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

[Jan Beulich <jbeulich@xxxxxxxx>]

On 21.10.2021 13:03, Anthony PERARD wrote:
> 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?

Avoidance of confusion is my main aim here. I certainly would be puzzled
to see what looks like a source file to have a time stamp much newer than
expected.

Jan