[Buildroot] [PATCHv2 1/1] board/wandboard: fix perl related linux compilation error

[Buildroot] [PATCHv2 1/1] board/wandboard: fix perl related linux compilation error

[imrehg at gmail.com]

From: Gergely Imreh <imrehg@gmail.com>

Replace the "timeconst" perl script with a bc script to fix an
error due to syntax changes in perl which resulted in linux
compilation error for the wandboard's 3.8 kernel. The patch is
backported, kernels from 3.9 onward already have this change.

Signed-off-by: Gergely Imreh <imrehg@gmail.com>
---
Changes v1 -> v2:

 - backport patch from kernel instead of mailing list (suggested by Yann E. MORIN)

---
 .../patches/linux/replace-timeconst-script.patch   | 554 +++++++++++++++++++++
 configs/wandboard_defconfig                        |   1 +
 2 files changed, 555 insertions(+)
 create mode 100644 board/wandboard/patches/linux/replace-timeconst-script.patch

diff --git a/board/wandboard/patches/linux/replace-timeconst-script.patch b/board/wandboard/patches/linux/replace-timeconst-script.patch
new file mode 100644
index 0000000..bbf3fe6
--- /dev/null
+++ b/board/wandboard/patches/linux/replace-timeconst-script.patch
@@ -0,0 +1,554 @@
+Backported 70730bca1331fc50c3caacaea00439de1325bd6e from linux
+to Wandboard's 3.8 kernel.
+
+Original commit message below.
+
+Signed-off-by: Gergely Imreh <imrehg@gmail.com>
+
+---
+
+bc is the standard tool for multi-precision arithmetic.  We switched
+to Perl because akpm reported a hard-to-reproduce build hang, which
+was very odd because affected and unaffected machines were all running
+the same version of GNU bc.
+
+Unfortunately switching to Perl required a really ugly "canning"
+mechanism to support Perl < 5.8 installations lacking the Math::BigInt
+module.
+
+It was recently pointed out to me that some very old versions of GNU
+make had problems with pipes in subshells, which was indeed the
+construct used in the Makefile rules in that version of the patch;
+Perl didn't need it so switching to Perl fixed the problem for
+unrelated reasons.  With the problem (hopefully) root-caused, we can
+switch back to bc and do the arbitrary-precision arithmetic naturally.
+
+Signed-off-by: H. Peter Anvin <hpa@zytor.com>
+Cc: Andrew Morton <akpm@linux-foundation.org>
+Acked-by: Sam Ravnborg <sam@ravnborg.org>
+Signed-off-by: Michal Marek <mmarek@suse.cz>
+
+--- a/kernel/Makefile
++++ b/kernel/Makefile
+@@ -133,8 +133,16 @@ $(obj)/config_data.h: $(obj)/config_data.gz FORCE
+ 
+ $(obj)/time.o: $(obj)/timeconst.h
+ 
+-quiet_cmd_timeconst  = TIMEC   $@
+-      cmd_timeconst  = $(PERL) $< $(CONFIG_HZ) > $@
++quiet_cmd_hzfile = HZFILE  $@
++      cmd_hzfile = echo "hz=$(CONFIG_HZ)" > $@
++
++targets += hz.bc
++$(obj)/hz.bc: $(objtree)/include/config/hz.h FORCE
++	$(call if_changed,hzfile)
++
++quiet_cmd_bc  = BC      $@
++      cmd_bc  = bc -q $(filter-out FORCE,$^) > $@
++
+ targets += timeconst.h
+-$(obj)/timeconst.h: $(src)/timeconst.pl FORCE
+-	$(call if_changed,timeconst)
++$(obj)/timeconst.h: $(obj)/hz.bc $(src)/timeconst.bc FORCE
++	$(call if_changed,bc)
+diff --git a/kernel/timeconst.bc b/kernel/timeconst.bc
+new file mode 100644
+index 0000000..511bdf2
+--- /dev/null
++++ b/kernel/timeconst.bc
+@@ -0,0 +1,108 @@
++scale=0
++
++define gcd(a,b) {
++	auto t;
++	while (b) {
++		t = b;
++		b = a % b;
++		a = t;
++	}
++	return a;
++}
++
++/* Division by reciprocal multiplication. */
++define fmul(b,n,d) {
