scripts/namespace.pl - linux/kernel/git/klassert/ipsec-next - Git at Google

 #!/usr/bin/perl -w
 #
 #	namespace.pl.  Mon Aug 30 2004
 #
 #	Perform a name space analysis on the linux kernel.
 #
 #	Copyright Keith Owens <kaos@ocs.com.au>.  GPL.
 #
 #	Invoke by changing directory to the top of the kernel object
 #	tree then namespace.pl, no parameters.
 #
 #	Tuned for 2.1.x kernels with the new module handling, it will
 #	work with 2.0 kernels as well.
 #
 #	Last change 2.6.9-rc1, adding support for separate source and object
 #	trees.
 #
 #	The source must be compiled/assembled first, the object files
 #	are the primary input to this script.  Incomplete or missing
 #	objects will result in a flawed analysis.  Compile both vmlinux
 #	and modules.
 #
 #	Even with complete objects, treat the result of the analysis
 #	with caution.  Some external references are only used by
 #	certain architectures, others with certain combinations of
 #	configuration parameters.  Ideally the source should include
 #	something like
 #
 #	#ifndef CONFIG_...
 #	static
 #	#endif
 #	symbol_definition;
 #
 #	so the symbols are defined as static unless a particular
 #	CONFIG_... requires it to be external.
 #
 #	A symbol that is suffixed with '(export only)' has these properties
 #
 #	* It is global.
 #	* It is marked EXPORT_SYMBOL or EXPORT_SYMBOL_GPL, either in the same
 #	  source file or a different source file.
 #	* Given the current .config, nothing uses the symbol.
 #
 #	The symbol is a candidate for conversion to static, plus removal of the
 #	export.  But be careful that a different .config might use the symbol.
 #
 #
 #	Name space analysis and cleanup is an iterative process.  You cannot
 #	expect to find all the problems in a single pass.
 #
 #	* Identify possibly unnecessary global declarations, verify that they
 #	  really are unnecessary and change them to static.
 #	* Compile and fix up gcc warnings about static, removing dead symbols
 #	  as necessary.
 #	* make clean and rebuild with different configs (especially
 #	  CONFIG_MODULES=n) to see which symbols are being defined when the
 #	  config does not require them.  These symbols bloat the kernel object
 #	  for no good reason, which is frustrating for embedded systems.
 #	* Wrap config sensitive symbols in #ifdef CONFIG_foo, as long as the
 #	  code does not get too ugly.
 #	* Repeat the name space analysis until you can live with with the
 #	  result.
 #

 require 5;	# at least perl 5
 use strict;
 use File::Find;

 my $nm = "/usr/bin/nm -p";
 my $objdump = "/usr/bin/objdump -s -j .comment";
 my $srctree = "";
 my $objtree = "";
 $srctree = "$ENV{'srctree'}/" if (exists($ENV{'srctree'}));
 $objtree = "$ENV{'objtree'}/" if (exists($ENV{'objtree'}));

 if ($#ARGV != -1) {
 	print STDERR "usage: $0 takes no parameters\n";
 	die("giving up\n");
 }

 my %nmdata = ();	# nm data for each object
 my %def = ();		# all definitions for each name
 my %ksymtab = ();	# names that appear in __ksymtab_
 my %ref = ();		# $ref{$name} exists if there is a true external reference to $name
 my %export = ();	# $export{$name} exists if there is an EXPORT_... of $name

 &find(\&linux_objects, '.');	# find the objects and do_nm on them
 &list_multiply_defined();
 &resolve_external_references();
 &list_extra_externals();

 exit(0);

