[dpdk-dev] [EXT] [PATCH v3] doc: announce API changes for Windows compatibility

[Akhil Goyal]

> Windows system headers define `s_addr`, `min`, and `max` macros which
> break structure definitions containing fields with one of these names.
> Undefining those macros would break consumer code that relies on them.
> 

>From the commit message the requirement for changing the structure definitions
Is not clear. Please note that 'min' - 'max' are not macros. These are variables of a
structure which should not break any other structure/Macro in windows.

> Example 1:
> 
>     #include <winsock2.h>
>     #include <rte_ether.h>
>     struct in_addr addr;
>     /* addr.s_addr = 0;     ERROR: s_addr undefined by DPDK */
> 
> Example 2:
> 
>     #include <rte_ether.h>
>     #include <winsock2.h>
>     struct rte_ether_hdr eh;
>     /* eh.s_addr.addr_bytes[0] = 0;     ERROR: `addr_s` is a macro */
> 
> Commit 6c068dbd9fea ("net: work around s_addr macro on Windows")
> modified definition of `struct rte_ether_hdr` to avoid the issue.
> However, the workaround assumes `#define s_addr S_addr.S_un`
> in Windows headers, which is not a part of official API.
> It also complicates the definition of `struct rte_ether_hdr`.
> 
> For `min` and `max`, no workaround seems available. If cryptodev or
> compressdev is going to be enabled on Windows before 21.11, the only
> option seems to use a new name on Windows (using #ifdef).
> 
> It is proposed to rename the conflicting fields on DPDK side,
> because Win32 API has wider use and is slower and harder to change.
> Exact new names are left for further discussion.
> 
> Signed-off-by: Dmitry Kozlyuk <dmitry.kozliuk at gmail.com>
> Acked-by: Khoa To <khot at microsoft.com>
> ---
> v3: fix typos (Ferruh), remove naming speculation,
>     replace workaround snippet with commit reference.
> 
>  doc/guides/rel_notes/deprecation.rst | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/doc/guides/rel_notes/deprecation.rst
> b/doc/guides/rel_notes/deprecation.rst
> index 9584d6bfd7..cc6e8db92c 100644
> --- a/doc/guides/rel_notes/deprecation.rst
> +++ b/doc/guides/rel_notes/deprecation.rst
> @@ -147,3 +147,12 @@ Deprecation Notices
>  * cmdline: ``cmdline`` structure will be made opaque to hide platform-
> specific
>    content. On Linux and FreeBSD, supported prior to DPDK 20.11,
>    original structure will be kept until DPDK 21.11.
> +
> +* net: ``s_addr`` and ``d_addr`` fields of ``rte_ether_hdr`` structure
> +  will be renamed in DPDK 21.11 to avoid conflict with Windows Sockets
> headers.
> +
> +* compressdev: ``min`` and ``max`` fields of ``rte_param_log2_range``
> structure
> +  will be renamed in DPDK 21.11 to avoid conflict with Windows Sockets
> headers.
> +
> +* cryptodev: ``min`` and ``max`` fields of ``rte_crypto_param_range``
> structure
> +  will be renamed in DPDK 21.11 to avoid conflict with Windows Sockets
> headers.
> --
> 2.29.3