[Buildroot] [PATCH] core/printvars: allow dumping a set of variables

[Arnout Vandecappelle <arnout@mind.be>]

On 04-11-15 20:40, Yann E. MORIN wrote:
> Dumping our 176164 variables can take quite some time (~12s here). What
> takes the most time is sorting the variables (~9s), followed by the
> parsing of our Makefiles (~3s), with the actual printing in the noise.
> 
> However, sometimes only one or a few variables are needed. For example,
> one may want to retrieve the Linux build dir from a post-build hook (to
> get the Linux' actual .config after our fixups and check for various
> features).
> 
> Add the possibility to only dump the variables listed in $(VAR) which
> must be passed as a make argument, like so:
> 
>     $ make -s printvars VARS="LINUX_DIR TOPDIR O"
>     LINUX_DIR=/home/ymorin/dev/buildroot/O/build/linux-4.3 ($(BUILD_DIR)/$(LINUX_BASE_NAME))
>     O=/home/ymorin/dev/buildroot/O/. (/home/ymorin/dev/buildroot/O/.)
>     TOPDIR=/home/ymorin/dev/buildroot/buildroot (/home/ymorin/dev/buildroot/buildroot)
> 
> This is much faster (the time is just about the time it takes to parse
> our Makefiles, 3s here) and easier to parse.
> 
> Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>

Acked-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>

 I was going to say you forgot to update the documentation, but there isn't any...

 Regards,
 Arnout

> ---
>  Makefile | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/Makefile b/Makefile
> index 6d34ee2..7b152c7 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -832,9 +832,10 @@ ifeq ($(NEED_WRAPPER),y)
>  endif
>  
>  # printvars prints all the variables currently defined in our Makefiles
> +# or only the variables specified in $(VARS)
>  printvars:
>  	@$(foreach V, \
> -		$(sort $(.VARIABLES)), \
> +		$(sort $(if $(VARS),$(VARS),$(.VARIABLES))), \
>  		$(if $(filter-out environment% default automatic, \
>  				$(origin $V)), \
>  		$(info $V=$($V) ($(value $V)))))
> 


-- 
Arnout Vandecappelle                          arnout at mind be
Senior Embedded Software Architect            +32-16-286500
Essensium/Mind                                http://www.mind.be
G.Geenslaan 9, 3001 Leuven, Belgium           BE 872 984 063 RPR Leuven
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