 sub linux_objects
 {
 	# Select objects, ignoring objects which are only created by
 	# merging other objects.  Also ignore all of modules, scripts
 	# and compressed.  Most conglomerate objects are handled by do_nm,
 	# this list only contains the special cases.  These include objects
 	# that are linked from just one other object and objects for which
 	# there is really no permanent source file.
 	my $basename = $_;
 	$_ = $File::Find::name;
 	s:^\./::;
 	if (/.*\.o$/ &&
 		! (
 		m:/built-in.o$:
 		|| m:arch/i386/kernel/vsyscall-syms.o$:
 		|| m:arch/ia64/ia32/ia32.o$:
 		|| m:arch/ia64/kernel/gate-syms.o$:
 		|| m:arch/ia64/lib/__divdi3.o$:
 		|| m:arch/ia64/lib/__divsi3.o$:
 		|| m:arch/ia64/lib/__moddi3.o$:
 		|| m:arch/ia64/lib/__modsi3.o$:
 		|| m:arch/ia64/lib/__udivdi3.o$:
 		|| m:arch/ia64/lib/__udivsi3.o$:
 		|| m:arch/ia64/lib/__umoddi3.o$:
 		|| m:arch/ia64/lib/__umodsi3.o$:
 		|| m:arch/ia64/scripts/check_gas_for_hint.o$:
 		|| m:arch/ia64/sn/kernel/xp.o$:
 		|| m:boot/bbootsect.o$:
 		|| m:boot/bsetup.o$:
 		|| m:/bootsect.o$:
 		|| m:/boot/setup.o$:
 		|| m:/compressed/:
 		|| m:drivers/cdrom/driver.o$:
 		|| m:drivers/char/drm/tdfx_drv.o$:
 		|| m:drivers/ide/ide-detect.o$:
 		|| m:drivers/ide/pci/idedriver-pci.o$:
 		|| m:drivers/media/media.o$:
 		|| m:drivers/scsi/sd_mod.o$:
 		|| m:drivers/video/video.o$:
 		|| m:fs/devpts/devpts.o$:
 		|| m:fs/exportfs/exportfs.o$:
 		|| m:fs/hugetlbfs/hugetlbfs.o$:
 		|| m:fs/msdos/msdos.o$:
 		|| m:fs/nls/nls.o$:
 		|| m:fs/ramfs/ramfs.o$:
 		|| m:fs/romfs/romfs.o$:
 		|| m:fs/vfat/vfat.o$:
 		|| m:init/mounts.o$:
 		|| m:^modules/:
 		|| m:net/netlink/netlink.o$:
 		|| m:net/sched/sched.o$:
 		|| m:/piggy.o$:
 		|| m:^scripts/:
 		|| m:sound/.*/snd-:
 		|| m:^.*/\.tmp_:
 		|| m:^\.tmp_:
 		|| m:/vmlinux-obj.o$:
 		)
 	) {
 		do_nm($basename, $_);
 	}
 	$_ = $basename;		# File::Find expects $_ untouched (undocumented)
 }

