[PATCH v5] Makefile: Add build time and compiler info string

[Bin Meng]

On Tue, Oct 19, 2021 at 8:23 AM Alistair Francis
<Alistair.Francis at wdc.com> wrote:
>
> On Mon, 2021-10-18 at 16:06 +0530, Anup Patel wrote:
> > On Mon, Oct 18, 2021 at 3:58 PM Andreas Schwab <schwab at linux-m68k.org>
> > wrote:
> > >
> > > On Okt 18 2021, Anup Patel wrote:
> > >
> > > > Users will have to figure-out/remember a fixed build date when
> > > > using SOURCE_DATA_EPOCH for reproducible builds whereas
> > > > users don't need to do anything when BUILD_INFO is not defined.
> > >
> > > Users who care about reproducible builds already know how to set
> > > SOURCE_DATA_EPOCH.
> > >
> >
> > @Alistair Francis Are you okay removing BUILD_INFO and having it
> > always enabled ?
>
> I think it should be disabled by default.
>
> We have not had a timestamp for awhile and it hasn't impacted people
> too much.
>
> The reproducible build documentation specifically says that timestamps
> are best avoided (https://reproducible-builds.org/docs/timestamps/). I
> think they sum it up well that it doesn't add much value, except for a
> few specific circumstances.
>
> So I don't see a good justification for enabling it by default, even
> with SOURCE_DATE_EPOCH (good catch on the name chage, I missed that).
>

If that, please reword the following part of the commit message as
well as updating the docs regarding "reproducible builds". Having
BUILD_INFO=n does not mean we are reproducible builds by default.

NOTE: `BUILD_INFO=y` will violate "reproducible builds".
So it's ONLY for development and debug purpose, and should NOT be used
in a product which follows "reproducible builds".

Regards,
Bin