Re: Ping: [PATCH 1/9] build: use if_changed more consistently (and correctly) for prelink*.o

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Tue, 22 Sep 2020, Julien Grall wrote:
> Hi Jan,
> 
> On 22/09/2020 11:55, Jan Beulich wrote:
> > On 22.09.2020 11:24, Julien Grall wrote:
> > > On 22/09/2020 09:28, Jan Beulich wrote:
> > > > On 21.09.2020 13:39, Julien Grall wrote:
> > > > > On 21/09/2020 11:17, Jan Beulich wrote:
> > > > > > On 14.09.2020 12:15, Jan Beulich wrote:
> > > > > > > Switch to $(call if_changed,ld) where possible; presumably not
> > > > > > > doing so
> > > > > > > in e321576f4047 ("xen/build: start using if_changed") right away
> > > > > > > was an
> > > > > > > oversight, as it did for Arm in (just) one case. It failed to add
> > > > > > > prelink.o to $(targets), though, causing - judging from the
> > > > > > > observed
> > > > > > > behavior on x86 - undue rebuilds of the final binary (because of
> > > > > > > prelink.o getting rebuild for $(cmd_prelink.o) being empty, in
> > > > > > > turn
> > > > > > > because of .prelink.o.cmd not getting read) during "make
> > > > > > > install-xen".
> > > > > > > 
> > > > > > > Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
> > > > > > > ---
> > > > > > >     xen/arch/arm/Makefile |  4 +++-
> > > > > > >     xen/arch/x86/Makefile | 18 ++++++++++--------
> > > > > > >     2 files changed, 13 insertions(+), 9 deletions(-)
> > > > > > 
> > > > > > May I ask for an Arm-side ack (or otherwise) here, please?
> > > > > 
> > > > > Acked-by: Julien Grall <jgrall@xxxxxxxxxx>
> > > > 
> > > > Thanks. On the Arm side this is actually addressing a (minor) bug,
> > > 
> > > Just to confirm, the bug is: Xen will be rebuilt when it is not
> > > necessary, right?
> > 
> > Yes. When building as non-root but installing as root, this would
> > typically involve an owner change of some of the involved files.
> > That's how I did notice the issue on x86 (after switching to
> > if_changed) in the first place.
> 
> Thanks for the explanation. I think it would be fine to backport.
> @Stefano, what do you think?

I am OK with that