 3. This corresponds to \fBPFM_PLM3\fR.
-This is a boolean modifier.
+Measure at user level which includes privilege levels 1, 2, 3. This is a boolean modifier.
 .TP
 .B k
-Measure at kernel level which includes privilege level 0. This corresponds to \fBPFM_PLM0\fR.
-This is a boolean modifier.
+Measure at kernel level which includes privilege level 0. This is a boolean modifier.
 .TP
 .B i
 Invert the meaning of the event. The counter will now count cycles in which the event is \fBnot\fR
@@ -36,6 +34,10 @@
 .TP
 .B t
 Measure on both threads at the same time assuming hyper-threading is enabled. This is a boolean modifier.
+
+.SH ENVIRONMENT VARIABLES
+It is possible to force activation of the Intel Atom support using the \fBLIBPFM_FORCE_PMU\fR variable.
+The PMU name, atom, must be passed. No additional options are supported.
 .SH AUTHORS
 .nf
 Stephane Eranian <eranian@gmail.com>