Re: [dpdk-dev] [PATCH v2] ABI: Add abi checking utility

[Thomas Monjalon <thomas.monjalon@6wind.com>]

2015-03-04 10:42, Neil Horman:
> On Wed, Mar 04, 2015 at 04:15:18PM +0100, Thomas Monjalon wrote:
> > 2015-03-04 09:39, Neil Horman:
> > > On Wed, Mar 04, 2015 at 01:54:49PM +0100, Thomas Monjalon wrote:
> > > > Hi Neil,
> > > > 
> > > > I remove parts that I agree and reply to those which deserve more discussion.
> > > > 
> > > > 2015-03-04 06:49, Neil Horman:
> > > > > On Tue, Mar 03, 2015 at 11:18:47PM +0100, Thomas Monjalon wrote:
> > > > > > 2015-02-02 13:18, Neil Horman:
> > > > > > > +# Make sure we configure SHARED libraries
> > > > > > > +# Also turn off IGB and KNI as those require kernel headers to build
> > > > > > > +sed -i -e"$ a\CONFIG_RTE_BUILD_SHARED_LIB=y" config/defconfig_$TARGET
> > > > > > > +sed -i -e"$ a\CONFIG_RTE_EAL_IGB_UIO=n" config/defconfig_$TARGET
> > > > > > > +sed -i -e"$ a\CONFIG_RTE_LIBRTE_KNI=n" config/defconfig_$TARGET
> > > > > > 
> > > > > > Why not tuning configuration after make config in .config file?
> > > > > > 
> > > > > Because this way we save a reconfig (from a developer viewpoint), you should run
> > > > > make config again after changing configs, and so this way you save doing that.
> > > > 
> > > > No, you run make config once and update .config file. That's the recommended
> > > > way to configure DPDK.
> > > > defconfig files are default configurations and should stay read-only.
> > > 
> > > They get overwritten when we do the git resets.  Its silly to modify your config
> > > file after you run make config, in the event the make target has to re-read any
> > > modified options and adjust dependent config files accordingly.  I understand
> > > that doesn't happen now, but its common practice for every open source project
> > > in existance.
> > 
> > I'm not sure to understand. Maybe an example would help.
> > By the way, your method works.
> 
> For example, the linux kernel.  The .config file that is generated in the root
> directory is converted to an autoconf.h in parallel with its generation, for
> applications to key off of.  If you change something in .config, you need to run
> make config again so that those changes are reflected into the other
> auto-generated files.  Thats common practice.  So its counter intuitive to
> assume that altering the generated .config file is automatically recognized by
> the rest of the build, without a subsequent make config (be it explicit or and
> implicit dependency of the make all target).

OK thanks, now I better understand how you think about DPDK config.
Note that in Linux you are modifying .config, not the defconfig.
I'm not going to debate how it could be improved now but I think we shouldn't
dynamically modify defconfig files to avoid confusion about their purpose.