++       return (2^b*n+d-1)/d;
++}
++
++/* Adjustment factor when a ceiling value is used.  Use as:
++   (imul * n) + (fmulxx * n + fadjxx) >> xx) */
++define fadj(b,n,d) {
++	auto v;
++	d = d/gcd(n,d);
++	v = 2^b*(d-1)/d;
++	return v;
++}
++
++/* Compute the appropriate mul/adj values as well as a shift count,
++   which brings the mul value into the range 2^b-1 <= x < 2^b.  Such
++   a shift value will be correct in the signed integer range and off
++   by@most one in the upper half of the unsigned range. */
++define fmuls(b,n,d) {
++	auto s, m;
++	for (s = 0; 1; s++) {
++		m = fmul(s,n,d);
++		if (m >= 2^(b-1))
++			return s;
++	}
++	return 0;
++}
++
++define timeconst(hz) {
++	print "/* Automatically generated by kernel/timeconst.bc */\n"
++	print "/* Time conversion constants for HZ == ", hz, " */\n"
++	print "\n"
++
++	print "#ifndef KERNEL_TIMECONST_H\n"
++	print "#define KERNEL_TIMECONST_H\n\n"
++
++	print "#include <linux/param.h>\n"
++	print "#include <linux/types.h>\n\n"
++
++	print "#if HZ != ", hz, "\n"
++	print "#error \qkernel/timeconst.h has the wrong HZ value!\q\n"
++	print "#endif\n\n"
++
++	if (hz < 2) {
++		print "#error Totally bogus HZ value!\n"
++	} else {
++		s=fmuls(32,1000,hz)
++		obase=16
++		print "#define HZ_TO_MSEC_MUL32\tU64_C(0x", fmul(s,1000,hz), ")\n"
++		print "#define HZ_TO_MSEC_ADJ32\tU64_C(0x", fadj(s,1000,hz), ")\n"
++		obase=10
++		print "#define HZ_TO_MSEC_SHR32\t", s, "\n"
++
++		s=fmuls(32,hz,1000)
++		obase=16
++		print "#define MSEC_TO_HZ_MUL32\tU64_C(0x", fmul(s,hz,1000), ")\n"
++		print "#define MSEC_TO_HZ_ADJ32\tU64_C(0x", fadj(s,hz,1000), ")\n"
++		obase=10
++		print "#define MSEC_TO_HZ_SHR32\t", s, "\n"
++
++		obase=10
++		cd=gcd(hz,1000)
++		print "#define HZ_TO_MSEC_NUM\t\t", 1000/cd, "\n"
++		print "#define HZ_TO_MSEC_DEN\t\t", hz/cd, "\n"
++		print "#define MSEC_TO_HZ_NUM\t\t", hz/cd, "\n"
++		print "#define MSEC_TO_HZ_DEN\t\t", 1000/cd, "\n"
++		print "\n"
++
++		s=fmuls(32,1000000,hz)
++		obase=16
++		print "#define HZ_TO_USEC_MUL32\tU64_C(0x", fmul(s,1000000,hz), ")\n"
++		print "#define HZ_TO_USEC_ADJ32\tU64_C(0x", fadj(s,1000000,hz), ")\n"
++		obase=10
++		print "#define HZ_TO_USEC_SHR32\t", s, "\n"
++
++		s=fmuls(32,hz,1000000)
++		obase=16
++		print "#define USEC_TO_HZ_MUL32\tU64_C(0x", fmul(s,hz,1000000), ")\n"
++		print "#define USEC_TO_HZ_ADJ32\tU64_C(0x", fadj(s,hz,1000000), ")\n"
++		obase=10
++		print "#define USEC_TO_HZ_SHR32\t", s, "\n"
++
++		obase=10
++		cd=gcd(hz,1000000)
++		print "#define HZ_TO_USEC_NUM\t\t", 1000000/cd, "\n"
++		print "#define HZ_TO_USEC_DEN\t\t", hz/cd, "\n"
++		print "#define USEC_TO_HZ_NUM\t\t", hz/cd, "\n"
++		print "#define USEC_TO_HZ_DEN\t\t", 1000000/cd, "\n"
++		print "\n"
++
++		print "#endif /* KERNEL_TIMECONST_H */\n"
++	}
++	halt
++}
++
++timeconst(hz)
+diff --git a/kernel/timeconst.pl b/kernel/timeconst.pl
+deleted file mode 100644
+index eb51d76..0000000
+--- a/kernel/timeconst.pl
++++ /dev/null
+@@ -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;
+-- 
+cgit v0.10.2
+
diff --git a/configs/wandboard_defconfig b/configs/wandboard_defconfig
index 5d74fc3..5ce5fdf 100644
--- a/configs/wandboard_defconfig
+++ b/configs/wandboard_defconfig
@@ -1,5 +1,6 @@
 BR2_arm=y
 BR2_cortex_a9=y
+BR2_GLOBAL_PATCH_DIR="board/wandboard/patches"
 BR2_KERNEL_HEADERS_VERSION=y
 BR2_DEFAULT_KERNEL_VERSION="3.0.101"
 BR2_PACKAGE_HOST_LINUX_HEADERS_CUSTOM_3_0=y
-- 
2.5.3

