Re: [dpdk-dev] [PATCH v3] mk: filter duplicate configuration entries

[Bruce Richardson <bruce.richardson@intel.com>]

On Wed, Jul 06, 2016 at 09:57:01AM +0100, Ferruh Yigit wrote:
> On 7/6/2016 9:12 AM, Bruce Richardson wrote:
> > On Wed, Jul 06, 2016 at 07:37:45AM +0200, Christian Ehrhardt wrote:
> >> *updates in v3*
> >> - replace tac with sed '1!G;h;$!d' to avoid build time dependency
> >>
> >> *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..d031bf4 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) ; \
> >> +		sed '1!G;h;$$!d' $(RTE_OUTPUT)/.config_tmp > $(RTE_OUTPUT)/.config_tmp_reverse ; \
> >> +		awk --field-separator '=' '!/^#/ {if (!seen[$$1]) {print ($$0)}; seen[$$1]=1;} \
> >> +			/^#/ {print($$0)}' $(RTE_OUTPUT)/.config_tmp_reverse \
> >> +			| sed '1!G;h;$$!d' > $(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 ; \
> >> -- 
> > 
> > Given the length and complexity of the work being done here, using some pretty
> > fancy sed and awk features, I feel that the comment at the top should be
> > expanded to actually explain what is being done and how. I would also include
> > in that explanation how sed is being used to reverse a file. Personally, I
> > would have preferred to keep the dependency on tac for a readability perspective.
> > 
> 
> By using sed, I didn't really mean using sed instead of tac, but
> something close to first version of this patch [1], these are just
> different ways of doing same thing.
> 
> I don't know how common "tac" is, but even a box breaks build because
> off missing tac, that is problem, specially this change is not a must
> but a good to have.
> 
> [1]
> for config in $$(grep -v "^#" $(RTE_OUTPUT)/.config_tmp | cut -d"=" -f1
> | sort | uniq -d); do \
>     while [ $$(grep "^$${config}=" $(RTE_OUTPUT)/.config_tmp -c ) -gt 1
> ]; do \
>         sed -i "0,/^$${config}=/{//d}" $(RTE_OUTPUT)/.config_tmp; \
>     done; \
> done; \
> 

Well, at least on my Fedora box, tac is part of coreutils, so it's probably
pretty widespread on Linux. Unfortunately, it's not available out-of-the-box
on FreeBSD.

/Bruce