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Date: Mon, 7 Dec 2009 21:22:17 +0200
From: "Michael S. Tsirkin" <mst@redhat.com>
Message-ID: <20091207192217.GC5734@redhat.com>
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Subject: [Qemu-devel] Re: run make defconfig
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To: Anthony Liguori <anthony@codemonkey.ws>
Cc: qemu-devel@nongnu.org, Juan Quintela <quintela@redhat.com>

On Mon, Dec 07, 2009 at 11:19:26AM -0600, Anthony Liguori wrote:
> Michael S. Tsirkin wrote:
>> OK, I got the "Run make defconfig" message again.
>> I think it used to be re-run automatically: why
>> are we asking the user to do it manually now?
>>   
> It's buggy.  defconfig should only be needed when a new config option is  
> added and the old config doesn't contain it yet.
>
> But we get this message often when a new config option has not been  
> added.  I suspect it has something to do with checks on accessed time  
> against configure and config*.  We probably need to be smarter than that.
>
> Regards,
>
> Anthony Liguori


Could you tell me what is it supposed to do?
Here's code with my commentary:


config-all-devices.mak: $(SUBDIR_DEVICES_MAK)
        $(call quiet-command,cat $(SUBDIR_DEVICES_MAK) | grep =y | sort -u > $@,"  GEN   $@")

# so there's config-all-devices.mak which includes all =y lines from SUBDIR_DEVICES_MAK.

%/config-devices.mak: default-configs/%.mak

# this is run if
# default-configs/%.mak exists and %/config-devices.mak
# is older than default-configs/%.mak

        $(call quiet-command,cat $< > $@.tmp, "  GEN   $@")

# simply cat default-configs/%.mak to a temporary file

        @if test -f $@ ; then \

# check whether %/config-devices.mak exists

          echo "WARNING: $@ out of date." ;\
          echo "Run \"make defconfig\" to regenerate." ; \
          rm $@.tmp ; \

#if yes tell user to run make defconfig and remove temporary
# so why generate in the first place?

         else \
          mv $@.tmp $@ ; \

#if no move temporary to %/config-devices.mak

         fi

defconfig:
        rm -f config-all-devices.mak $(SUBDIR_DEVICES_MAK)

# this removes config-all-devices.mak and all SUBDIR_DEVICES_MAK


Now in targets, we have include config-devices.mak


So my conclusions are:

- The only way to generate config-devices.mak seems to be to copy default-configs.mak
- We get warning each time timestamp for default configs changes.
- Annoyingly, this warning will be present when you run make defconfig itself
  or when you run make clean
 
Proposal: why don't we just make %/config-devices.mak include
default-configs/%.mak? No copy will be necessary.


-- 
MST