 sub do_nm
 {
 	my ($basename, $fullname) = @_;
 	my ($source, $type, $name);
 	if (! -e $basename) {
 		printf STDERR "$basename does not exist\n";
 		return;
 	}
 	if ($fullname !~ /\.o$/) {
 		printf STDERR "$fullname is not an object file\n";
 		return;
 	}
 	($source = $fullname) =~ s/\.o$//;
 	if (-e "$objtree$source.c" || -e "$objtree$source.S") {
 		$source = "$objtree$source";
 	} else {
 		$source = "$srctree$source";
 	}
 	if (! -e "$source.c" && ! -e "$source.S") {
 		# No obvious source, exclude the object if it is conglomerate
 		if (! open(OBJDUMPDATA, "$objdump $basename|")) {
 			printf STDERR "$objdump $fullname failed $!\n";
 			return;
 		}
 		my $comment;
 		while (<OBJDUMPDATA>) {
 			chomp();
 			if (/^In archive/) {
 				# Archives are always conglomerate
 				$comment = "GCC:GCC:";
 				last;
 			}
 			next if (! /^[ 0-9a-f]{5,} /);
 			$comment .= substr($_, 43);
 		}
 		close(OBJDUMPDATA);
 		if (!defined($comment) || $comment !~ /GCC\:.*GCC\:/m) {
 			printf STDERR "No source file found for $fullname\n";
 		}
 		return;
 	}
 	if (! open(NMDATA, "$nm $basename|")) {
 		printf STDERR "$nm $fullname failed $!\n";
 		return;
 	}
 	my @nmdata;
 	while (<NMDATA>) {
 		chop;
 		($type, $name) = (split(/ +/, $_, 3))[1..2];
 		# Expected types
 		# A absolute symbol
 		# B weak external reference to data that has been resolved
 		# C global variable, uninitialised
 		# D global variable, initialised
 		# G global variable, initialised, small data section
 		# R global array, initialised
 		# S global variable, uninitialised, small bss
 		# T global label/procedure
 		# U external reference
 		# W weak external reference to text that has been resolved
 		# a assembler equate
 		# b static variable, uninitialised
 		# d static variable, initialised
 		# g static variable, initialised, small data section
 		# r static array, initialised
 		# s static variable, uninitialised, small bss
 		# t static label/procedures
 		# w weak external reference to text that has not been resolved
 		# ? undefined type, used a lot by modules
 		if ($type !~ /^[ABCDGRSTUWabdgrstw?]$/) {
 			printf STDERR "nm output for $fullname contains unknown type '$_'\n";
 		}
 		elsif ($name =~ /\./) {
 			# name with '.' is local static
 		}
 		else {
 			$type = 'R' if ($type eq '?');	# binutils replaced ? with R at one point
 			# binutils keeps changing the type for exported symbols, force it to R
 			$type = 'R' if ($name =~ /^__ksymtab/ || $name =~ /^__kstrtab/);
 			$name =~ s/_R[a-f0-9]{8}$//;	# module versions adds this
 			if ($type =~ /[ABCDGRSTW]/ &&
 				$name ne 'init_module' &&
 				$name ne 'cleanup_module' &&
 				$name ne 'Using_Versions' &&
 				$name !~ /^Version_[0-9]+$/ &&
 				$name !~ /^__parm_/ &&
 				$name !~ /^__kstrtab/ &&
 				$name !~ /^__ksymtab/ &&
 				$name !~ /^__kcrctab_/ &&
 				$name !~ /^__exitcall_/ &&
 				$name !~ /^__initcall_/ &&
 				$name !~ /^__kdb_initcall_/ &&
 				$name !~ /^__kdb_exitcall_/ &&
 				$name !~ /^__module_/ &&
 				$name !~ /^__mod_/ &&
 				$name !~ /^__crc_/ &&
 				$name ne '__this_module' &&
 				$name ne 'kernel_version') {
 				if (!exists($def{$name})) {
 					$def{$name} = [];
 				}
 				push(@{$def{$name}}, $fullname);
 			}
 			push(@nmdata, "$type $name");
 			if ($name =~ /^__ksymtab_/) {
 				$name = substr($name, 10);
 				if (!exists($ksymtab{$name})) {
 					$ksymtab{$name} = [];
 				}
 				push(@{$ksymtab{$name}}, $fullname);
 			}
 		}
 	}
 	close(NMDATA);
 	if ($#nmdata < 0) {
 		if (
 			$fullname ne "lib/brlock.o"
 			&& $fullname ne "lib/dec_and_lock.o"
 			&& $fullname ne "fs/xfs/xfs_macros.o"
 			&& $fullname ne "drivers/ide/ide-probe-mini.o"
 			&& $fullname ne "usr/initramfs_data.o"
 			&& $fullname ne "drivers/acpi/executer/exdump.o"
 			&& $fullname ne "drivers/acpi/resources/rsdump.o"
 			&& $fullname ne "drivers/acpi/namespace/nsdumpdv.o"
 			&& $fullname ne "drivers/acpi/namespace/nsdump.o"
 			&& $fullname ne "arch/ia64/sn/kernel/sn2/io.o"
 			&& $fullname ne "arch/ia64/kernel/gate-data.o"
 			&& $fullname ne "drivers/ieee1394/oui.o"
 			&& $fullname ne "security/capability.o"
 			&& $fullname ne "sound/core/wrappers.o"
 			&& $fullname ne "fs/ntfs/sysctl.o"
 			&& $fullname ne "fs/jfs/jfs_debug.o"
 		) {
 			printf "No nm data for $fullname\n";
 		}
 		return;
 	}
 	$nmdata{$fullname} = \@nmdata;
 }

 sub drop_def
 {
 	my ($object, $name) = @_;
 	my $nmdata = $nmdata{$object};
 	my ($i, $j);
 	for ($i = 0; $i <= $#{$nmdata}; ++$i) {
 		if ($name eq (split(' ', $nmdata->[$i], 2))[1]) {
 			splice(@{$nmdata{$object}}, $i, 1);
 			my $def = $def{$name};
 			for ($j = 0; $j < $#{$def{$name}}; ++$j) {
 				if ($def{$name}[$j] eq $object) {
 					splice(@{$def{$name}}, $j, 1);
 				}
 			}
 			last;
 		}
 	}
 }

