[PATCH 1/3] Replace use of perl in 2.6.30 build

From: Rob Landley
Date: Mon Jun 22 2009 - 18:41:38 EST

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From: Rob Landley <rob@xxxxxxxxxxx>

Replace kernel/timeconst.pl with kernel/timeconst.sh. The new shell script
is much simpler, about 1/4 the size, and runs on Red Hat 9 from 2003.

It requires a shell which can do 64 bit math, such as bash, busybox ash,
or dash.

Signed-off-by: Rob Landley <rob@xxxxxxxxxxx>
---

Changes from previous version (http://lkml.org/lkml/2009/1/3/218):

Cosmetic tweak to millisecond/microsecond loop to pipe a here document into
"while read". (Previous version had a for loop parsing arguments with spaces
via "cut", which prompted much bikeshedding.)

kernel/Makefile | 4
kernel/timeconst.pl | 378 ------------------------------------------
kernel/timeconst.sh | 148 ++++++++++++++++
3 files changed, 150 insertions(+), 380 deletions(-)

diff -ruN linux-2.6.30/kernel/Makefile linux-2.6.30.new/kernel/Makefile
--- linux-2.6.30/kernel/Makefile 2009-06-09 22:05:27.000000000 -0500
+++ linux-2.6.30.new/kernel/Makefile 2009-06-22 14:29:16.000000000 -0500
@@ -122,7 +122,7 @@
$(obj)/time.o: $(obj)/timeconst.h

