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

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

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; \