 sub list_multiply_defined
 {
 	my ($name, $module);
 	foreach $name (keys(%def)) {
 		if ($#{$def{$name}} > 0) {
 			# Special case for cond_syscall
 			if ($#{$def{$name}} == 1 && $name =~ /^sys_/ &&
 			    ($def{$name}[0] eq "kernel/sys.o" ||
 			     $def{$name}[1] eq "kernel/sys.o")) {
 				&drop_def("kernel/sys.o", $name);
 				next;
 			}
 			# Special case for i386 entry code
 			if ($#{$def{$name}} == 1 && $name =~ /^__kernel_/ &&
 			    $def{$name}[0] eq "arch/i386/kernel/vsyscall-int80.o" &&
 			    $def{$name}[1] eq "arch/i386/kernel/vsyscall-sysenter.o") {
 				&drop_def("arch/i386/kernel/vsyscall-sysenter.o", $name);
 				next;
 			}
 			printf "$name is multiply defined in :-\n";
 			foreach $module (@{$def{$name}}) {
 				printf "\t$module\n";
 			}
 		}
 	}
 }

 sub resolve_external_references
 {
 	my ($object, $type, $name, $i, $j, $kstrtab, $ksymtab, $export);
 	printf "\n";
 	foreach $object (keys(%nmdata)) {
 		my $nmdata = $nmdata{$object};
 		for ($i = 0; $i <= $#{$nmdata}; ++$i) {
 			($type, $name) = split(' ', $nmdata->[$i], 2);
 			if ($type eq "U" || $type eq "w") {
 				if (exists($def{$name}) || exists($ksymtab{$name})) {
 					# add the owning object to the nmdata
 					$nmdata->[$i] = "$type $name $object";
 					# only count as a reference if it is not EXPORT_...
 					$kstrtab = "R __kstrtab_$name";
 					$ksymtab = "R __ksymtab_$name";
 					$export = 0;
 					for ($j = 0; $j <= $#{$nmdata}; ++$j) {
 						if ($nmdata->[$j] eq $kstrtab ||
 						    $nmdata->[$j] eq $ksymtab) {
 							$export = 1;
 							last;
 						}
 					}
 					if ($export) {
 						$export{$name} = "";
 					}
 					else {
 						$ref{$name} = ""
 					}
 				}
 				elsif (    $name ne "mod_use_count_"
 					&& $name ne "__initramfs_end"
 					&& $name ne "__initramfs_start"
 					&& $name ne "_einittext"
 					&& $name ne "_sinittext"
 					&& $name ne "kallsyms_names"
 					&& $name ne "kallsyms_num_syms"
 					&& $name ne "kallsyms_addresses"
 					&& $name ne "__this_module"
 					&& $name ne "_etext"
 					&& $name ne "_edata"
 					&& $name ne "_end"
 					&& $name ne "__bss_start"
 					&& $name ne "_text"
 					&& $name ne "_stext"
 					&& $name ne "__gp"
 					&& $name ne "ia64_unw_start"
 					&& $name ne "ia64_unw_end"
 					&& $name ne "__init_begin"
 					&& $name ne "__init_end"
 					&& $name ne "__bss_stop"
 					&& $name ne "__nosave_begin"
 					&& $name ne "__nosave_end"
 					&& $name ne "pg0"
 					&& $name ne "__module_text_address"
 					&& $name !~ /^__sched_text_/
 					&& $name !~ /^__start_/
 					&& $name !~ /^__end_/
 					&& $name !~ /^__stop_/
 					&& $name !~ /^__scheduling_functions_.*_here/
 					&& $name !~ /^__.*initcall_/
 					&& $name !~ /^__.*per_cpu_start/
 					&& $name !~ /^__.*per_cpu_end/
 					&& $name !~ /^__alt_instructions/
 					&& $name !~ /^__setup_/
 					&& $name !~ /^jiffies/
 					&& $name !~ /^__mod_timer/
 					&& $name !~ /^__mod_page_state/
 					&& $name !~ /^init_module/
 					&& $name !~ /^cleanup_module/
 				) {
 					printf "Cannot resolve ";
 					printf "weak " if ($type eq "w");
 					printf "reference to $name from $object\n";
 				}
 			}
 		}
 	}
 }

