[PATCH net-next] docs: netdev: refine netdevsim testing guidance

[PATCH net-next] docs: netdev: refine netdevsim testing guidance

[Jakub Kicinski]

The library to create tests for both NIC HW and netdevsim has existed
for almost a year. netdevsim-only tests we get increasingly feel like
a waste, we should try to write tests that work both on netdevsim and
real HW. Refine the guidance accordingly.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---
CC: corbet@lwn.net
CC: skhan@linuxfoundation.org
CC: workflows@vger.kernel.org
CC: linux-doc@vger.kernel.org
---
 Documentation/process/maintainer-netdev.rst | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/Documentation/process/maintainer-netdev.rst b/Documentation/process/maintainer-netdev.rst
index 6bce4507d5d3..3aa13bc2405d 100644
--- a/Documentation/process/maintainer-netdev.rst
+++ b/Documentation/process/maintainer-netdev.rst
@@ -479,8 +479,14 @@ netdevsim
 
 ``netdevsim`` is a test driver which can be used to exercise driver
 configuration APIs without requiring capable hardware.
-Mock-ups and tests based on ``netdevsim`` are strongly encouraged when
-adding new APIs, but ``netdevsim`` in itself is **not** considered
+Mock-ups and tests based on ``netdevsim`` are encouraged when
+adding new APIs with complex logic in the stack. The tests should
+be written so that they can run both against ``netdevsim`` and a real
+device (see ``tools/testing/selftests/drivers/net/README.rst``).
+``netdevsim``-only tests should focus on testing corner cases
+and failure paths in the core which are hard to exercise with a real driver.
+
+``netdevsim`` in itself is **not** considered
 a use case/user. You must also implement the new APIs in a real driver.
 
 We give no guarantees that ``netdevsim`` won't change in the future
-- 
2.53.0

Re: [PATCH net-next] docs: netdev: refine netdevsim testing guidance

[Simon Horman]

On Wed, Mar 04, 2026 at 07:16:46AM -0800, Jakub Kicinski wrote:
> The library to create tests for both NIC HW and netdevsim has existed
> for almost a year. netdevsim-only tests we get increasingly feel like
> a waste, we should try to write tests that work both on netdevsim and
> real HW. Refine the guidance accordingly.
> 
> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
> ---
> CC: corbet@lwn.net
> CC: skhan@linuxfoundation.org
> CC: workflows@vger.kernel.org
> CC: linux-doc@vger.kernel.org

Reviewed-by: Simon Horman <horms@kernel.org>

> ---
>  Documentation/process/maintainer-netdev.rst | 10 ++++++++--
>  1 file changed, 8 insertions(+), 2 deletions(-)
> 
> diff --git a/Documentation/process/maintainer-netdev.rst b/Documentation/process/maintainer-netdev.rst
> index 6bce4507d5d3..3aa13bc2405d 100644
> --- a/Documentation/process/maintainer-netdev.rst
> +++ b/Documentation/process/maintainer-netdev.rst
> @@ -479,8 +479,14 @@ netdevsim
>  
>  ``netdevsim`` is a test driver which can be used to exercise driver
>  configuration APIs without requiring capable hardware.
> -Mock-ups and tests based on ``netdevsim`` are strongly encouraged when
> -adding new APIs, but ``netdevsim`` in itself is **not** considered
> +Mock-ups and tests based on ``netdevsim`` are encouraged when
> +adding new APIs with complex logic in the stack. The tests should
> +be written so that they can run both against ``netdevsim`` and a real
> +device (see ``tools/testing/selftests/drivers/net/README.rst``).
> +``netdevsim``-only tests should focus on testing corner cases
> +and failure paths in the core which are hard to exercise with a real driver.
> +
> +``netdevsim`` in itself is **not** considered
>  a use case/user. You must also implement the new APIs in a real driver.

I don't know if it's desirable, but the line wrapping could
also be updated.

>  
>  We give no guarantees that ``netdevsim`` won't change in the future
> -- 
> 2.53.0
> 

Re: [PATCH net-next] docs: netdev: refine netdevsim testing guidance

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net-next.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Wed,  4 Mar 2026 07:16:46 -0800 you wrote:
> The library to create tests for both NIC HW and netdevsim has existed
> for almost a year. netdevsim-only tests we get increasingly feel like
> a waste, we should try to write tests that work both on netdevsim and
> real HW. Refine the guidance accordingly.
> 
> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
> 
> [...]

Here is the summary with links:
  - [net-next] docs: netdev: refine netdevsim testing guidance
    https://git.kernel.org/netdev/net-next/c/8e235bc43326

You are awesome, thank you!
-- 
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