Re: deprecation of in-tree builds

From: "Daniel P. Berrangé" <berrange@redhat.com>
To: Peter Maydell <peter.maydell@linaro.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
	Markus Armbruster <armbru@redhat.com>,
	QEMU Developers <qemu-devel@nongnu.org>
Subject: Re: deprecation of in-tree builds
Date: Mon, 30 Mar 2020 14:42:12 +0100	[thread overview]
Message-ID: <20200330134212.GO236854@redhat.com> (raw)
In-Reply-To: <CAFEAcA-9U=EAXAtPDh_AnO3eUbM_jcRBuf4x=0Rec0EC-v2mNA@mail.gmail.com>

On Mon, Mar 30, 2020 at 02:31:52PM +0100, Peter Maydell wrote:
> On Mon, 30 Mar 2020 at 14:26, Markus Armbruster <armbru@redhat.com> wrote:
> >
> > Peter Maydell <peter.maydell@linaro.org> writes:
> >
> > > AIUI from Paolo, the intention is to deprecate and eventually
> > > stop supporting "in-tree" builds, so that the only option is
> > > building in a separate build directory. I thought we should
> > > probably mention that in the 5.0 changelog, so I wrote up some
> > > text:
> > >
> > > https://wiki.qemu.org/ChangeLog/5.0#Build_Information
> >
> > Overdue.  Thanks for doing this!
> >
> > > Suggestions for changes/comments etc welcome.
> >
> > Looks fine to me.
> 
> Consensus in the thread seemed to lean towards having
> the 'configure/make' runes auto-create a build directory;
> if we want to do that we should probably not say anything in
> the release notes, because we'll cause people to change
> unnecessarily. Or at least have them say "We recommend
> out-of-tree builds. In future we might make the commands
> that currently do an in-tree build automatically create
> and use a build directory for you." rather than a blanket
> "we're going to drop this and you should change what you
> do now".
> 
> Thoughts?

When the time comes to switch to Meson, we'll be forcing a
separate build directory & that will also potentially involve
a change in build instructions for users.

So if we expect Meson will arrive in QEMU soon (say before end
of this year), then I'd try to keep changes related to make to
the bare minimum, and have Meson switch as the "flag day" when
developers are forced to adapt their build process. 

IOW, merely warn people that in-tree builds are deprecated and
not tested by the project and enourage switching to out of tree
builds. Dont try to magically create a separate build dir now.

Regards,
Daniel
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