 sub list_extra_externals
 {
 	my %noref = ();
 	my ($name, @module, $module, $export);
 	foreach $name (keys(%def)) {
 		if (! exists($ref{$name})) {
 			@module = @{$def{$name}};
 			foreach $module (@module) {
 				if (! exists($noref{$module})) {
 					$noref{$module} = [];
 				}
 				push(@{$noref{$module}}, $name);
 			}
 		}
 	}
 	if (%noref) {
 		printf "\nExternally defined symbols with no external references\n";
 		foreach $module (sort(keys(%noref))) {
 			printf "  $module\n";
 			foreach (sort(@{$noref{$module}})) {
 				if (exists($export{$_})) {
 					$export = " (export only)";
 				}
 				else {
 					$export = "";
 				}
 				printf "    $_$export\n";
 			}
 		}
 	}
 }
	#!/usr/bin/perl -w
	#
	# namespace.pl. Mon Aug 30 2004
	#
	# Perform a name space analysis on the linux kernel.
	#
	# Copyright Keith Owens <kaos@ocs.com.au>. GPL.
	#
	# Invoke by changing directory to the top of the kernel object
	# tree then namespace.pl, no parameters.
	#
	# Tuned for 2.1.x kernels with the new module handling, it will
	# work with 2.0 kernels as well.
	#
	# Last change 2.6.9-rc1, adding support for separate source and object
	# trees.
	#
	# The source must be compiled/assembled first, the object files
	# are the primary input to this script. Incomplete or missing
	# objects will result in a flawed analysis. Compile both vmlinux
	# and modules.
	#
	# Even with complete objects, treat the result of the analysis
	# with caution. Some external references are only used by
	# certain architectures, others with certain combinations of
	# configuration parameters. Ideally the source should include
	# something like
	#
	# #ifndef CONFIG_...
	# static
	# #endif
	# symbol_definition;
	#
	# so the symbols are defined as static unless a particular
	# CONFIG_... requires it to be external.
	#
	# A symbol that is suffixed with '(export only)' has these properties
	#
	# * It is global.
	# * It is marked EXPORT_SYMBOL or EXPORT_SYMBOL_GPL, either in the same
	# source file or a different source file.
	# * Given the current .config, nothing uses the symbol.
	#
	# The symbol is a candidate for conversion to static, plus removal of the
	# export. But be careful that a different .config might use the symbol.
	#
	#
	# Name space analysis and cleanup is an iterative process. You cannot
	# expect to find all the problems in a single pass.
	#
	# * Identify possibly unnecessary global declarations, verify that they
	# really are unnecessary and change them to static.
	# * Compile and fix up gcc warnings about static, removing dead symbols
	# as necessary.
	# * make clean and rebuild with different configs (especially
	# CONFIG_MODULES=n) to see which symbols are being defined when the
	# config does not require them. These symbols bloat the kernel object
	# for no good reason, which is frustrating for embedded systems.
	# * Wrap config sensitive symbols in #ifdef CONFIG_foo, as long as the
	# code does not get too ugly.
	# * Repeat the name space analysis until you can live with with the
	# result.
	#

	require 5; # at least perl 5
	use strict;
	use File::Find;

	my $nm = "/usr/bin/nm -p";
	my $objdump = "/usr/bin/objdump -s -j .comment";
	my $srctree = "";
	my $objtree = "";
	$srctree = "$ENV{'srctree'}/" if (exists($ENV{'srctree'}));
	$objtree = "$ENV{'objtree'}/" if (exists($ENV{'objtree'}));

	if ($#ARGV != -1) {
	print STDERR "usage: $0 takes no parameters\n";
	die("giving up\n");
	}

	my %nmdata = (); # nm data for each object
	my %def = (); # all definitions for each name
	my %ksymtab = (); # names that appear in __ksymtab_
	my %ref = (); # $ref{$name} exists if there is a true external reference to $name
	my %export = (); # $export{$name} exists if there is an EXPORT_... of $name

	&find(\&linux_objects, '.'); # find the objects and do_nm on them
	&list_multiply_defined();
	&resolve_external_references();
	&list_extra_externals();

	exit(0);

