diff --git a/tools/build/checkstyle9.pl b/tools/build/checkstyle9.pl
index aadf6ee152c5..d2c6ea77868d 100755
--- a/tools/build/checkstyle9.pl
+++ b/tools/build/checkstyle9.pl
@@ -170,8 +170,6 @@ if ($color =~ /^always$/i) {
 
 my $dbg_values = 0;
 my $dbg_possible = 0;
-my $dbg_type = 0;
-my $dbg_attr = 0;
 my $dbg_adv_dcs = 0;
 my $dbg_adv_checking = 0;
 my $dbg_adv_apw = 0;
@@ -1436,17 +1434,12 @@ sub process {
 			}
 		}
 
-# Only allow Python 3 interpreter
-		if ($realline == 1 &&
-			$line =~ /^\+#!\ *\/usr\/bin\/(?:env )?python$/) {
-			ERROR("please use python3 interpreter\n" . $herecurr);
-		}
-
 # Accept git diff extended headers as valid patches
 		if ($line =~ /^(?:rename|copy) (?:from|to) [\w\/\.\-]+\s*$/) {
 			$is_patch = 1;
 		}
 
+# Filter out bad email addresses.
 		if ($line =~ /^(Author|From): .*noreply.*/) {
 		    ERROR("Real email adress is needed\n" . $herecurr);
 		}
@@ -1512,9 +1505,6 @@ sub process {
 # ignore non-hunk lines and lines being removed
 		next if (!$hunk_line || $line =~ /^-/);
 
-# ignore files that are being periodically imported from Linux
-		next if ($realfile =~ /^(linux-headers|include\/standard-headers)\//);
-
 #trailing whitespace
 		if ($line =~ /^\+.*\015/) {
 			my $herevet = "$here\n" . cat_vet($rawline) . "\n";
@@ -1536,26 +1526,6 @@ sub process {
 			$rpt_cleaners = 1;
 		}
 
-# checks for trace-events files
-		if ($realfile =~ /trace-events$/ && $line =~ /^\+/) {
-			if ($rawline =~ /%[-+ 0]*#/) {
-				ERROR("Don't use '#' flag of printf format ('%#') in " .
-				      "trace-events, use '0x' prefix instead\n" . $herecurr);
-			} else {
-				my $hex =
-					qr/%[-+ *.0-9]*([hljztL]|ll|hh)?(x|X|"\s*PRI[xX][^"]*"?)/;
-
-				# don't consider groups splitted by [.:/ ], like 2A.20:12ab
-				my $tmpline = $rawline;
-				$tmpline =~ s/($hex[.:\/ ])+$hex//g;
-
-				if ($tmpline =~ /(?<!0x)$hex/) {
-					ERROR("Hex numbers must be prefixed with '0x'\n" .
-					      $herecurr);
-				}
-			}
-		}
-
 # check we are in a valid source file if not then ignore this hunk
 		next if ($realfile !~ /$SrcFile/);
 
@@ -1584,7 +1554,7 @@ sub process {
 		}
 
 # check for RCS/CVS revision markers
-		if ($rawline =~ /^\+.*\$(Revision|Log|Id)(?:\$|\b)/) {
+		if ($rawline =~ /^\+.*\$(FreeBSD|Revision|Log|Id)(?:\$|\b)/) {
 			ERROR("CVS style keyword markers, these will _not_ be updated\n". $herecurr);
 		}
 
@@ -1886,25 +1856,6 @@ sub process {
 #ignore lines not being added
 		if ($line=~/^[^\+]/) {next;}
 
-# TEST: allow direct testing of the type matcher.
-		if ($dbg_type) {
-			if ($line =~ /^.\s*$Declare\s*$/) {
-				ERROR("TEST: is type\n" . $herecurr);
-			} elsif ($dbg_type > 1 && $line =~ /^.+($Declare)/) {
-				ERROR("TEST: is not type ($1 is)\n". $herecurr);
-			}
-			next;
-		}
-# TEST: allow direct testing of the attribute matcher.
-		if ($dbg_attr) {
-			if ($line =~ /^.\s*$Modifier\s*$/) {
-				ERROR("TEST: is attr\n" . $herecurr);
-			} elsif ($dbg_attr > 1 && $line =~ /^.+($Modifier)/) {
-				ERROR("TEST: is not attr ($1 is)\n". $herecurr);
-			}
-			next;
-		}
-
 # check for initialisation to aggregates open brace on the next line
 		if ($line =~ /^.\s*\{/ &&
 		    $prevline =~ /(?:^|[^=])=\s*$/) {
@@ -1928,17 +1879,6 @@ sub process {
 		$line =~ s@//.*@@;
 		$opline =~ s@//.*@@;
 
-# check for global initialisers.
-#		if ($line =~ /^.$Type\s*$Ident\s*(?:\s+$Modifier)*\s*=\s*(0|NULL|false)\s*;/) {
-#			ERROR("do not initialise globals to 0 or NULL\n" .
-#				$herecurr);
-#		}
-# check for static initialisers.
-#		if ($line =~ /\bstatic\s.*=\s*(0|NULL|false)\s*;/) {
-#			ERROR("do not initialise statics to 0 or NULL\n" .
-#				$herecurr);
-#		}
-
 # * goes on variable not on type
 		# (char*[ const])
 		if ($line =~ m{\($NonptrType(\s*(?:$Modifier\b\s*|\*\s*)+)\)}) {