[WireGuard] [LEDE-DEV] Kernel symbol dependencies and KCONFIG usage for kernel packages

[Baptiste Jonglez]

On Sat, Jul 02, 2016 at 03:48:36PM +0200, Hauke Mehrtens wrote:
> > However, I have some trouble understanding what KCONFIG does.  Wireguard
> > needs a few kernel options, so I thought that KCONFIG was the place to
> > declare such dependencies:
> > 
> >   https://github.com/zorun/packages-1/blob/wireguard/net/wireguard/Makefile#L90
> 
> > KCONFIG:=CONFIG_NET_UDP_TUNNEL CONFIG_IPV6 \
> >          CONFIG_NETFILTER_XT_MATCH_HASHLIMIT
> 
> Instead of activating the kernel symbols you should add a dependency to
> the packages which are building these models:
> 
> DEPENDS:=+kmod-udptunnel4 +kmod-udptunnel6 +kmod-ipt-hashlimit

Well, actually, this is already there, on the next line :)

  https://github.com/zorun/packages-1/blob/wireguard/net/wireguard/Makefile#L91

So, I can remove the KCONFIG line altogether?  I thought the kernel
symbols activated some necessary machinery in the kernel, in addition to
producing the .ko module.

I think I found the cause of the issue: the packages kmod-udptunnel4.ipk
and kmod-udptunnel6.ipk are generated, but are empty (no .ko file).  When
I activate the kernel symbol in kernel_menuconfig, these packages do
provide the .ko files as expected.

I have attached the empty packages to this email, just in case.

Thanks,
Baptiste
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