	sub linux_objects
	{
	# Select objects, ignoring objects which are only created by
	# merging other objects. Also ignore all of modules, scripts
	# and compressed. Most conglomerate objects are handled by do_nm,
	# this list only contains the special cases. These include objects
	# that are linked from just one other object and objects for which
	# there is really no permanent source file.
	my $basename = $_;
	$_ = $File::Find::name;
	s:^\./::;
	if (/.*\.o$/ &&
	! (
	m:/built-in.o$:
	\|\| m:arch/i386/kernel/vsyscall-syms.o$:
	\|\| m:arch/ia64/ia32/ia32.o$:
	\|\| m:arch/ia64/kernel/gate-syms.o$:
	\|\| m:arch/ia64/lib/__divdi3.o$:
	\|\| m:arch/ia64/lib/__divsi3.o$:
	\|\| m:arch/ia64/lib/__moddi3.o$:
	\|\| m:arch/ia64/lib/__modsi3.o$:
	\|\| m:arch/ia64/lib/__udivdi3.o$:
	\|\| m:arch/ia64/lib/__udivsi3.o$:
	\|\| m:arch/ia64/lib/__umoddi3.o$:
	\|\| m:arch/ia64/lib/__umodsi3.o$:
	\|\| m:arch/ia64/scripts/check_gas_for_hint.o$:
	\|\| m:arch/ia64/sn/kernel/xp.o$:
	\|\| m:boot/bbootsect.o$:
	\|\| m:boot/bsetup.o$:
	\|\| m:/bootsect.o$:
	\|\| m:/boot/setup.o$:
	\|\| m:/compressed/:
	\|\| m:drivers/cdrom/driver.o$:
	\|\| m:drivers/char/drm/tdfx_drv.o$:
	\|\| m:drivers/ide/ide-detect.o$:
	\|\| m:drivers/ide/pci/idedriver-pci.o$:
	\|\| m:drivers/media/media.o$:
	\|\| m:drivers/scsi/sd_mod.o$:
	\|\| m:drivers/video/video.o$:
	\|\| m:fs/devpts/devpts.o$:
	\|\| m:fs/exportfs/exportfs.o$:
	\|\| m:fs/hugetlbfs/hugetlbfs.o$:
	\|\| m:fs/msdos/msdos.o$:
	\|\| m:fs/nls/nls.o$:
	\|\| m:fs/ramfs/ramfs.o$:
	\|\| m:fs/romfs/romfs.o$:
	\|\| m:fs/vfat/vfat.o$:
	\|\| m:init/mounts.o$:
	\|\| m:^modules/:
	\|\| m:net/netlink/netlink.o$:
	\|\| m:net/sched/sched.o$:
	\|\| m:/piggy.o$:
	\|\| m:^scripts/:
	\|\| m:sound/.*/snd-:
	\|\| m:^.*/\.tmp_:
	\|\| m:^\.tmp_:
	\|\| m:/vmlinux-obj.o$:
	)
	) {
	do_nm($basename, $_);
	}
	$_ = $basename; # File::Find expects $_ untouched (undocumented)
	}

