Re: [Xen-devel] [PATCH] tools/configure: Check if pixman is present on the system

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Wed, 14 Jan 2015, Wei Liu wrote:
> On Wed, Jan 14, 2015 at 10:39:45AM +0000, Ian Campbell wrote:
> > On Wed, 2015-01-14 at 07:11 +0000, Jan Beulich wrote:
> > > >>> Julien Grall <julien.grall@xxxxxxxxxx> 01/13/15 7:17 PM >>>
> > > >QEMU upstream requires the use of pixman. When pixman is not present the
> > > >system, the configure of QEMU will fail with:
> > > >
> > > >ERROR: pixman not present. Your options:
> > > >(1) Preferred: Install the pixman devel package (any recent
> > > >distro should have packages as Xorg needs pixman too).
> > > >(2) Fetch the pixman submodule, using:
> > > >git submodule update --init pixman
> > > >
> > > >I think we can use by default the version on the system. So check it
> > > >a Xen configuration time to avoid a build issue later.
> > > 
> > > Since qemu building isn't a required part of building the tools, is a 
> > > check in
> > > the tools configure process really an appropriate thing to do?
> > 
> > It's quite annoying as a user to have configure appear to succeed and
> > then the build to fail due to a missing dependency (whether in a 3rd
> > party component or not).
> > 
> > We could make this check conditional on --with-qemu-system not being
> > given, but given the library is readily available I don't think its the
> > end of the world to have a potentially unnecessary check.
> > 
> > A far more heavy weight (but probably better) solution would be to
> > arrange for the clone (and necessary downloads) + submodule configure to
> > happen at configure rather than build time. That's a much bigger job
> > though and I wouldn't expect anyone to take that on unless they are
> > super duper keen.
> > 
> 
> Or we can state clearly in README / INSTALL that Xen's configure doesn't
> check for external projects' dependencies so that we don't end up adding
> check for every new dependency in QEMU. Just my 2 cents.

I think it would be use unfriendly.

In the vast majority of cases users are going to try to build QEMU as
part of the Xen build, so we might as well try to make it a bit easier
for them listing all dependencies up front.

If I were to download the tarball of a given project, pass all the
configure checks, only to find that the build still fails because of a
missing dependency, I would be quite annoyed.

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