Re: [Qemu-devel] [PATCH 02/12] build-sys: silence make by default

[Eric Blake]

On 12/07/2017 06:58 PM, Marc-André Lureau wrote:
> In particular, do not print anything when there is nothing to do, in
> particular, after a successful build:

Do we need both 'in particular'?

> 
> $ make
> make[1]: '/home/elmarco/src/qemu/build/capstone/libcapstone.a' is up to date.
> 
> Signed-off-by: Marc-André Lureau <address@hidden>
> ---
>  rules.mak | 5 +++++
>  1 file changed, 5 insertions(+)

Yay!  I've been bothered by this.

You may want to add that the noise is conditional on whether you have
capstone-devel installed.

However,

> 
> diff --git a/rules.mak b/rules.mak
> index 6e943335f3..b760d54908 100644
> --- a/rules.mak
> +++ b/rules.mak
> @@ -131,6 +131,11 @@ modules:
>  # If called with only a single argument, will print nothing in quiet mode.
>  quiet-command = $(if $(V),$1,$(if $(2),@printf "  %-7s %s\n" $2 $3 && $1, 
> @$1))
>  
> +makeflags_ = $(makeflags_0)
> +makeflags_0 = --no-print-directory -s

Why the mix of long option and short option? Would it be more legible to
use two long options?

In my testing of your patch, '-s' alone also silenced things
(admittedly, when libcapstone.a is up-to-date).  What is
--no-print-directory adding?

/me goes digging

Hmm, we already have this in Makefile:

SUBDIR_MAKEFLAGS=$(if $(V),,--no-print-directory) BUILD_DIR=$(BUILD_DIR)

So maybe our problem is that we are forgetting to feed SUBDIR_MAKEFLAGS
to our sub-make that builds libcapstone.a?

Next, why is -s silencing the "is up to date" message?  Per 'make
--help', -s controls whether recipes are echoed - but that doesn't seem
to be a recipe that was echoed.  Furthermore, the make manual mentions
that -s is automatically added to MAKEFLAGS if it was present in the
command line; are we accidentally silencing too much (if the user wants
to do 'make -s V=1' to get JUST command lines but not the make noise)?

> +makeflags_1 =
> +MAKEFLAGS += $(makeflags_$(V))
> +

So I'm not yet convinced that this is the right place, or if it is too
heavy of a hammer.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org

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