	sub do_nm
	{
	my ($basename, $fullname) = @_;
	my ($source, $type, $name);
	if (! -e $basename) {
	printf STDERR "$basename does not exist\n";
	return;
	}
	if ($fullname !~ /\.o$/) {
	printf STDERR "$fullname is not an object file\n";
	return;
	}
	($source = $fullname) =~ s/\.o$//;
	if (-e "$objtree$source.c" \|\| -e "$objtree$source.S") {
	$source = "$objtree$source";
	} else {
	$source = "$srctree$source";
	}
	if (! -e "$source.c" && ! -e "$source.S") {
	# No obvious source, exclude the object if it is conglomerate
	if (! open(OBJDUMPDATA, "$objdump $basename\|")) {
	printf STDERR "$objdump $fullname failed $!\n";
	return;
	}
	my $comment;
	while (<OBJDUMPDATA>) {
	chomp();
	if (/^In archive/) {
	# Archives are always conglomerate
	$comment = "GCC:GCC:";
	last;
	}
	next if (! /^[ 0-9a-f]{5,} /);
	$comment .= substr($_, 43);
	}
	close(OBJDUMPDATA);
	if (!defined($comment) \|\| $comment !~ /GCC\:.*GCC\:/m) {
	printf STDERR "No source file found for $fullname\n";
	}
	return;
	}
	if (! open(NMDATA, "$nm $basename\|")) {
	printf STDERR "$nm $fullname failed $!\n";
	return;
	}
	my @nmdata;
	while (<NMDATA>) {
	chop;
	($type, $name) = (split(/ +/, $_, 3))[1..2];
	# Expected types
	# A absolute symbol
	# B weak external reference to data that has been resolved
	# C global variable, uninitialised
	# D global variable, initialised
	# G global variable, initialised, small data section
	# R global array, initialised
	# S global variable, uninitialised, small bss
	# T global label/procedure
	# U external reference
	# W weak external reference to text that has been resolved
	# a assembler equate
	# b static variable, uninitialised
	# d static variable, initialised
	# g static variable, initialised, small data section
	# r static array, initialised
	# s static variable, uninitialised, small bss
	# t static label/procedures
	# w weak external reference to text that has not been resolved
	# ? undefined type, used a lot by modules
	if ($type !~ /^[ABCDGRSTUWabdgrstw?]$/) {
	printf STDERR "nm output for $fullname contains unknown type '$_'\n";
	}
	elsif ($name =~ /\./) {
	# name with '.' is local static
	}
	else {
	$type = 'R' if ($type eq '?'); # binutils replaced ? with R at one point
	# binutils keeps changing the type for exported symbols, force it to R
	$type = 'R' if ($name =~ /^__ksymtab/ \|\| $name =~ /^__kstrtab/);
	$name =~ s/_R[a-f0-9]{8}$//; # module versions adds this
	if ($type =~ /[ABCDGRSTW]/ &&
	$name ne 'init_module' &&
	$name ne 'cleanup_module' &&
	$name ne 'Using_Versions' &&
	$name !~ /^Version_[0-9]+$/ &&
	$name !~ /^__parm_/ &&
	$name !~ /^__kstrtab/ &&
	$name !~ /^__ksymtab/ &&
	$name !~ /^__kcrctab_/ &&
	$name !~ /^__exitcall_/ &&
	$name !~ /^__initcall_/ &&
	$name !~ /^__kdb_initcall_/ &&
	$name !~ /^__kdb_exitcall_/ &&
	$name !~ /^__module_/ &&
	$name !~ /^__mod_/ &&
	$name !~ /^__crc_/ &&
	$name ne '__this_module' &&
	$name ne 'kernel_version') {
	if (!exists($def{$name})) {
	$def{$name} = [];
	}
	push(@{$def{$name}}, $fullname);
	}
	push(@nmdata, "$type $name");
	if ($name =~ /^__ksymtab_/) {
	$name = substr($name, 10);
	if (!exists($ksymtab{$name})) {
	$ksymtab{$name} = [];
	}
	push(@{$ksymtab{$name}}, $fullname);
	}
	}
	}
	close(NMDATA);
	if ($#nmdata < 0) {
	if (
	$fullname ne "lib/brlock.o"
	&& $fullname ne "lib/dec_and_lock.o"
	&& $fullname ne "fs/xfs/xfs_macros.o"
	&& $fullname ne "drivers/ide/ide-probe-mini.o"
	&& $fullname ne "usr/initramfs_data.o"
	&& $fullname ne "drivers/acpi/executer/exdump.o"
	&& $fullname ne "drivers/acpi/resources/rsdump.o"
	&& $fullname ne "drivers/acpi/namespace/nsdumpdv.o"
	&& $fullname ne "drivers/acpi/namespace/nsdump.o"
	&& $fullname ne "arch/ia64/sn/kernel/sn2/io.o"
	&& $fullname ne "arch/ia64/kernel/gate-data.o"
	&& $fullname ne "drivers/ieee1394/oui.o"
	&& $fullname ne "security/capability.o"
	&& $fullname ne "sound/core/wrappers.o"
	&& $fullname ne "fs/ntfs/sysctl.o"
	&& $fullname ne "fs/jfs/jfs_debug.o"
	) {
	printf "No nm data for $fullname\n";
	}
	return;
	}
	$nmdata{$fullname} = \@nmdata;
	}

	sub drop_def
	{
	my ($object, $name) = @_;
	my $nmdata = $nmdata{$object};
	my ($i, $j);
	for ($i = 0; $i <= $#{$nmdata}; ++$i) {
	if ($name eq (split(' ', $nmdata->[$i], 2))[1]) {
	splice(@{$nmdata{$object}}, $i, 1);
	my $def = $def{$name};
	for ($j = 0; $j < $#{$def{$name}}; ++$j) {
	if ($def{$name}[$j] eq $object) {
	splice(@{$def{$name}}, $j, 1);
	}
	}
	last;
	}
	}
	}