quiet_cmd_timeconst = TIMEC $@
- cmd_timeconst = $(PERL) $< $(CONFIG_HZ) > $@
+ cmd_timeconst = $(CONFIG_SHELL) $< $(CONFIG_HZ) $@
targets += timeconst.h
-$(obj)/timeconst.h: $(src)/timeconst.pl FORCE
+$(obj)/timeconst.h: $(src)/timeconst.sh FORCE
$(call if_changed,timeconst)
diff -ruN linux-2.6.30/kernel/timeconst.pl linux-2.6.30.new/kernel/timeconst.pl
--- linux-2.6.30/kernel/timeconst.pl 2009-06-09 22:05:27.000000000 -0500
+++ linux-2.6.30.new/kernel/timeconst.pl 1969-12-31 18:00:00.000000000 -0600
@@ -1,378 +0,0 @@
-#!/usr/bin/perl
-# -----------------------------------------------------------------------
-#
-# Copyright 2007-2008 rPath, Inc. - All Rights Reserved
-#
-# This file is part of the Linux kernel, and is made available under
-# the terms of the GNU General Public License version 2 or (at your
-# option) any later version; incorporated herein by reference.
-#
-# -----------------------------------------------------------------------
-#
-
-#
-# Usage: timeconst.pl HZ > timeconst.h
-#
-
-# Precomputed values for systems without Math::BigInt
-# Generated by:
-# timeconst.pl --can 24 32 48 64 100 122 128 200 250 256 300 512 1000 1024 1200
-%canned_values = (
- 24 => [
- '0xa6aaaaab','0x2aaaaaa',26,
- 125,3,
- '0xc49ba5e4','0x1fbe76c8b4',37,
- 3,125,
- '0xa2c2aaab','0xaaaa',16,
- 125000,3,
- '0xc9539b89','0x7fffbce4217d',47,
- 3,125000,
- ], 32 => [
- '0xfa000000','0x6000000',27,
- 125,4,
- '0x83126e98','0xfdf3b645a',36,
- 4,125,
- '0xf4240000','0x0',17,
- 31250,1,
- '0x8637bd06','0x3fff79c842fa',46,
- 1,31250,
- ], 48 => [
- '0xa6aaaaab','0x6aaaaaa',27,
- 125,6,
- '0xc49ba5e4','0xfdf3b645a',36,
- 6,125,
- '0xa2c2aaab','0x15555',17,
- 62500,3,
- '0xc9539b89','0x3fffbce4217d',46,
- 3,62500,
- ], 64 => [
- '0xfa000000','0xe000000',28,
- 125,8,
- '0x83126e98','0x7ef9db22d',35,
- 8,125,
- '0xf4240000','0x0',18,
- 15625,1,
- '0x8637bd06','0x1fff79c842fa',45,
- 1,15625,
- ], 100 => [
- '0xa0000000','0x0',28,
- 10,1,
- '0xcccccccd','0x733333333',35,
- 1,10,
- '0x9c400000','0x0',18,
- 10000,1,
- '0xd1b71759','0x1fff2e48e8a7',45,
- 1,10000,
- ], 122 => [
- '0x8325c53f','0xfbcda3a',28,
- 500,61,
- '0xf9db22d1','0x7fbe76c8b',35,
- 61,500,
- '0x8012e2a0','0x3ef36',18,
- 500000,61,
- '0xffda4053','0x1ffffbce4217',45,
- 61,500000,
- ], 128 => [
- '0xfa000000','0x1e000000',29,
- 125,16,
- '0x83126e98','0x3f7ced916',34,
- 16,125,
- '0xf4240000','0x40000',19,
- 15625,2,
- '0x8637bd06','0xfffbce4217d',44,
- 2,15625,
- ], 200 => [
- '0xa0000000','0x0',29,
- 5,1,
- '0xcccccccd','0x333333333',34,
- 1,5,
- '0x9c400000','0x0',19,
- 5000,1,
- '0xd1b71759','0xfff2e48e8a7',44,
- 1,5000,
- ], 250 => [
- '0x80000000','0x0',29,
- 4,1,
- '0x80000000','0x180000000',33,
- 1,4,
- '0xfa000000','0x0',20,
- 4000,1,
- '0x83126e98','0x7ff7ced9168',43,
- 1,4000,
- ], 256 => [
- '0xfa000000','0x3e000000',30,
- 125,32,
- '0x83126e98','0x1fbe76c8b',33,
- 32,125,
- '0xf4240000','0xc0000',20,
- 15625,4,
- '0x8637bd06','0x7ffde7210be',43,
- 4,15625,
- ], 300 => [
- '0xd5555556','0x2aaaaaaa',30,
- 10,3,
- '0x9999999a','0x1cccccccc',33,
- 3,10,
- '0xd0555556','0xaaaaa',20,
- 10000,3,
- '0x9d495183','0x7ffcb923a29',43,
- 3,10000,
- ], 512 => [
- '0xfa000000','0x7e000000',31,
- 125,64,
- '0x83126e98','0xfdf3b645',32,
- 64,125,
- '0xf4240000','0x1c0000',21,
- 15625,8,
- '0x8637bd06','0x3ffef39085f',42,
- 8,15625,
- ], 1000 => [
- '0x80000000','0x0',31,
- 1,1,
- '0x80000000','0x0',31,
- 1,1,
- '0xfa000000','0x0',22,
- 1000,1,
- '0x83126e98','0x1ff7ced9168',41,
- 1,1000,
- ], 1024 => [
- '0xfa000000','0xfe000000',32,
- 125,128,
- '0x83126e98','0x7ef9db22',31,
- 128,125,
- '0xf4240000','0x3c0000',22,
- 15625,16,
- '0x8637bd06','0x1fff79c842f',41,
- 16,15625,
- ], 1200 => [
- '0xd5555556','0xd5555555',32,
- 5,6,
- '0x9999999a','0x66666666',31,
- 6,5,
- '0xd0555556','0x2aaaaa',22,
- 2500,3,
- '0x9d495183','0x1ffcb923a29',41,
- 3,2500,
- ]
-);
-
-$has_bigint = eval 'use Math::BigInt qw(bgcd); 1;';
-
-sub bint($)
-{
- my($x) = @_;
