Re: [XEN PATCH v7 42/51] build: grab common EFI source files in arch specific dir

[Anthony PERARD <anthony.perard@citrix.com>]

On Mon, Oct 18, 2021 at 10:48:26AM +0200, Jan Beulich wrote:
> On 15.10.2021 18:29, Anthony PERARD wrote:
> > On Thu, Oct 14, 2021 at 10:51:44AM +0200, Jan Beulich wrote:
> >> On 24.08.2021 12:50, Anthony PERARD wrote:
> >>> --- a/xen/arch/arm/efi/Makefile
> >>> +++ b/xen/arch/arm/efi/Makefile
> >>> @@ -1,4 +1,10 @@
> >>>  CFLAGS-y += -fshort-wchar
> >>> +CFLAGS-y += -I$(srctree)/common/efi
> >>
> >> Perhaps another opportunity for -iquote?
> > 
> > Yes.
> > 
> >>>  obj-y += boot.init.o pe.init.o ebmalloc.o runtime.o
> >>>  obj-$(CONFIG_ACPI) +=  efi-dom0.init.o
> >>> +
> >>> +$(obj)/%.c: common/efi/%.c
> >>> +	$(Q)cp -f $< $@
> >>
> >> In case both trees are on the same file system, trying to hardlink first
> >> would seem desirable. When copying, I think you should also pass -p.
> > 
> > I don't know if doing an hardlink is a good thing to do, I'm not sure of
> > the kind of issue this could bring. As for -p, I don't think it's a good
> > idea to copy the mode, ownership, and timestamps of the source file, I'd
> > rather have the timestamps that Make expect, e.i. "now".
> 
> Why would "now" be correct (or expected) in any way? The cloned file is no
> different from the original. Nevertheless I agree that -p is not ideal;
> it's just that the more fine grained option to preserve just the timestamp
> is non-standard afaik. You could try that first and fall back to -p ...
> Otherwise, failing hard linking and using "cp -p", I'm afraid I'd prefer
> symlinking despite the arguments against it that you name in the
> description.

I guess I'm missing something, is there a reason to keep/copy the
timestamps of the original files?

> Might be good to have someone else's view here as well.

Indeed.

-- 
Anthony PERARD