	sub list_multiply_defined
	{
	my ($name, $module);
	foreach $name (keys(%def)) {
	if ($#{$def{$name}} > 0) {
	# Special case for cond_syscall
	if ($#{$def{$name}} == 1 && $name =~ /^sys_/ &&
	($def{$name}[0] eq "kernel/sys.o" \|\|
	$def{$name}[1] eq "kernel/sys.o")) {
	&drop_def("kernel/sys.o", $name);
	next;
	}
	# Special case for i386 entry code
	if ($#{$def{$name}} == 1 && $name =~ /^__kernel_/ &&
	$def{$name}[0] eq "arch/i386/kernel/vsyscall-int80.o" &&
	$def{$name}[1] eq "arch/i386/kernel/vsyscall-sysenter.o") {
	&drop_def("arch/i386/kernel/vsyscall-sysenter.o", $name);
	next;
	}
	printf "$name is multiply defined in :-\n";
	foreach $module (@{$def{$name}}) {
	printf "\t$module\n";
	}
	}
	}
	}

	sub resolve_external_references
	{
	my ($object, $type, $name, $i, $j, $kstrtab, $ksymtab, $export);
	printf "\n";
	foreach $object (keys(%nmdata)) {
	my $nmdata = $nmdata{$object};
	for ($i = 0; $i <= $#{$nmdata}; ++$i) {
	($type, $name) = split(' ', $nmdata->[$i], 2);
	if ($type eq "U" \|\| $type eq "w") {
	if (exists($def{$name}) \|\| exists($ksymtab{$name})) {
	# add the owning object to the nmdata
	$nmdata->[$i] = "$type $name $object";
	# only count as a reference if it is not EXPORT_...
	$kstrtab = "R __kstrtab_$name";
	$ksymtab = "R __ksymtab_$name";
	$export = 0;
	for ($j = 0; $j <= $#{$nmdata}; ++$j) {
	if ($nmdata->[$j] eq $kstrtab \|\|
	$nmdata->[$j] eq $ksymtab) {
	$export = 1;
	last;
	}
	}
	if ($export) {
	$export{$name} = "";
	}
	else {
	$ref{$name} = ""
	}
	}
	elsif ( $name ne "mod_use_count_"
	&& $name ne "__initramfs_end"
	&& $name ne "__initramfs_start"
	&& $name ne "_einittext"
	&& $name ne "_sinittext"
	&& $name ne "kallsyms_names"
	&& $name ne "kallsyms_num_syms"
	&& $name ne "kallsyms_addresses"
	&& $name ne "__this_module"
	&& $name ne "_etext"
	&& $name ne "_edata"
	&& $name ne "_end"
	&& $name ne "__bss_start"
	&& $name ne "_text"
	&& $name ne "_stext"
	&& $name ne "__gp"
	&& $name ne "ia64_unw_start"
	&& $name ne "ia64_unw_end"
	&& $name ne "__init_begin"
	&& $name ne "__init_end"
	&& $name ne "__bss_stop"
	&& $name ne "__nosave_begin"
	&& $name ne "__nosave_end"
	&& $name ne "pg0"
	&& $name ne "__module_text_address"
	&& $name !~ /^__sched_text_/
	&& $name !~ /^__start_/
	&& $name !~ /^__end_/
	&& $name !~ /^__stop_/
	&& $name !~ /^__scheduling_functions_.*_here/
	&& $name !~ /^__.*initcall_/
	&& $name !~ /^__.*per_cpu_start/
	&& $name !~ /^__.*per_cpu_end/
	&& $name !~ /^__alt_instructions/
	&& $name !~ /^__setup_/
	&& $name !~ /^jiffies/
	&& $name !~ /^__mod_timer/
	&& $name !~ /^__mod_page_state/
	&& $name !~ /^init_module/
	&& $name !~ /^cleanup_module/
	) {
	printf "Cannot resolve ";
	printf "weak " if ($type eq "w");
	printf "reference to $name from $object\n";
	}
	}
	}
	}
	}

	sub list_extra_externals
	{
	my %noref = ();
	my ($name, @module, $module, $export);
	foreach $name (keys(%def)) {
	if (! exists($ref{$name})) {
	@module = @{$def{$name}};
	foreach $module (@module) {
	if (! exists($noref{$module})) {
	$noref{$module} = [];
	}
	push(@{$noref{$module}}, $name);
	}
	}
	}
	if (%noref) {
	printf "\nExternally defined symbols with no external references\n";
	foreach $module (sort(keys(%noref))) {
	printf " $module\n";
	foreach (sort(@{$noref{$module}})) {
	if (exists($export{$_})) {
	$export = " (export only)";
	}
	else {
	$export = "";
	}
	printf " $_$export\n";
	}
	}
	}
	}