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

[Dmitry Kozlyuk]

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.

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