[External] : Re: [PATCH v2] net/mlx5: fallback to verbs for Tx memory allocation if devx unsupported

[Banoth Saikumar]

Oracle Confidential

Hi Dariusz,

I noticed that this patch was later reverted by:

> net/mlx5: revert fallback to Verbs Tx allocation

The revert mentions that on Windows, DevX CQ creation was failing due to
a different allocation fallback behavior.

Could you please clarify what specific behavior needs to be addressed
for Windows?

Should the original fallback be reworked to handle the Windows case,
or should the fallback be avoided entirely when running on Windows?

I would like to understand the expected behavior so I can work on a
correct fix.

Thanks,
Banoth Saikumar

Oracle Confidential
________________________________
From: Dariusz Sosnowski <dsosnowski at nvidia.com>
Sent: 13 July 2026 16:45
To: Banoth Saikumar <banoth.saikumar at oracle.com>
Cc: viacheslavo at nvidia.com <viacheslavo at nvidia.com>; bingz at nvidia.com <bingz at nvidia.com>; dev at dpdk.org <dev at dpdk.org>; stable at dpdk.org <stable at dpdk.org>
Subject: [External] : Re: [PATCH v2] net/mlx5: fallback to verbs for Tx memory allocation if devx unsupported

On Tue, Jun 30, 2026 at 03:53:11PM +0530, banoth.saikumar at oracle.com wrote:
> From: Banoth Saikumar <banoth.saikumar at oracle.com>
>
> Previously, the mlx5 PMD attempted to allocate consecutive Tx memory
> using DevX without checking whether the NIC actually supported DevX.
> This led to allocation failures on legacy or unsupported NICs.
>
> This patch adds a fallback mechanism: if DevX is not available, the PMD
> skips DevX-based allocation and allows the verbs path to handle memory
> allocation and registration. This improves compatibility with older
> NICs and ensures Tx queue setup proceeds correctly.
>
> Fixes: bbfab2eb2528 ("net/mlx5: allocate and release unique
> resources for Tx queues")
> Cc: stable at dpdk.org
>
> Signed-off-by: Banoth Saikumar <banoth.saikumar at oracle.com>

Acked-by: Dariusz Sosnowski <dsosnowski at nvidia.com>
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