Re: [dpdk-dev] [PATCH v2] mk: filter duplicate configuration entries

[Ferruh Yigit <ferruh.yigit@intel.com>]

On 6/30/2016 1:00 PM, Christian Ehrhardt wrote:
> *updates in v2*
> - move to .config target
> - fix usage order of tac
> - simplify inner section by only using awk (instead of awk+loop+bash+sed)
> 
> Due to the hierarchy and the demand to keep the base config showing all
> options, some config keys end up multiple times in the .config file.
> 
> Due to the way the actual config is sourced only the last entry is
> important. That can confuse people changing values in .config which
> are then ignored.
> 
> A suggested solution was to filter for duplicates at the end of the
> actual config step which is implemented here.
> 
> Signed-off-by: Christian Ehrhardt <christian.ehrhardt@canonical.com>
> ---
>  mk/rte.sdkconfig.mk | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/mk/rte.sdkconfig.mk b/mk/rte.sdkconfig.mk
> index a3acfe6..6c46122 100644
> --- a/mk/rte.sdkconfig.mk
> +++ b/mk/rte.sdkconfig.mk
> @@ -79,11 +79,17 @@ $(RTE_OUTPUT):
>  ifdef NODOTCONF
>  $(RTE_OUTPUT)/.config: ;
>  else
> +# Generate config from template, if there are duplicates keep only the last
>  $(RTE_OUTPUT)/.config: $(RTE_CONFIG_TEMPLATE) FORCE | $(RTE_OUTPUT)
>  	$(Q)if [ "$(RTE_CONFIG_TEMPLATE)" != "" -a -f "$(RTE_CONFIG_TEMPLATE)" ]; then \
>  		$(CPP) -undef -P -x assembler-with-cpp \
>  		-ffreestanding \
>  		-o $(RTE_OUTPUT)/.config_tmp $(RTE_CONFIG_TEMPLATE) ; \
> +		tac $(RTE_OUTPUT)/.config_tmp > $(RTE_OUTPUT)/.config_tmp_reverse ; \
Now we are adding new binary dependency (tac) to build system and we now
create a interim file, as far as I understand which is required to use awk.
Although this is a nice piece of awk command, I am not sure if sed
alternative or this is better because of above two issues. This is a
question that I have more than a comment against one to another.

If you prefer to use this one, I confirmed that this works fine.

> +		awk --field-separator '=' '!/^#/ {if (!seen[$$1]) {print ($$0)}; seen[$$1]=1;} \
> +			/^#/ {print($$0)}' $(RTE_OUTPUT)/.config_tmp_reverse \
> +			| tac > $(RTE_OUTPUT)/.config_tmp ; \
> +		rm $(RTE_OUTPUT)/.config_tmp_reverse ; \
>  		if ! cmp -s $(RTE_OUTPUT)/.config_tmp $(RTE_OUTPUT)/.config; then \
>  			cp $(RTE_OUTPUT)/.config_tmp $(RTE_OUTPUT)/.config ; \
>  			cp $(RTE_OUTPUT)/.config_tmp $(RTE_OUTPUT)/.config.orig ; \
>