Re: [PATCH v2] ipv6: default IPV6_SIT to m

[Fernando Fernandez Mancera <fmancera@suse.de>]

On 5/3/26 9:25 PM, Alyssa Ross wrote:
> This basically defaulted to m until recently, since IPV6 defaulted to
> m.  Since IPV6 was changed to a boolean with a default of y, IPV6_SIT
> started defaulting to built-in as well.  This results in a surprise
> sit0 device by default for defconfig (and defconfig-derived config)
> users at boot.  For me, this broke an (admittedly non-robust) script.
> Preserve the behaviour of most configs by avoiding building this
> module, that's probably overall seldom used compared to IPv6 as a
> whole, into the kernel.
> 
> Fixes: 309b905deee59 ("ipv6: convert CONFIG_IPV6 to built-in only and clean up Kconfigs")
> Signed-off-by: Alyssa Ross <hi@alyssa.is>

Hi, I am not sure about this. IPV6_SIT was already defaulting to 'y' for 
most distributions (except for ARM). Sure, if you had CONFIG_IPV6=m then 
CONFIG_IPV6_SIT was defaulting to 'm'.

Hm. Maybe we can aim this for net-next tree instead of net? I just don't 
think this is a fix but a change in behavior. FWIW, it makes sense to me 
to have this as a module by default.

Let's see what do others think.

Please respect the 24 hours period before reposting

https://docs.kernel.org/process/maintainer-netdev.html#resending-after-review

Thanks,
Fernando.

> ---
> v2: update help text as well
> 
>   net/ipv6/Kconfig | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/net/ipv6/Kconfig b/net/ipv6/Kconfig
> index c024aa77f25ba..c3806c6ac96f9 100644
> --- a/net/ipv6/Kconfig
> +++ b/net/ipv6/Kconfig
> @@ -164,7 +164,7 @@ config IPV6_SIT
>   	select INET_TUNNEL
>   	select NET_IP_TUNNEL
>   	select IPV6_NDISC_NODETYPE
> -	default y
> +	default m
>   	help
>   	  Tunneling means encapsulating data of one protocol type within
>   	  another protocol and sending it over a channel that understands the
> @@ -172,7 +172,7 @@ config IPV6_SIT
>   	  into IPv4 packets. This is useful if you want to connect two IPv6
>   	  networks over an IPv4-only path.
>   
> -	  Saying M here will produce a module called sit. If unsure, say Y.
> +	  Saying M here will produce a module called sit. If unsure, say M.
>   
>   config IPV6_SIT_6RD
>   	bool "IPv6: IPv6 Rapid Deployment (6RD)"
> 
> base-commit: 254f49634ee16a731174d2ae34bc50bd5f45e731