[Buildroot] [PATCHv2 1/1] board/wandboard: fix perl related linux compilation error

[Thomas Petazzoni]

Hello,

On Tue, 22 Sep 2015 10:45:21 +0800, imrehg at gmail.com wrote:
> From: Gergely Imreh <imrehg@gmail.com>
> 
> Replace the "timeconst" perl script with a bc script to fix an
> error due to syntax changes in perl which resulted in linux
> compilation error for the wandboard's 3.8 kernel. The patch is
> backported, kernels from 3.9 onward already have this change.
> 
> Signed-off-by: Gergely Imreh <imrehg@gmail.com>

The problem with this patch is that it fixes the problem specifically
for the wandboard_defconfig. Any other person building another kernel
version affected by the same problem will face the problem.

If the problem is serious, I don't really see another option than
having some logic in linux.mk to detect if the kernel is affected by
the problem, and replacing the perl script by a bc script.

Other ideas?

Best regards,

Thomas
-- 
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

[Buildroot] [PATCHv2 1/1] board/wandboard: fix perl related linux compilation error

[Gergely Imreh]

On 22 September 2015 at 21:47, Thomas Petazzoni
<thomas.petazzoni@free-electrons.com> wrote:
> Hello,
>
> On Tue, 22 Sep 2015 10:45:21 +0800, imrehg at gmail.com wrote:
>> From: Gergely Imreh <imrehg@gmail.com>
>>
>> Replace the "timeconst" perl script with a bc script to fix an
>> error due to syntax changes in perl which resulted in linux
>> compilation error for the wandboard's 3.8 kernel. The patch is
>> backported, kernels from 3.9 onward already have this change.
>>
>> Signed-off-by: Gergely Imreh <imrehg@gmail.com>
>
> The problem with this patch is that it fixes the problem specifically
> for the wandboard_defconfig. Any other person building another kernel
> version affected by the same problem will face the problem.
>
> If the problem is serious, I don't really see another option than
> having some logic in linux.mk to detect if the kernel is affected by
> the problem, and replacing the perl script by a bc script.
>
> Other ideas?

At cursory glance, this should affect every kernel before 3.9 (when it
was switched to bc script), please correct me if I'm wrong.

On the other hand, looking at this patch, it appears to need more
backporting than the original single line of perl fix, and likely not
very portable (because of touching the Makefile). The other one one is
simple and very well defined. I'd probably start from that patch if
large variety of unknown kernel versions need to be potentially fixed.

But this is just a thought.

Cheers,
  Gergely

>
> Best regards,
>
> Thomas
> --
> Thomas Petazzoni, CTO, Free Electrons
> Embedded Linux, Kernel and Android engineering
> http://free-electrons.com

[Buildroot] [PATCHv2 1/1] board/wandboard: fix perl related linux compilation error

[Peter Korsgaard]

>>>>> "Thomas" == Thomas Petazzoni <thomas.petazzoni@free-electrons.com> writes:

 > Hello,
 > On Tue, 22 Sep 2015 10:45:21 +0800, imrehg at gmail.com wrote:
 >> From: Gergely Imreh <imrehg@gmail.com>
 >> 
 >> Replace the "timeconst" perl script with a bc script to fix an
 >> error due to syntax changes in perl which resulted in linux
 >> compilation error for the wandboard's 3.8 kernel. The patch is
 >> backported, kernels from 3.9 onward already have this change.
 >> 
 >> Signed-off-by: Gergely Imreh <imrehg@gmail.com>

 > The problem with this patch is that it fixes the problem specifically
 > for the wandboard_defconfig. Any other person building another kernel
 > version affected by the same problem will face the problem.

Presumably only if they have a new enough perl version and/or old enough
make version? (the last shouldn't be an issue as we require make 3.81).

I haven't seen the problem myself (or heard other reports about it), so
it presumably only triggers for a few people.

 > If the problem is serious, I don't really see another option than
 > having some logic in linux.mk to detect if the kernel is affected by
 > the problem, and replacing the perl script by a bc script.

Step 1 must be to understand what the issue is exactly and what version
of perl/make triggers it.

