What is the oldest perl version being used with the kernel ? update oldest supported to 5.14 ?

What is the oldest perl version being used with the kernel ? update oldest supported to 5.14 ?

[Joe Perches]

Perl 5.8 is nearly 20 years old now.

https://en.wikipedia.org/wiki/Perl_5_version_history

checkpatch uses regexes that are incompatible with perl versions
earlier than 5.10, but these uses are currently runtime checked
and skipped if the perl version is too old.  This runtime checking
skips several useful tests.

There is also some desire for tools like kernel-doc, checkpatch and
get_maintainer to use a common library of regexes and functions:
https://lore.kernel.org/lkml/YR2lexDd9N0sWxIW@casper.infradead.org/

It'd be useful to set the minimum perl version to something more modern.

I believe perl 5.14, now only a decade old, is a reasonable target.

Any objections or suggestions for a newer minimum version?

Re: What is the oldest perl version being used with the kernel ? update oldest supported to 5.14 ?

[Willy Tarreau]

On Fri, Aug 20, 2021 at 10:27:59AM -0700, Joe Perches wrote:
> Perl 5.8 is nearly 20 years old now.
> 
> https://en.wikipedia.org/wiki/Perl_5_version_history
> 
> checkpatch uses regexes that are incompatible with perl versions
> earlier than 5.10, but these uses are currently runtime checked
> and skipped if the perl version is too old.  This runtime checking
> skips several useful tests.
> 
> There is also some desire for tools like kernel-doc, checkpatch and
> get_maintainer to use a common library of regexes and functions:
> https://lore.kernel.org/lkml/YR2lexDd9N0sWxIW@casper.infradead.org/
> 
> It'd be useful to set the minimum perl version to something more modern.
> 
> I believe perl 5.14, now only a decade old, is a reasonable target.
> 
> Any objections or suggestions for a newer minimum version?

It's probably reasonable, even the Slackware 14.2 on my home PC, which
is starting to date, ships a 5.22.

Willy

Re: What is the oldest perl version being used with the kernel ? update oldest supported to 5.14 ?

[Matthew Wilcox]

On Fri, Aug 20, 2021 at 10:27:59AM -0700, Joe Perches wrote:
> Perl 5.8 is nearly 20 years old now.
> 
> https://en.wikipedia.org/wiki/Perl_5_version_history
> 
> checkpatch uses regexes that are incompatible with perl versions
> earlier than 5.10, but these uses are currently runtime checked
> and skipped if the perl version is too old.  This runtime checking
> skips several useful tests.
> 
> There is also some desire for tools like kernel-doc, checkpatch and
> get_maintainer to use a common library of regexes and functions:
> https://lore.kernel.org/lkml/YR2lexDd9N0sWxIW@casper.infradead.org/
> 
> It'd be useful to set the minimum perl version to something more modern.
> 
> I believe perl 5.14, now only a decade old, is a reasonable target.
> 
> Any objections or suggestions for a newer minimum version?

Not an objection per se, but some data points.

Oracle Linux 5 (released 2007, still under support) has perl 5.8.8
Oracle Linux 6 (released 2011) has perl 5.10.1
Oracle Linux 7 (released 2014) has perl 5.16.3
Oracle Linux 8 (released 2019) has perl 5.26.3

I don't know that we need to be able to build on a distro from 2007
or even from 2011.  I think it's reasonable to require updating to a
2014 distro in order to build a 2021 kernel.

For comparison, we currently require gcc-4.9 to build the kernel, and
4.9.0 was released in 2014.  So perl-5.16 wouldn't be an unreasonable
requirement, I believe.

Re: What is the oldest perl version being used with the kernel ? update oldest supported to 5.14 ?

[Kees Cook]

On Fri, Aug 20, 2021 at 07:25:50PM +0100, Matthew Wilcox wrote:
> On Fri, Aug 20, 2021 at 10:27:59AM -0700, Joe Perches wrote:
> > Perl 5.8 is nearly 20 years old now.
> > 
> > https://en.wikipedia.org/wiki/Perl_5_version_history
> > 
> > checkpatch uses regexes that are incompatible with perl versions
> > earlier than 5.10, but these uses are currently runtime checked
> > and skipped if the perl version is too old.  This runtime checking
> > skips several useful tests.
> > 
> > There is also some desire for tools like kernel-doc, checkpatch and
> > get_maintainer to use a common library of regexes and functions:
> > https://lore.kernel.org/lkml/YR2lexDd9N0sWxIW@casper.infradead.org/
> > 
> > It'd be useful to set the minimum perl version to something more modern.
> > 
> > I believe perl 5.14, now only a decade old, is a reasonable target.
> > 
> > Any objections or suggestions for a newer minimum version?
> 
> Not an objection per se, but some data points.
> 
> Oracle Linux 5 (released 2007, still under support) has perl 5.8.8
> Oracle Linux 6 (released 2011) has perl 5.10.1
> Oracle Linux 7 (released 2014) has perl 5.16.3
> Oracle Linux 8 (released 2019) has perl 5.26.3
> 
> I don't know that we need to be able to build on a distro from 2007
> or even from 2011.  I think it's reasonable to require updating to a
> 2014 distro in order to build a 2021 kernel.
> 
> For comparison, we currently require gcc-4.9 to build the kernel, and
> 4.9.0 was released in 2014.  So perl-5.16 wouldn't be an unreasonable
> requirement, I believe.

Ubuntu name/version mapping: https://wiki.ubuntu.com/
Ubuntu Perl versions: https://launchpad.net/ubuntu/+source/perl

The oldest publicly supported Ubuntu (18.04 Bionic) uses Perl 5.26.

-- 
Kees Cook