Re: [PATCH] tools/libs/guest: fix out of tree builds of libxenguest users

[Jürgen Groß <jgross@xxxxxxxx>]

On 25.09.20 06:59, Jürgen Groß wrote:
> On 24.09.20 22:23, Andrew Cooper wrote:
> > On 23/09/2020 06:24, Juergen Gross wrote:
> > > xenguest.h includes xenctrl_dom.h, which is including the Xen internal
> > > xen/libelf/libelf.h. This results in build failures for components
> > > using libxenguest when being built outside the Xen build environment.
> > >
> > > Fix that by guarding the include of xenctrl_dom.h with
> > > "#ifdef __XEN_TOOLS_".
> > >
> > > Fixes: 7e0165c19387 ("tools/libxc: untangle libxenctrl from 
> > > libxenguest")
> > > Reported-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> > > Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
> > > ---
> > >   tools/libs/guest/include/xenguest.h | 2 ++
> > >   1 file changed, 2 insertions(+)
> > >
> > > diff --git a/tools/libs/guest/include/xenguest.h 
> > > b/tools/libs/guest/include/xenguest.h
> > > index 4643384790..5cd502f644 100644
> > > --- a/tools/libs/guest/include/xenguest.h
> > > +++ b/tools/libs/guest/include/xenguest.h
> > > @@ -22,7 +22,9 @@
> > >   #ifndef XENGUEST_H
> > >   #define XENGUEST_H
> > > +#ifdef __XEN_TOOLS__
> > >   #include <xenctrl_dom.h>
> > > +#endif
> > I have to admit that this doesn't feel right to put into a public header.
> >
> > Can't we split xenctrl_dom in half and merge the relevant subsets into
> > xen{ctrl,guest}.h ?
> Yes, but the xenctrl.h half will be empty :-) (see my patch from Sep
> 9th).
>
> The #ifdef will remain, though.
>
> Another solution would be to make xenctrl_dom.h an internal header
> again which has to be included by every user needing the domain loader
> stuff. Question then is why all of this is part of libxenguest.
>
> Or we could remove the prototype of xc_dom_register_loader() and the
> definition of struct xc_dom_loader from the header and make it private
> to libxenguest, and modify struct xc_dom_image to hold an opaque pointer
> to struct elf_dom_parms instead of having it as a sub-structure. This
> would remove the need to include xen/libelf/libelf.h from xenctrl_dom.h.
> The question would then be how usable the whole stuff is for someone not
> having the layout of struct elf_dom_parms.
I just discovered that currently only 5 elements of struct elf_dom_parms
are being used by libxenguest users in Xen. We could add accessors for
those to libxenguest.

This would be my favorite solution (including the merge of xenctrl_dom.h
into xenguest.h).

> And finally we could split libxenguest and have a libxendomload which
> will be usable Xen internal only.
>
> Any preference?

Juergen