[PATCH v1 1/1] doc: announce ethdev ABI change for rte_eth_dev_info.

[Ian Stokes <ian.stokes@intel.com>]

Maximum and minimum MTU values vary between hardware devices. In
hardware agnostic DPDK applications access to such information would
allow a more accurate way of validating and setting supported MTU values on
a per device basis rather than using a defined default for all devices.

The following solution was proposed:

http://mails.dpdk.org/archives/dev/2018-September/110959.html

This patch adds a depreciation notice for ``rte_eth_dev_info`` as new
members will be added to represent min and max MTU values. These can be
added to fit a hole in the existing structure for amd64 but not for 32 bit,
as such ABI change will occur as size of the structure will be impacted.

Signed-off-by: Ian Stokes <ian.stokes@intel.com>
---
 doc/guides/rel_notes/deprecation.rst | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/doc/guides/rel_notes/deprecation.rst b/doc/guides/rel_notes/deprecation.rst
index 34b28234c..da2b1ce15 100644
--- a/doc/guides/rel_notes/deprecation.rst
+++ b/doc/guides/rel_notes/deprecation.rst
@@ -49,6 +49,18 @@ Deprecation Notices
   Target release for removal of the legacy API will be defined once most
   PMDs have switched to rte_flow.
 
+* ethdev: Maximum and minimum MTU values vary between hardware devices. In
+  hardware agnostic DPDK applications access to such information would allow
+  a more accurate way of validating and setting supported MTU values on a per
+  device basis rather than using a defined default for all devices. To
+  resolve this, the following members will be added to ``rte_eth_dev_info``.
+  Note: these can be added to fit a hole in the existing structure for amd64
+  but not for 32 bit, as such ABI change will occur as size of the structure
+  will increase.
+
+  - Member ``uint16_t min_mtu`` the minimum MTU allowed.
+  - Member ``uint16_t max_mtu`` the maximum MTU allowed.
+
 * pdump: As we changed to use generic IPC, some changes in APIs and structure
   are expected in subsequent release.
 
-- 
2.13.6