Re: [Xen-devel] [PATCH 0/3] move libxc and xenstore public headers to include subdir

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

On Thu, 2014-07-10 at 17:48 +0100, Ian Jackson wrote:
> Ian Campbell writes ("Re: [Xen-devel] [PATCH 0/3] move libxc and xenstore 
> public headers to include subdir"):
> > On Thu, 2014-07-10 at 17:36 +0100, Ian Jackson wrote:
> > > It seems to me that, instead, these headers are (or should be) put
> > > into dist/install/,
> > 
> > Definitely not. dist/install is an output directory which only some of
> > our build runes create (basically those which are a shortcut for make
> > install DESTDIR=dist)
> 
> Yes, that's what I meant.  I was using it as a shorthand for the
> relevant part of DESTDIR.

DESTDIR is not set at build time, only at make install time. Its sole
purpose is to install things into it as a pseudo root dirctory for the
users staging/packaging purposes.

It should definitely not be used as part of our own build system.

> > My build scripts for example don't use those rules, instead they do
> >         make -C tools build
> >         dir=$(mktemp -d /tmp/XXXXXX)
> >         make tools-install DESTDIR=${dir}
> > 
> > Lots of distro packaging will do the same.
> 
> Well, then the out-of-tree things should be getting things from there.

Properly out-of-tree things should be getting them from their actal
install locations (/usr/local/include or /usr/include etc), just like
they get every other library header they depend on (modulo things like
pkg-config etc).

> > > and anything out-of-tree which needs them should
> > > be looking for them there.
> > 
> > Properly out of tree things should get them from /usr/{local/,}include
> > which is where they are installed.
> > 
> > This patch is about in-tree things and pseudo-in-tree things like
> > tools/qemu-xen-dir. They are using -Itools/xenstore and picking up
> > xenstore's internal headers alongside the public headers.
> 
> I agree that this is wrong.  But IMO it should be fixed by having
> those things that can't cope (which should be only pseudo-in-tree
> things as you put it) -I$(DESTDIR)/include (or whatever the real thing
> is).

No, $(DESTDIR) must not be used in this way by anything built by Xen's
build targets. Specifically qemu-xen-dir's build cannot and should not
use $(DESTDIR).

If our build process for the qemu integration into the Xen process was
to tell users:
        make build
        make install [DESTDIR=foo]
Now you have Xen. Go and build qemu yourself with:
        clone qemu
        cd qemu
        configure it [using DESTDIR if you want]
        make
then you would be right. But the last four steps here are integrated
into our "make build" and cannot use DESTDIR.

Ian.


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