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

[Ian Campbell <Ian.Campbell@citrix.com>]

On Wed, 2015-01-14 at 07:11 +0000, Jan Beulich wrote:
> >>> Julien Grall <julien.grall@linaro.org> 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.

Ian.