Date: Wed, 18 Apr 2018 16:41:39 +0200
From: Cornelia Huck <cohuck@redhat.com>
Message-ID: <20180418164139.0206004d.cohuck@redhat.com>
In-Reply-To: <20180418125545.GN27579@redhat.com>
References: <20180418123838.3511-1-olaf@aepfle.de>
	<20180418144538.4aa2f492.cohuck@redhat.com>
	<20180418125545.GN27579@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH v1] configure: require glib-2.24
To: "Daniel P. =?UTF-8?B?QmVycmFuZ8Op?=" <berrange@redhat.com>
Cc: Olaf Hering <olaf@aepfle.de>, Peter Maydell <peter.maydell@linaro.org>, Fam Zheng <famz@redhat.com>, qemu-trivial@nongnu.org, Philippe =?UTF-8?B?TWF0aGlldS1EYXVkw6k=?= <f4bug@amsat.org>, "open list:All patches
	CC here" <qemu-devel@nongnu.org>, Gerd Hoffmann <kraxel@redhat.com>, Paolo Bonzini <pbonzini@redhat.com>

On Wed, 18 Apr 2018 13:55:45 +0100
Daniel P. Berrang=C3=A9 <berrange@redhat.com> wrote:

> On Wed, Apr 18, 2018 at 02:45:38PM +0200, Cornelia Huck wrote:
> > On Wed, 18 Apr 2018 14:38:37 +0200
> > Olaf Hering <olaf@aepfle.de> wrote:
> >  =20
> > > Since usage of g_realloc_n was introduced, glib-2.22 can not be used =
anymore.
> > > Fixes commit 418026ca43 ("util: Introduce vfio helpers")
> > >=20
> > > Signed-off-by: Olaf Hering <olaf@aepfle.de>
> > > ---
> > >  configure | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > >=20
> > > diff --git a/configure b/configure
> > > index 6e9b994f21..81760ef45a 100755
> > > --- a/configure
> > > +++ b/configure
> > > @@ -3369,7 +3369,7 @@ fi
> > >  if test "$mingw32" =3D yes; then
> > >      glib_req_ver=3D2.30
> > >  else
> > > -    glib_req_ver=3D2.22
> > > +    glib_req_ver=3D2.24
> > >  fi
> > >  glib_modules=3Dgthread-2.0
> > >  if test "$modules" =3D yes; then
> > >  =20
> >=20
> > Are we ready to give up support for whatever distro is still on 2.22?
> > (If yes, can we bump to an even newer glib version?) Or should we
> > rather solve this by adding a g_realloc_n implementation for that case?=
 =20
>=20
> Version 2.22 was released in Sep 2009, so coming up for 9 years old now.
>=20
> At some point we should to declare that platforms shipping >=3D NNN year
> old versions of software are not a desirable target for QEMU. What is
> our desired NNN value - 9 years feels awfully long to me.

The curse of the enterprise distro, I suppose... (And they might have
backported certain features without bumping the version number - I've
run into that problem in the past.)

>=20
> For libvirt we recently decided to become more aggressive[1] in culling o=
ld
> distros as supportable targets, declaring we'll only support non-EOL
> distros (for short life distros), or for long life distros (RHEL, LTS, et=
c)
> the most recent version, and the recent minus-1 for 2 years overlap.

That does not seem unreasonable. What about things like the MacOS stuff
(like fink vs. homebrew, as Peter mentioned?) Other platforms?

>=20
> Should we formalize similar guidelines for QEMU to give developers a
> guide for when it is reasonable to increase the min required version of
> any 3rd party library ?  glib is a mandatory dep, but we've countless
> other optional libraries we might wish to increase min versions for too,
> and no guide on when it is reasonable todo so.

If we decide on anything, we should definitely put it in writing :)
We've had this discussion way too often in the past...