Re: [dpdk-dev] [PATCH 0/5] examples: add a new makefile to build all examples

[Olivier MATZ <olivier.matz@6wind.com>]

Hi Neil,

First, thank you for your reviews.

On Friday, April 25, 2014 10:05:26 AM Neil Horman wrote:
> > After applying the patches, it is possible to build all examples by doing
> > the following:
> >   user@droids:~/dpdk.org$ cd examples
> >   user@droids:~/dpdk.org/examples$ make RTE_SDK=${PWD}/.. \
> >       RTE_TARGET=x86_64-default-linuxapp-gcc
> 
> What you actually want here is RTE_TARGET=build, as the Makefile looks for
> the ${RTE_TARGET}/.config file, it doesn't just parse whatever target file
> you specify.
> 
> That begs the bigger point, RTE_TARGET will always be =build, so why not
> just add a top level make rule for the examples subdirectory, then RTE_SDK
> and RTE_TARGET will just be automatically set.

When we compile an example or an external application, RTE_SDK references
a binary DPDK, or more precisely a DPDK source workspace that has been
compiled with "make install T=my-targets".

You're right that RTE_TARGET corresponds to the name of the build directory
but the logic is that the name of the directory is the name of the target.

To be clearer, the commit log should probably be updated with the
following list of commands:

  user@droids:~/dpdk.org$ make install T=x86_64-default-linuxapp-gcc
  user@droids:~/dpdk.org$ cd examples
  user@droids:~/dpdk.org/examples$ make RTE_SDK=${PWD}/.. \
        RTE_TARGET=x86_64-default-linuxapp-gcc

About adding a top level makefile rule, it's a good idea as it can
be documented in "make help", but I wasn't very confident about where
to put the output files. I can check if doing something like below is
possible or too complex:

  user@droids:~/dpdk.org$ make install T=x86_64-default-linuxapp-gcc
  user@droids:~/dpdk.org$ cd x86_64-default-linuxapp-gcc
  user@droids:~/dpdk.org/x86_64-default-linuxapp-gcc$ make examples
  # generate examples in $PWD/examples

Regards,
Olivier