Re: [dpdk-dev] [PATCHv2] include: fix sys/queue.h.

[William Tu <u9012063@gmail.com>]

On Wed, Aug 11, 2021 at 8:50 AM Dmitry Kozlyuk <dmitry.kozliuk@gmail.com> wrote:
>
> Hi William,
>
> 2021-08-11 20:46 (UTC+0000), William Tu:
> > Currently there are a couple of header files include 'sys/queue.h',
> > which is a POSIX functionality.  When compiling DPDK with OVS on
> > Windows, we encountered issues such as, found the missing header.
> > In file included from ../lib/dpdk.c:27:
> > C:\temp\dpdk\include\rte_log.h:24:10: fatal error: 'sys/queue.h' file
> > not found
> >
> > The patch fixes it by 1) removing the #include <sys/queue.h> from
> > a couple of headers, replace it with  #include <rte_os.h>, and
> > 2) include sys/queue.h in the rte_os.h. As a result, for Linux/BSD,
> > it is using the sys/queue.h from its POSIX library, and for Windows,
> > DPDK will use the bundled sys/queue.h.
> >
> > 1) fixes the case that DPDK library shouldn't export POSIX functionality
> > into the environment (symbols, macros, headers etc), which cause definitions
> > clashing with the application.
> > 2) fixes the case that DPDK should depend only on the C library and not
> > require POSIX functionality from the underlying system.
>
> Sorry, this is not exactly what was suggested here:
>
>         http://inbox.dpdk.org/dev/20210811013325.34c36220@sovereign/
>
> The point was not to install <sys/queue.h>. Its full content is not needed
> for DPDK interface, only for implementation. Public headers only need a
> handful of macros for list/tailq heads and links. Those macros should be
> provided by DPDK, with RTE_ prefix. For Linux and FreeBSD it will just be:
>
>         #include <sys/queue.h>
>         #define RTE_TAILQ_ENTRY(type) TAILQ_ENTRY(type)
>         /* ... */
>
> For Windows you would have to copy definitions from <sys/queue.h>
> to some public header, <rte_os.h> seems OK. All public headers that need
> <sys/queue.h> macros must have them replaced with RTE_ version.
> Implementation remains unchanged. No new files need to be installed,
> because when DPDK is built on Windows, it uses the bundled <sys/queue.h>,
> and when it is installed, only RTE_ macros you created are visible.
>
> Macro documentation should clearly state that they are compatible with system
> <sys/queue.h> for Linux and FreeBSD, and for Windows they are compatible with
> the version used during build.
>
> +Bruce, David, Ray, Tyler to confirm/object the idea.
>
> > There are still a couple of headers using sys/queue.h, ex:
> > rte_bus_pci.h. Since it's not been used in Windows yet, we can
> > fix them later.
>
> Another item I think of is a checkpatch rule to prohibit TAILQ_xxx, etc
> macro in public headers after replacing them all.
>
> > Suggested-by: Nick Connolly <nick.connolly@mayadata.io>
> > Suggested-by: Dmitry Kozliuk <Dmitry.Kozliuk@gmail.com>
> > Signed-off-by: William Tu <u9012063@gmail.com>
> > ---
> > v1->v2:
> >   - follow the suggestion by Nick and Dmitry
> >   - http://mails.dpdk.org/archives/dev/2021-August/216304.html
>
> Please send new versions as replies to the previous ones:
>
>         git send-email --in-reply-to MSGID ...
>
> https://doc.dpdk.org/guides/contributing/patches.html

Hi Dmitry,
Thanks! I see your point now. I will work on the next patch.
William