Re: [Xen-devel] [PATCH OSSTEST 3/5] Cope with Jessie's d-i vg name

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

On Thu, 2015-05-21 at 17:04 +0100, Wei Liu wrote:
> On Thu, May 21, 2015 at 04:10:02PM +0100, Ian Campbell wrote:
> > On Wed, 2015-05-20 at 18:56 +0100, Wei Liu wrote:
> > > In ts-xen-build-prep, replace matching lenny with jessie since lenny is
> > > not used in production anymore.
> > 
> > AIUI the default VG name scheme changed? Can you say how here please.
> > 
> 
> Sure.
> 
> > Also I think in general we should aim for the "non-exceptional" case to
> > be the default one, and use explicit matching for issues with historical
> > versions. IOW test for wheezy and earlier and override the default (i.e.
> > Jessie) name. The rationale is that we shouldn't need to add Stretch
> > here too unless it also differs from Jessie.
> > 
> > That principal seems to apply to a some of the following patches too.
> > 
> > WRT "wheezy and earlier" I've been wondering about providing a function
> > to transform a Debian code name to a sortable integer. e.g.
> > 
> > sub debver($) {
> >     my %vers = qw(Lenny 50
> >                   Squeeze 60
> >                   Wheezy 70
> >                   Jessie 80
> >                   Stretch 90
> >                   Sid 1000000);
> >     # Unknown is > sid...
> >     return $vers{ucfirst($_[0])) // 1000001;
> > }
> > 
> > so you can do things like
> >     if ( debver($ho->{Suite}) < debver('jessie') ) {
> >         workaround_a_thing();
> > 
> 
> You would need to test for "$ho->{Suite} == A" or "A < $ho->{Suite} < B".

if ( debver($ho->{Suite}) <= debver('squeeze') )
    handle Squeeze or earlier
elseif ( debver($ho->{Suite}) <= debver('wheezy') )
    handle Wheezy
else
    handle Jessie onwards

I'm not sure if Perl supports
        debver('squeeze') < debver($ho->{Suite}) <= debver('wheezy')
like some languages do.

> And it's just another form of saying "if ($ho->{Suite} =~ /XXX/)" IMHO.

The difference is you don't need to enumerate all the names. e.g.
"lenny|squeeze|wheezy" becomes "< debver('wheezy')"

> > Thoughts?
> 
> That would be nice but I doubt it would be of much use -- who
> doesn't want the latest version in production... ;-)

People who think it is useful to continue to test Wheezy for some
reason? People who have other constraints preventing them from upgrading
right away? People who want to use a _newer_ version for some reason and
want to make Stretch work while not breaking Wheezy/Jessie for everyone
else.

If it were expensive to support I'd agree, but I don't think it is,
especially if you arrange to never need to touch it again...

BTW, at some point I'm hoping to extend my distros flight stuff to cover
testing the distro host packages, at which point it would naturally be
useful to cover at least current stable and current testing, if not
oldstable or sid.

Ian.


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