Re: [XEN PATCH v7 12/51] build: avoid building arm/arm/*/head.o twice

[Anthony PERARD <anthony.perard@xxxxxxxxxx>]

On Tue, Aug 24, 2021 at 01:53:11PM +0100, Julien Grall wrote:
> Hi Anthony,
> 
> On 24/08/2021 11:49, Anthony PERARD wrote:
> > head.o is been built twice, once because it is in $(ALL_OBJS) and a
> > second time because it is in $(extra-y) and thus it is rebuilt when
> > building "arch/arm/built_in.o".
> > 
> > Fix this by adding a dependency of "head.o" on the directory
> > "arch/arm/".
> > 
> > Also, we should avoid building object that are in subdirectories, so
> > move the declaration in there. This doesn't change anything as
> > "arch/arm/built_in.o" depends on "arch/arm/$subarch/built_in.o" which
> > depends on $(extra-y), so we still need to depend on
> > "arch/arm/built_in.o".
> 
> head.o as to be right at the beginning of the binary. Will this still be
> guaranteed with this change?

I guess what you want to know is: no change to the final binary.

The layout of the final binary is defined by $(ALL_OBJS), which this
patch doesn't change.

This patch only ask make that when it want to build "head.o", it need
first to build "arm/built_in.o", then "head.o" exist so we ask make to
not do anything in this Makefile.

Thanks,

-- 
Anthony PERARD