path: root/doc/guides/nics/mlx5.rst
diff options
authorMoti Haimovsky <>2018-07-12 15:01:31 +0300
committerShahaf Shuler <>2018-07-12 14:34:59 +0200
commit6bf10ab69be027401cc63b99fd30bc91fde525a9 (patch)
tree9db42b208b94826aa243ea0f2636df0f46373430 /doc/guides/nics/mlx5.rst
parent06b1fe3f6d2121009b3b879e92b8cca25d4c0c42 (diff)
net/mlx5: support 32-bit systems
This patch adds support for building and running mlx5 PMD on 32bit systems such as i686. The main issue to tackle was handling the 32bit access to the UAR as quoted from the mlx5 PRM: QP and CQ DoorBells require 64-bit writes. For best performance, it is recommended to execute the QP/CQ DoorBell as a single 64-bit write operation. For platforms that do not support 64 bit writes, it is possible to issue the 64 bits DoorBells through two consecutive writes, each write 32 bits, as described below: * The order of writing each of the Dwords is from lower to upper addresses. * No other DoorBell can be rung (or even start ringing) in the midst of an on-going write of a DoorBell over a given UAR page. The last rule implies that in a multi-threaded environment, the access to a UAR page (which can be accessible by all threads in the process) must be synchronized (for example, using a semaphore) unless an atomic write of 64 bits in a single bus operation is guaranteed. Such a synchronization is not required for when ringing DoorBells on different UAR pages. Signed-off-by: Moti Haimovsky <> Acked-by: Yongseok Koh <>
Diffstat (limited to 'doc/guides/nics/mlx5.rst')
1 files changed, 5 insertions, 1 deletions
diff --git a/doc/guides/nics/mlx5.rst b/doc/guides/nics/mlx5.rst
index 0d0d217..ebf2336 100644
--- a/doc/guides/nics/mlx5.rst
+++ b/doc/guides/nics/mlx5.rst
@@ -49,7 +49,7 @@ libibverbs.
-- Multi arch support: x86_64, POWER8, ARMv8.
+- Multi arch support: x86_64, POWER8, ARMv8, i686.
- Multiple TX and RX queues.
- Support for scattered TX and RX frames.
- IPv4, IPv6, TCPv4, TCPv6, UDPv4 and UDPv6 RSS on any number of queues.
@@ -489,6 +489,10 @@ RMDA Core with Linux Kernel
- Minimal kernel version : v4.14 or the most recent 4.14-rc (see `Linux installation documentation`_)
- Minimal rdma-core version: v15+ commit 0c5f5765213a ("Merge pull request #227 from yishaih/tm")
(see `RDMA Core installation documentation`_)
+- When building for i686 use:
+ - rdma-core version 18.0 or above built with 32bit support.
+ - Kernel version 4.14.41 or above.
.. _`Linux installation documentation`:
.. _`RDMA Core installation documentation`: