On Tue, Jul 13, 2021 at 09:49:09AM +0300, Eli Britstein wrote:

In rte_pktmbuf_mtod_offset macro, there is a casting from char * to type
't', which may cause cast-align warning when using gcc flags
'-Werror -Wcast-align':

.../include/rte_mbuf_core.h:723:3: error: cast increases required alignment
    of target type [-Werror=cast-align]
  723 |  ((t)((char *)(m)->buf_addr + (m)->data_off + (o)))
      |   ^

As the code assumes correct alignment, add first a (void *) casting, to
avoid the warning.

Fixes: af75078fece3 ("first public release")
Cc: stable@dpdk.org

Signed-off-by: Eli Britstein <redacted>

My initial thinking was that it's the problem of the application: if
-Werror=cast-align is used, it is up to the application to cast the
return value of rte_pktmbuf_mtod_offset() to (void *) before casting it
to the network type.

But, if I understand correctly, the problem is not about the application
code itself, but about inlined code in the header files of dpdk
(i.e. compiling an empty C file that just includes the dpdk headers with
-Werror=cast-align). Is it correct? If yes I think it should be
highlighted in the commit log.

Out of curiosity, how did you find the errors? I mean, is it possible
that some casts are missing some other headers, or is this patchset
exhaustive?

Thanks,
Olivier