Re: [PATCH] kbuild: ensure Make >= 3.82 is used

[Nicolas Schier]

On Wed 14 Dec 2022 11:05:10 GMT, David Laight wrote:
> From: Nicolas Schier
> > Sent: 13 December 2022 03:59
> ...
> > > > diff --git a/Makefile b/Makefile
> > > > index 2dda1e9a717a..66dfc5751470 100644
> > > > --- a/Makefile
> > > > +++ b/Makefile
> > > > @@ -11,6 +11,11 @@ NAME = Hurr durr I'ma ninja sloth
> > > >  # Comments in this file are targeted only to the developer, do not
> > > >  # expect to learn how to build the kernel reading this file.
> > > >
> > > > +# Ensure Make >= 3.82
> 
> Wouldn't it be better to say either:
> 	# Ensure gmake supports 'undefine' (added in 3.82)
> or:
> 	# Building with gmake versions prior to 3.82 fails due to
> 	# bug 'brief description'.
> 	# Check for 'undefine' support as a surrogate for the bug fix.
> 
>     David

'undefine' is not the only feature that has been introduced in make 
3.82 that we use,  e.g. 'private' keyword is used in rust/Makefile but 
'private' is not checkable via .FEATURES.  Checking for 'undefine' in 
.FEATURES is kind of a hack to detect make 3.82, but as written 
earlier, it prevents doing other explicit version comparison like 
$(filter-out 3.80 3.81 3.82 3.99.% $(filter 1.% 2.% 3.*)).

I think $(filter undefine,$(.FEATURES)),) is a sensible compromise.

Kind regards,
Nicolas

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