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

Thomas Petazzoni thomas.petazzoni at free-electrons.com
Wed Nov 4 20:45:56 UTC 2015


Dear Yann E. MORIN,

On Wed,  4 Nov 2015 20:40:42 +0100, 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 at free.fr>

I haven't thought about the implementation, but it possible to support
wildcards, like LIBFOO_* or LIBFOO_% ?

Thomas
-- 
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com


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