Imreh, can you clarify?

-- 
Bye, Peter Korsgaard

[Buildroot] [PATCHv2 1/1] board/wandboard: fix perl related linux compilation error

[Peter Korsgaard]

>>>>> "Peter" == Peter Korsgaard <peter@korsgaard.com> writes:

Hi,

 >> If the problem is serious, I don't really see another option than
 >> having some logic in linux.mk to detect if the kernel is affected by
 >> the problem, and replacing the perl script by a bc script.

 > Step 1 must be to understand what the issue is exactly and what version
 > of perl/make triggers it.

 > Imreh, can you clarify?

Could it be that your system perl enables strict mode by default? What
distribution and perl version are you using?

I just built wandboard_defconfig without any problems here (perl 5.20.2
/ Debian).

-- 
Bye, Peter Korsgaard

[Buildroot] [PATCHv2 1/1] board/wandboard: fix perl related linux compilation error

[Arnout Vandecappelle]

On 03-10-15 21:48, Peter Korsgaard wrote:
>>>>>> "Peter" == Peter Korsgaard <peter@korsgaard.com> writes:
> 
> Hi,
> 
>  >> If the problem is serious, I don't really see another option than
>  >> having some logic in linux.mk to detect if the kernel is affected by
>  >> the problem, and replacing the perl script by a bc script.
> 
>  > Step 1 must be to understand what the issue is exactly and what version
>  > of perl/make triggers it.
> 
>  > Imreh, can you clarify?
> 
> Could it be that your system perl enables strict mode by default? What
> distribution and perl version are you using?
> 
> I just built wandboard_defconfig without any problems here (perl 5.20.2
> / Debian).
> 

 It's with perl 5.22. Should at least be mentioned in the commit log.

 This also means that whenever host-perl is built before the kernel, you'll bump
into this issue (because host-perl is in the PATH passed to the kernel build).

 But so indeed, this is going to be an issue for all kernels, so I'm with Imreh
that the solution is to have a simple sed-patch that can be applied to all kernels.

 Regards,
 Arnout

-- 
Arnout Vandecappelle                          arnout at mind be
Senior Embedded Software Architect            +32-16-286500
Essensium/Mind                                http://www.mind.be
G.Geenslaan 9, 3001 Leuven, Belgium           BE 872 984 063 RPR Leuven
LinkedIn profile: http://www.linkedin.com/in/arnoutvandecappelle
GPG fingerprint:  7493 020B C7E3 8618 8DEC 222C 82EB F404 F9AC 0DDF

[Buildroot] [PATCHv2 1/1] board/wandboard: fix perl related linux compilation error

[Peter Korsgaard]

>>>>> "Arnout" == Arnout Vandecappelle <arnout@mind.be> writes:

Hi,

 >  It's with perl 5.22. Should at least be mentioned in the commit log.

 >  This also means that whenever host-perl is built before the kernel, you'll bump
 > into this issue (because host-perl is in the PATH passed to the kernel build).

 >  But so indeed, this is going to be an issue for all kernels, so I'm with Imreh
 > that the solution is to have a simple sed-patch that can be applied to all kernels.

Agreed. From the 5.22 changelog:

defined(@array) and defined(%hash) are now fatal errors

These have been deprecated since v5.6.1 and have raised deprecation
warnings since v5.16.

https://metacpan.org/pod/distribution/perl/pod/perldelta.pod#defined-array-and-defined-hash-are-now-fatal-errors

-- 
Venlig hilsen,
Peter Korsgaard 

[Buildroot] [PATCHv2 1/1] board/wandboard: fix perl related linux compilation error

[Thomas Petazzoni]

Hello,

On Tue, 22 Sep 2015 10:45:21 +0800, imrehg at gmail.com wrote:
> From: Gergely Imreh <imrehg@gmail.com>
> 
> Replace the "timeconst" perl script with a bc script to fix an
> error due to syntax changes in perl which resulted in linux
> compilation error for the wandboard's 3.8 kernel. The patch is
> backported, kernels from 3.9 onward already have this change.
> 
> Signed-off-by: Gergely Imreh <imrehg@gmail.com>

We finally fixed this problem in a different way, that is generic to
all boards/kernel versions.

See the commit at
https://git.busybox.net/buildroot/commit/linux?id=d6a5d71aba8e21b8aa28d93075a603297d1d3b3c.

Consequently, I've marked your patch as "Rejected" in our patch
tracking system. Thanks for having reported the issue in the first
place!

Thomas
-- 
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com