Re: [Qemu-devel] [PATCH 0/3] Document intent for supported build platforms and bump min glib to 2.42

["Daniel P. Berrangé" <berrange@redhat.com>]

CC'ing xen-devel in case Xen maintainers have a need for something that
will that conflict with this proposal wrt supported build platforms.

On Fri, May 04, 2018 at 05:00:23PM +0100, Daniel P. Berrangé wrote:
> This short series is a followup the discussions around min glib version
> when Olaf found we had accidentally increased the min glib by using a
> newer function:
> 
>   https://lists.gnu.org/archive/html/qemu-devel/2018-04/msg02699.html
> 
> Some key points from that thread
> 
>   - Although we have a docker job that tries to test the min glib
>     version is adhered to, that's only run post-build, not by Peter's
>     merge tests, nor by patchew.
> 
>   - The docker min glib test failed to detect the problem anyway
>     because RHEL had backported the symbol in question.
> 
>   - The docker min glib test only builds with certain configure
>     options so isn't foolproof.
> 
>   - The modern distros we implicitly care about have way newer glib
>     than 2.22
> 
>   - Peter's OS-X build host previously had 2.22, but after switching
>     from fink to homebrew now has 2.56
> 
>   - I suggested following libvirt's lead in writing a policy for how
>     we pick supported OS targets to inform maintainers when min versions
>     can be increased.
> 
> This series writes such a document largely based on one I wrote for
> libvirt with a few changes, largely around OS-X and *BSD. Note it
> is not meant to be an exhaustive list of distros we'll build on, rather
> a representative selection, so that we can identify the range of 3rd
> party library versions we need to care about. So if your favourite
> distro is missing, dont be alarmed, as it probably ships similar
> vintage software to one of those listed - if not feel free to suggest
> additions.
> 
> Based on that doc and https://repology.org/metapackage/glib/versions,
> I identified that we could feasibly set min glib to 2.42. Note that
> this would be dropping RHEL-6 as a build host (RHEL-6.0 came out in
> 2010 so that's reasonable to drop IMHO). It would still cover 2 major
> Debian versions and 2 most recent Ubuntu LTS (16.04, 18.04, but *not*
> 14.04). This min glib lets us remove almost all our compat code.
> 
> Most interestingly, thanks tothe new min version being greater than
> 2.32, we can now use GLIB_VERSION_MAX_ALLOWED to validate the correct
> API usage according to our min version:
> 
>   https://developer.gnome.org/glib/stable/glib-Version-Information.html#GLIB-VERSION-MAX-ALLOWED:CAPS
> 
> This means that *all* our CI jobs & developer builds will be enforcing
> the min version, so means very many more conditionally built features
> will get their build validated against min glib version. This would
> do a much better job of catching mistakes than our min-glib docker
> job, making that obsolete.
> 
> Daniel P. Berrangé (3):
>   qemu-doc: provide details of supported build platforms
>   glib: bump min required glib library version to 2.42
>   glib: enforce the minimum required version and warn about old APIs
> 
>  configure               |   6 +-
>  include/glib-compat.h   | 362 ++++++------------------------------------------
>  qemu-doc.texi           |  68 +++++++++
>  tests/test-qmp-event.c  |   2 +-
>  tests/tpm-emu.h         |   4 +-
>  tests/vhost-user-test.c |   4 +-
>  trace/simple.c          |   6 +-
>  7 files changed, 123 insertions(+), 329 deletions(-)
> 
> -- 
> 2.14.3
> 

Regards,
Daniel
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