[linux-yocto] linux-yocto-rt_3.4, dora: cannot override KERNEL_FEATURES_append

[Bruce Ashfield]

On 15-08-19 11:12 AM, Cristian Bercaru wrote:
> Hello!
>
> I want to compile a 3.4 preempt linux kernel on dora, without netfilter
> and taskstats support.
>
> I see that these features are added in
> meta/recipes-kernel/linux/linux-yocto-rt_3.4.bb
>    KERNEL_FEATURES_append = " features/netfilter/netfilter.scc"
>    KERNEL_FEATURES_append = " features/taskstats/taskstats.scc"
>
> In my .bbappend I tried overriding the variable
>    KERNEL_FEATURES_append = ""

The _append isn't going to zero out the KERNEL_FEATURES, so the
netfilter features are still going to be applied.

> but nothing happens. I still get netfilter options in my final .config:
>    CONFIG_NETFILTER=y
>    CONFIG_NETFILTER_ADVANCED=y
>    ...
> although I use a defconfig with these features disabled
>    # CONFIG_NETFILTER is not set

kernel features are applied after all defconfigs, fragments, etc, are
processed, so the fact that you aren't really removing it .. means
that they'll come back in the final .config.

>    ...
>
> How can I get rid of netfilter in my .config? The only solution that
> worked was modifying meta/recipes-kernel/linux/linux-yocto-rt_3.4.bb,
> but that is outside the scope of my meta-axxia layer.

In newer variants of the recipes, I did this:

KERNEL_EXTRA_FEATURES ?= "features/netfilter/netfilter.scc" 
 
 


So dependent layers could easily disable netfilter. I suppose that isn't
in the variant you are using ?

Otherwise, we need to clobber KERNEL_FEATURES using another type of
override in your layers .. and these are normal bitbake variables, so
normal rules apply.

I'd have to experiment to get the right syntax, since I'm only marginally
a better variable wizard than the next person.

Bruce



>
> Thanks,
> Cristian Bercaru