From: Arnd Bergmann <arnd@arndb.de>

Changing mlx5 to call ip6_dst_lookup() means it now fails to link
when IPv6 is a loadable module but ipsec support is built-in:

ipsec.c:(.text+0x1061): undefined reference to `ip6_dst_lookup'

Add a Kconfig dependency that removes avoids this configuration.

Fixes: e35d7da8dd9e ("net/mlx5e: Use ip6_dst_lookup instead of ipv6_dst_lookup_flow for MAC init")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/net/ethernet/mellanox/mlx5/core/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/Kconfig b/drivers/net/ethernet/mellanox/mlx5/core/Kconfig
index 9cf394c66939..c298efe93f97 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/Kconfig
+++ b/drivers/net/ethernet/mellanox/mlx5/core/Kconfig
@@ -154,6 +154,7 @@ config MLX5_EN_IPSEC
 	depends on MLX5_CORE_EN
 	depends on XFRM_OFFLOAD
 	depends on INET_ESP_OFFLOAD || INET6_ESP_OFFLOAD
+	depends on IPV6!=m || MLX5_CORE=m
 	help
 	  Build support for IPsec cryptography-offload acceleration in the NIC.
 
-- 
2.39.5

On 2/4/2026 9:00 PM, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> Changing mlx5 to call ip6_dst_lookup() means it now fails to link
> when IPv6 is a loadable module but ipsec support is built-in:
> 
> ipsec.c:(.text+0x1061): undefined reference to `ip6_dst_lookup'
> 
> Add a Kconfig dependency that removes avoids this configuration.
> 
> Fixes: e35d7da8dd9e ("net/mlx5e: Use ip6_dst_lookup instead of ipv6_dst_lookup_flow for MAC init")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
>   drivers/net/ethernet/mellanox/mlx5/core/Kconfig | 1 +
>   1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/Kconfig b/drivers/net/ethernet/mellanox/mlx5/core/Kconfig
> index 9cf394c66939..c298efe93f97 100644
> --- a/drivers/net/ethernet/mellanox/mlx5/core/Kconfig
> +++ b/drivers/net/ethernet/mellanox/mlx5/core/Kconfig
> @@ -154,6 +154,7 @@ config MLX5_EN_IPSEC
>   	depends on MLX5_CORE_EN
>   	depends on XFRM_OFFLOAD
>   	depends on INET_ESP_OFFLOAD || INET6_ESP_OFFLOAD
> +	depends on IPV6!=m || MLX5_CORE=m

Thanks for the fix.
I received a report for this same error here: 
https://lore.kernel.org/oe-kbuild-all/202512261850.P5Jp5BSz-lkp@intel.com/

We were about to send a fix ourselves, it is to simply add:
   depends on IPV6 || !IPV6
Is there a specific reason to prefer "depends on IPV6!=m || 
MLX5_CORE=m"? To me, the IPV6 || !IPV6 syntax seems a bit cleaner.

Thanks!
Jianbo

>   	help
>   	  Build support for IPsec cryptography-offload acceleration in the NIC.
>

On Fri, Feb 6, 2026, at 10:56, Jianbo Liu wrote:
> On 2/4/2026 9:00 PM, Arnd Bergmann wrote:
>> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/Kconfig b/drivers/net/ethernet/mellanox/mlx5/core/Kconfig
>> index 9cf394c66939..c298efe93f97 100644
>> --- a/drivers/net/ethernet/mellanox/mlx5/core/Kconfig
>> +++ b/drivers/net/ethernet/mellanox/mlx5/core/Kconfig
>> @@ -154,6 +154,7 @@ config MLX5_EN_IPSEC
>>   	depends on MLX5_CORE_EN
>>   	depends on XFRM_OFFLOAD
>>   	depends on INET_ESP_OFFLOAD || INET6_ESP_OFFLOAD
>> +	depends on IPV6!=m || MLX5_CORE=m
>
> Thanks for the fix.
> I received a report for this same error here: 
> https://lore.kernel.org/oe-kbuild-all/202512261850.P5Jp5BSz-lkp@intel.com/
>
> We were about to send a fix ourselves, it is to simply add:
>    depends on IPV6 || !IPV6
> Is there a specific reason to prefer "depends on IPV6!=m || 
> MLX5_CORE=m"? To me, the IPV6 || !IPV6 syntax seems a bit cleaner.

MLX5_EN_IPSEC needs the dependency, but this is a 'bool' symbols.

The "IPV6 || !IPV6" syntax only works on tristate symbols, so you'd
have to put it into CONFIG_MLX5_CORE itself, but MLX5_CORE does
not actually have the IPV6 dependency unless MLX5_EN_IPSEC is
enabled.

     Arnd

On 2/6/2026 6:00 PM, Arnd Bergmann wrote:
> On Fri, Feb 6, 2026, at 10:56, Jianbo Liu wrote:
>> On 2/4/2026 9:00 PM, Arnd Bergmann wrote:
>>> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/Kconfig b/drivers/net/ethernet/mellanox/mlx5/core/Kconfig
>>> index 9cf394c66939..c298efe93f97 100644
>>> --- a/drivers/net/ethernet/mellanox/mlx5/core/Kconfig
>>> +++ b/drivers/net/ethernet/mellanox/mlx5/core/Kconfig
>>> @@ -154,6 +154,7 @@ config MLX5_EN_IPSEC
>>>    	depends on MLX5_CORE_EN
>>>    	depends on XFRM_OFFLOAD
>>>    	depends on INET_ESP_OFFLOAD || INET6_ESP_OFFLOAD
>>> +	depends on IPV6!=m || MLX5_CORE=m
>>
>> Thanks for the fix.
>> I received a report for this same error here:
>> https://lore.kernel.org/oe-kbuild-all/202512261850.P5Jp5BSz-lkp@intel.com/
>>
>> We were about to send a fix ourselves, it is to simply add:
>>     depends on IPV6 || !IPV6
>> Is there a specific reason to prefer "depends on IPV6!=m ||
>> MLX5_CORE=m"? To me, the IPV6 || !IPV6 syntax seems a bit cleaner.
> 
> MLX5_EN_IPSEC needs the dependency, but this is a 'bool' symbols.
> 
> The "IPV6 || !IPV6" syntax only works on tristate symbols, so you'd
> have to put it into CONFIG_MLX5_CORE itself, but MLX5_CORE does
> not actually have the IPV6 dependency unless MLX5_EN_IPSEC is
> enabled.
> 

Right, I meant moving the dependency to CONFIG_MLX5_CORE.
Your patch restricts only MLX5_EN_IPSEC, which causes the link error, 
even if it silently disables IPsec in that specific config.

Acked-by: Jianbo Liu <jianbol@nvidia.com>

>       Arnd

This is an AI-generated review of your patch. The human sending this
email has considered the AI review valid, or at least plausible.

For local reproduction steps see https://netdev-ai.bots.linux.dev/ai-local.html
---
net/mlx5e: fix ip6_dst_lookup link failure

This commit adds a Kconfig dependency to prevent a link failure when IPv6
is a loadable module but mlx5 ipsec support is built-in.

Fixes: e35d7da8dd9e ("net/mlx5e: Use ip6_dst_lookup instead of ipv6_dst_lookup_flow for MAC init")

> Add a Kconfig dependency that removes avoids this configuration.

This isn't a bug, but "removes avoids" appears to be an editing artifact
where two verbs were left in place of one.
-- 
pw-bot: cr