- return Math::BigInt->new($x);
-}
-
-#
-# Constants for division by reciprocal multiplication.
-# (bits, numerator, denominator)
-#
-sub fmul($$$)
-{
- my ($b,$n,$d) = @_;
-
- $n = bint($n);
- $d = bint($d);
-
- return scalar (($n << $b)+$d-bint(1))/$d;
-}
-
-sub fadj($$$)
-{
- my($b,$n,$d) = @_;
-
- $n = bint($n);
- $d = bint($d);
-
- $d = $d/bgcd($n, $d);
- return scalar (($d-bint(1)) << $b)/$d;
-}
-
-sub fmuls($$$) {
- my($b,$n,$d) = @_;
- my($s,$m);
- my($thres) = bint(1) << ($b-1);
-
- $n = bint($n);
- $d = bint($d);
-
- for ($s = 0; 1; $s++) {
- $m = fmul($s,$n,$d);
- return $s if ($m >= $thres);
- }
- return 0;
-}
-
-# Generate a hex value if the result fits in 64 bits;
-# otherwise skip.
-sub bignum_hex($) {
- my($x) = @_;
- my $s = $x->as_hex();
-
- return (length($s) > 18) ? undef : $s;
-}
-
-# Provides mul, adj, and shr factors for a specific
-# (bit, time, hz) combination
-sub muladj($$$) {
- my($b, $t, $hz) = @_;
- my $s = fmuls($b, $t, $hz);
- my $m = fmul($s, $t, $hz);
- my $a = fadj($s, $t, $hz);
- return (bignum_hex($m), bignum_hex($a), $s);
-}
-
-# Provides numerator, denominator values
-sub numden($$) {
- my($n, $d) = @_;
- my $g = bgcd($n, $d);
- return ($n/$g, $d/$g);
-}
-
-# All values for a specific (time, hz) combo
-sub conversions($$) {
- my ($t, $hz) = @_;
- my @val = ();
-
- # HZ_TO_xx
- push(@val, muladj(32, $t, $hz));
- push(@val, numden($t, $hz));
-
- # xx_TO_HZ
- push(@val, muladj(32, $hz, $t));
- push(@val, numden($hz, $t));
-
- return @val;
-}
-
-sub compute_values($) {
- my($hz) = @_;
- my @val = ();
- my $s, $m, $a, $g;
-
- if (!$has_bigint) {
- die "$0: HZ == $hz not canned and ".
- "Math::BigInt not available\n";
- }
-
- # MSEC conversions
- push(@val, conversions(1000, $hz));
-
- # USEC conversions
- push(@val, conversions(1000000, $hz));
-
- return @val;
-}
-
-sub outputval($$)
-{
- my($name, $val) = @_;
- my $csuf;
-
- if (defined($val)) {
- if ($name !~ /SHR/) {
- $val = "U64_C($val)";
- }
- printf "#define %-23s %s\n", $name.$csuf, $val.$csuf;
- }
-}
-
-sub output($@)
-{
- my($hz, @val) = @_;
- my $pfx, $bit, $suf, $s, $m, $a;
-
- print "/* Automatically generated by kernel/timeconst.pl */\n";
- print "/* Conversion constants for HZ == $hz */\n";
- print "\n";
- print "#ifndef KERNEL_TIMECONST_H\n";
- print "#define KERNEL_TIMECONST_H\n";
- print "\n";
-
- print "#include <linux/param.h>\n";
- print "#include <linux/types.h>\n";
-
- print "\n";
- print "#if HZ != $hz\n";
- print "#error \"kernel/timeconst.h has the wrong HZ value!\"\n";
- print "#endif\n";
- print "\n";
-
- foreach $pfx ('HZ_TO_MSEC','MSEC_TO_HZ',
- 'HZ_TO_USEC','USEC_TO_HZ') {
- foreach $bit (32) {
- foreach $suf ('MUL', 'ADJ', 'SHR') {
- outputval("${pfx}_$suf$bit", shift(@val));
- }
- }
- foreach $suf ('NUM', 'DEN') {
- outputval("${pfx}_$suf", shift(@val));
- }
- }
-
- print "\n";
- print "#endif /* KERNEL_TIMECONST_H */\n";
-}
-
-# Pretty-print Perl values
-sub perlvals(@) {
- my $v;
- my @l = ();
-
- foreach $v (@_) {
- if (!defined($v)) {
- push(@l, 'undef');
- } elsif ($v =~ /^0x/) {
- push(@l, "\'".$v."\'");
- } else {
- push(@l, $v.'');
- }
- }
- return join(',', @l);
-}
-
-($hz) = @ARGV;
-
-# Use this to generate the %canned_values structure
-if ($hz eq '--can') {
- shift(@ARGV);
- @hzlist = sort {$a <=> $b} (@ARGV);
-
- print "# Precomputed values for systems without Math::BigInt\n";
- print "# Generated by:\n";
- print "# timeconst.pl --can ", join(' ', @hzlist), "\n";
- print "\%canned_values = (\n";
- my $pf = "\t";
- foreach $hz (@hzlist) {
- my @values = compute_values($hz);
- print "$pf$hz => [\n";
- while (scalar(@values)) {
- my $bit;
- foreach $bit (32) {
- my $m = shift(@values);
- my $a = shift(@values);
- my $s = shift(@values);
- print "\t\t", perlvals($m,$a,$s), ",\n";
- }
- my $n = shift(@values);
- my $d = shift(@values);
- print "\t\t", perlvals($n,$d), ",\n";
- }
- print "\t]";
- $pf = ', ';
- }
- print "\n);\n";
-} else {
- $hz += 0; # Force to number
- if ($hz < 1) {
