fexecve.3: Add some detail on the glibc implementation of fexecve() via execveat(2)

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>

diff --git a/man3/fexecve.3 b/man3/fexecve.3
index 3ab39f9e47add1a562ecc0c7d63d9f7fc93c893c..25cf049dcf61d36951a1048d9d39b098aafdced0 100644 (file)
--- a/man3/fexecve.3
+++ b/man3/fexecve.3
@@ -112,18 +112,22 @@ This function is not specified in POSIX.1-2001,
 and is not widely available on other systems.
 It is specified in POSIX.1-2008.
 .SH NOTES
-On Linux,
+On Linux with glibc versions 2.26 and earlier,
 .BR fexecve ()
-was implemented using the
+is implemented using the
 .BR proc (5)
 filesystem, so
 .I /proc
-needed to be mounted and available at the time of the call.
+needs to be mounted and available at the time of the call.
 Since glibc 2.27,
 .\" glibc commit 43ffc53a352a67672210c9dd4959f6c6b7407e60
-it is implemented using
+if the underlying kernel supports the
 .BR execveat (2)
-instead.
+system call, then
+.BR fexecve ()
+is implemented using that system call, with the benefit that
+.IR /proc
+does not need to be mounted.
 .PP
 The idea behind
 .BR fexecve ()