Re: [dpdk-dev] [PATCH v2] net/mlx5: add support for 32bit systems

[Shahaf Shuler <shahafs@mellanox.com>]

Tuesday, July 3, 2018 12:00 AM, Yongseok Koh:
> Subject: Re: [dpdk-dev] [PATCH v2] net/mlx5: add support for 32bit systems
> 
> 
> > On Jul 2, 2018, at 4:11 AM, Moti Haimovsky <motih@mellanox.com> wrote:
> >
> > 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 <motih@mellanox.com>
> > ---
> Acked-by: Yongseok Koh <yskoh@mellanox.com>

Applied to next-net-mlx, thanks. 

> 
> Thanks