- die "Usage: $0 HZ\n";
- }
-
- @val = @{$canned_values{$hz}};
- if (!defined(@val)) {
- @val = compute_values($hz);
- }
- output($hz, @val);
-}
-exit 0;
diff -ruN linux-2.6.30/kernel/timeconst.sh linux-2.6.30.new/kernel/timeconst.sh
--- linux-2.6.30/kernel/timeconst.sh 1969-12-31 18:00:00.000000000 -0600
+++ linux-2.6.30.new/kernel/timeconst.sh 2009-06-22 14:29:16.000000000 -0500
@@ -0,0 +1,148 @@
+#!/bin/sh
+
+if [ $# -ne 2 ]
+then
+ echo "Usage: timeconst.sh HZ FILENAME"
+ echo
+ echo "Generate a header file with constants for coverting between"
+ echo "decimal HZ timer ticks and milisecond or microsecond delays."
+ echo
+ exit 1
+fi
+
+HZ=$1
+shift
+FILENAME=$1
+
+# Sanity test: even the shell in Red Hat 9 (circa 2003) supported 64 bit math.
+
+if [ $((1 << 32)) -lt 0 ]
+then
+ echo "timeconst.sh needs a shell with 64 bit math, such as bash,"
+ echo "busybox ash, or dash running on a 64 bit host."
+ exit 1
+fi
+
+# If this script exits for any reason before this trap is removed,
+# delete the output file so a partial file won't confuse the build.
+
+trap "rm $FILENAME" EXIT
+
+# Output start of header file
+
+cat > $FILENAME << EOF || exit 1
+/* Automatically generated by kernel/timeconst.sh */
+/* Conversion constants for HZ == $HZ */
+
+#ifndef __KERNEL_TIMECONST_H
+#define __KERNEL_TIMECONST_H
+
+#include <linux/param.h>
+#include <linux/types.h>
+
+#if HZ != $HZ
+#error "kernel/timeconst.h has the wrong HZ value!"
+#endif
+
+EOF
+
+# For both Milliseconds and Microseconds
+
+cat << EOF |
+MSEC 1000
+USEC 1000000
+EOF
+while read NAME PERIOD
+do
+ # Find greatest common denominator (using Euclid's algorithm)
+
+ A=$HZ
+ B=$PERIOD
+
+ while [ $B -ne 0 ]
+ do
+ C=$(( $A % $B ))
+ A=$B
+ B=$C
+ done
+
+ GCD=$A
+
+ # Do this for each direction (HZ_TO_PERIOD and PERIOD_TO_HZ)
+
+ for DIRECTION in 0 1
+ do
+ if [ $DIRECTION -eq 0 ]
+ then
+ CONVERT="HZ_TO_${NAME}"
+ FROM=$HZ
+ TO=$PERIOD
+ else
+ CONVERT="${NAME}_TO_HZ"
+ FROM=$PERIOD
+ TO=$HZ
+ fi
+
+ # Calculate 32 significant bits of MUL32 data.
+
+ SHIFT=0
+ while true
+ do
+ # This can't overflow 64 bit math. Pathological case
+ # (TO=1, FROM=1000000) uses around 32+20=52 bits.
+
+ MUL32=$(( ( ( $TO << $SHIFT ) + $FROM - 1 ) / $FROM ))
+
+ # Keep increasing $SHIFT until we've got 32 bits.
+
+ [ $MUL32 -gt $(( 1 << 31 )) ] && break
+ SHIFT=$(( $SHIFT + 1 ))
+ done
+ MUL32=$( printf %x $MUL32 )
+
+ # ADJ32 is just (((FROM/GCD)-1)<<SHIFT)/(FROM/GCD) but this
+ # can overflow 64 bit math (examples, HZ=24 or HZ=122).
+ # Pathological case could use 32+20+20=72 bits. (And this is
+ # the pathological case because a larger $HZ results in a
+ # smaller $SHIFT, so even insane HZ>USEC cases should be ok.)
+
+ # To get around this, we chop the bottom 32 bits off the
+ # calculation and then reassemble it to avoid overflow:
+ # 32+64=96, which is > 72.
+
+ ADJ32=$(( $FROM / $GCD ))
+ if [ $SHIFT -gt 32 ]
+ then
+ UPPER=$(( ( $ADJ32 - 1 ) << ( $SHIFT - 32 ) ))
+ LOWER=$(( ( $UPPER % $ADJ32 ) << 32 ))
+ ADJ32=$(( ( ( $UPPER / $ADJ32 ) << 32 ) + ( $LOWER / $ADJ32 )))
+ else
+ ADJ32=$(( ( ( $ADJ32 - 1 ) << $SHIFT) / $ADJ32 ))
+ fi
+ ADJ32=$( printf %x $ADJ32 )
+
+ NUM=$(( $TO / $GCD ))
+ DEN=$(( $FROM / $GCD ))
+
+ # Output next chunk of header data to file
+
+ (
+ echo "#define ${CONVERT}_MUL32 U64_C(0x$MUL32)" &&
+ echo "#define ${CONVERT}_ADJ32 U64_C(0x$ADJ32)" &&
+ echo "#define ${CONVERT}_SHR32 $SHIFT" &&
+ echo "#define ${CONVERT}_NUM U64_C($NUM)" &&
+ echo "#define ${CONVERT}_DEN U64_C($DEN)"
+ ) >> $FILENAME || exit 1
+ done
+done
+
+(
+ echo
+ echo "#endif /* __KERNEL_TIMECHONST_H */"
+) >> $FILENAME || exit 1
+
+# Don't rm $FILENAME on exit anymore.
+
+trap "" EXIT
+
+exit 0
--
Latency is more important than throughput. It's that simple. - Linus Torvalds
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Next message: Rob Landley: "Re: [PATCH 2/3] Remove perl from headers_install"
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