Re: [PATCH] cfg80211: remove net-pf-16-proto-16-family-nl80211 module alias

[Dan Williams <dcbw@redhat.com>]

On Thu, 2014-11-13 at 22:48 +0900, Marcel Holtmann wrote:
> Hi Stanislaw,
> 
> >>> With the alias cfg80211 module is loaded on systems without the wireless
> >>> hardware when user-space use nl80211 to discover if there are wireless
> >>> devices, what is considered as resources wastage. On systems with
> >>> wireless hardware cfg80211 module will be loaded anyway.
> >>> 
> >>> Cc: Marcel Holtmann <marcel@holtmann.org>
> >>> Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
> >>> ---
> >>> net/wireless/core.c | 1 -
> >>> 1 file changed, 1 deletion(-)
> >>> 
> >>> diff --git a/net/wireless/core.c b/net/wireless/core.c
> >>> index a4d2792..badcabe 100644
> >>> --- a/net/wireless/core.c
> >>> +++ b/net/wireless/core.c
> >>> @@ -34,7 +34,6 @@
> >>> MODULE_AUTHOR("Johannes Berg");
> >>> MODULE_LICENSE("GPL");
> >>> MODULE_DESCRIPTION("wireless configuration support");
> >>> -MODULE_ALIAS_GENL_FAMILY(NL80211_GENL_NAME);
> >> 
> >> NAK.
> >> 
> >> We want to auto-load cfg80211 when userspace asked for nl80211 netlink family.
> > 
> > Could you elaborate more why?
> 
> you want to talk to the nl80211 family. The kernel has a module that allows you to talk to this family. So let it load the netlink family.
> 
> If you do not want cfg80211 loaded, then fix NetworkManager and not hack the kernel. NetworkManager asks to talk to nl80211 in the first place. That one is causing the loading of cfg80211 module.

Unfortunately there seems to be no reliable way of detecting that an
ethernet-type interface is WiFi (and talks nl80211) or is not WiFi, than
by asking it, using nl80211.  Unless you have suggestions for this?

Dan