Re: [XEN PATCH v8 12/47] build: build everything from the root dir, use obj=$subdir

[Anthony PERARD <anthony.perard@xxxxxxxxxx>]

On Tue, Dec 21, 2021 at 08:55:26AM +0100, Jan Beulich wrote:
> On 20.12.2021 12:29, Anthony PERARD wrote:
> > On Thu, Dec 16, 2021 at 11:08:47AM +0000, Anthony PERARD wrote:
> >> On Tue, Dec 07, 2021 at 12:10:34PM +0100, Jan Beulich wrote:
> >>> On 25.11.2021 14:39, Anthony PERARD wrote:
> >>>> --- a/xen/Makefile
> >>>> +++ b/xen/Makefile
> >>>> @@ -22,6 +22,15 @@ export CHECKPOLICY    ?= checkpolicy
> >>>>  export BASEDIR := $(CURDIR)
> >>>>  export XEN_ROOT := $(BASEDIR)/..
> >>>>  
> >>>> +abs_objtree := $(CURDIR)
> >>>> +abs_srctree := $(CURDIR)
> >>>
> >>> Nit: In line with e.g. obj-y I think these would better be abs-srctree and
> >>> abs-objtree.
> >>
> >> I guess that would be fine, we don't need to keep the same spelling that
> >> Kbuild does.
> > 
> > Actually, those two variables are exported, as it appear in the next two
> > lines. Exporting a variable with a dash doesn't work very well as shells
> > may not be able to use them. When make find a variable with a dash in
> > it in the environment, it unexport them.
> > 
> > So, for those two variable, we need to avoid using a dash, so I think
> > keeping the current name is better. (And now, I've find out that there's
> > an issue in the build system, I'll prepare a patch.)
> 
> Oh, sure - if they have to be exported, the names should remain as they are.
> Question of course why they need exporting when by the end of the conversion
> you don't change directories anymore.

So far, the value of those two variables are simple, but they get a bit
more complicated when we introduce out-of-tree build. I would rather
avoid recalculating those values later one and be sure that the values
are the same on recursion.

Thanks,

-- 
Anthony PERARD