Re: [PATCH kvmtool 3/6] Makefile: support -s switch

[Will Deacon <will.deacon@arm.com>]

On Fri, Jan 25, 2019 at 06:07:58PM +0000, Andre Przywara wrote:
> "make -s" suppresses normal output, just shows warnings and errors.
> But since we explicitly override the make output with our fancy concise
> version, we miss out on this feature.
> 
> Do as the kernel does and explicitly suppress every normal output when -s
> is given. This helps to spot warnings that scroll out of the terminal
> window too quickly.
> 
> Signed-off-by: Andre Przywara <andre.przywara@arm.com>
> ---
>  Makefile | 16 +++++++++++++++-
>  1 file changed, 15 insertions(+), 1 deletion(-)
> 
> diff --git a/Makefile b/Makefile
> index c4faff66..a68cfcd5 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -2,8 +2,22 @@
>  # Define WERROR=0 to disable -Werror.
>  #
>  
> +ifneq ($(filter 4.%,$(MAKE_VERSION)),)  # make-4
> +ifneq ($(filter %s ,$(firstword x$(MAKEFLAGS))),)
> +  silent=1
> +endif
> +else                                    # make-3.8x
> +ifneq ($(filter s% -s%,$(MAKEFLAGS)),)
> +  silent=1
> +endif
> +endif

Why do we need to do this differently for different versions of Make?
afaict, the kernel manages this using findstring and filter-out.

Will