[dpdk-dev] [PATCH v2] doc: announce API changes for Windows compatibility
John Alexander
John.Alexander at datapath.co.uk
Thu Mar 11 17:19:20 CET 2021
> -----Original Message-----
> From: dev <dev-bounces at dpdk.org> On Behalf Of Dmitry Kozlyuk
> Sent: 10 March 2021 23:54
> To: dev at dpdk.org
> Cc: Ferruh Yigit <ferruh.yigit at intel.com>; Pallavi Kadam
> <pallavi.kadam at intel.com>; Dmitry Malloy <dmitrym at microsoft.com>;
> Narcisa Ana Maria Vasile <navasile at linux.microsoft.com>; Stephen
> Hemminger <stephen at networkplumber.org>; Tyler Retzlaff
> <roretzla at linux.microsoft.com>; Declan Doherty
> <declan.doherty at intel.com>; Fiona Trahe <fiona.trahe at intel.com>; Ashish
> Gupta <ashish.gupta at marvell.com>; Dmitry Kozlyuk
> <dmitry.kozliuk at gmail.com>; Ray Kinsella <mdr at ashroe.eu>; Neil Horman
> <nhorman at tuxdriver.com>
> Subject: [dpdk-dev] [PATCH v2] doc: announce API changes for Windows
> compatibility
>
> CAUTION: This email originated from outside of the organization. Do not click
> links or open attachments unless you recognize the sender and know the
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>
> Windows socket headers define `s_addr`, `min`, and `max` macros which
> break structure definitions containing fields with one of these names.
> Undefining those macros would break some consumers as well.
>
> 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 */
>
> It is proposed to rename the conflicting fields on DPDK side, because Win32
> API has wider use and is slower and harder to change.
>
> New names are left unspecified, open suggestions:
>
> * `struct rte_ether_hdr` (by Stephen Hemminger):
>
> * `s_addr` -> `ether_shost`
> * `d_addr` -> `ether_dhost` (for consistency)
>
> * `struct rte_param_log2_range`, `struct rte_crypto_param_range`:
>
> * `min` -> `minimum`
> * `max` -> `maximum`
The min/max macros in the Windows headers cause issues with C++ projects also (breaks std::min/std::max). The fix there is to "#define NOMINMAX" prior to including windows.h, maybe that's appropriate here too?
>
> For `s_addr`, a workaround is possible to use it until 21.11.
> 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).
>
> Workaround for `s_addr` is to define `struct rte_ether_hdr` in such a away
> that it can be used with or without `s_addr` macro (as defined on Windows):
>
> #pragma push_macro("s_addr")
> #ifdef s_addr
> #undef s_addr
> #endif
>
> struct rte_ether_hdr {
> struct rte_ether_addr d_addr; /**< Destination address. */
> RTE_STD_C11
> union {
> struct rte_ether_addr s_addr; /**< Source address. */
> struct {
> struct rte_ether_addr S_un;
> /**< MUST NOT be used directly, only via s_addr */
> } S_addr;
> /**< MUST NOT be used directly, only via s_addr */
> };
> uint16_t ether_type; /**< Frame type. */
> } __rte_aligned(2);
>
> #pragma pop_macro("s_addr")
>
> Signed-off-by: Dmitry Kozlyuk <dmitry.kozliuk at gmail.com>
> ---
> v2: * Propose to rename all problematic fields identified so far.
> * Leave future names unspecified, no need to promise now.
> * Propose better names for MAC addresses (Stephen Hemminger).
>
> Thread about `s_addr` workaround:
> https://mails.dpdk.org/archives/dev/2021-March/200700.html
> Tyler Retzlaff confirmed offline that Microsoft took similar approach.
>
> 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 64629e0641..854618f091 100644
> --- a/doc/guides/rel_notes/deprecation.rst
> +++ b/doc/guides/rel_notes/deprecation.rst
> @@ -130,3 +130,12 @@ 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 20.11 to avoid conflict with Windows Sockets
> headers.
> +
> +* compressdev: ``min`` and ``max`` fields of ``rte_param_log2_range``
> +structure
> + will be renamed in DPDK 20.11 to avoid conflict with Windows Sockets
> headers.
> +
> +* cryptodev: ``min`` and ``max`` fields of ``rte_crypto_param_range``
> +structure
> + will be renamed in DPDK 20.11 to avoid conflict with Windows Sockets
> headers.
> --
> 2.29.2
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