[dpdk-dev] [PATCH v1 5/6] fix missing includes in exported headers

[Bruce Richardson]

On Thu, Dec 21, 2017 at 02:00:04PM +0100, Adrien Mazarguil wrote:
> Many exported headers rely on definitions found in rte_config.h without
> including it, as shown by the following command:
> 
>  grep -L '^#include <rte_config.h>' -- \
>   $(grep -Rl \
>     $(sed -n '/^#define \([^ ]\+\).*$/{s//\1/;H;};${x;s/\n//;s/\n/\\|/g;p;}' \
>       build/include/rte_config.h) \
>     -- build/include/)
> 
> We cannot assume external applications will include rte_config.h on their
> own, neither directly nor through a -include parameter like DPDK does
> internally.
> 
> This not only causes obvious compilation failures that can be reproduced
> with check-includes.sh such as:
> 
>  [...]/rte_memory.h:88:43: error: ‘RTE_CACHE_LINE_SIZE’ was not declared in
>      this scope
>   #define __rte_cache_aligned __rte_aligned(RTE_CACHE_LINE_SIZE)
>                                             ^
> 
> It also results in less visible issues, for instance rte_hash_crc.h relying
> on RTE_ARCH_X86_64's presence to provide dedicated inline functions.
> 
> This patch partially reverts the commit below and adds missing include
> lines to the remaining files.
> 
> Fixes: f1a7a5c5f404 ("remove include of generated config header")
> Cc: Thomas Monjalon <thomas at monjalon.net>
> 
> Signed-off-by: Adrien Mazarguil <adrien.mazarguil at 6wind.com>
> ---

Hi Adrien,

Just FYI, when we move to the new DPDK build system and pass the
necessary build meta-data to the application using pkg-config, this
should be a non-issue, as the pkg-config information will include the
"-include rte_config.h" parameter.

When investigating that, I also tried this approach of adding rte_config
to files explicitly but it did not work for me as expected, as there
were cases where the build was depending upon the rte_config.h always
being the first include in the file. Normally, the rte_* headers should
be last included, so putting it at the top just didn't seem right to me.
I don't remember the specifics, but it was something like using the RTE_
defines to determine which system header file to use e.g. BSD vs Linux.
However, this may be an internal DPDK-build restriction rather than one
that would affect user-apps our or examples.

So, with transitioning to meson and pkg-config, this issue becomes less
significant.

/Bruce