[yocto] Deactivating KERNEL_FEATURES

[Bruce Ashfield]

On Tue, Jan 29, 2019 at 9:50 PM Chuck Wolber <chuckwolber at gmail.com> wrote:
>
> This question is with respect to the Yocto thud (2.6.x) branch. I have also reviewed section 2.3.3 and 2.3.4 of the Kernel Development document.
>
>
> My kernel configuration (cfg) seems to be overridden by KERNEL_FEATURES and it is not clear how to stop this behavior. To take one specific example, nothing I have tried seems to successfully deactivate the sound configuration kernel options.
>
> My linux-yocto_4.18.%.bbappend file has the following contents:
>
> FILESEXTRAPATHS_prepend := "${THISDIR}/files:"
> SRC_URI_append += "file://0001-kernel-config.cfg"
>
> The following line appears in 0001-kernel-config.cfg:
>
> # CONFIG_SOUND is not set
>
> And yet when I configure the kernel (bitbake -c configure linux-yocto) the resultant .config in the linux-yocto ${WORKDIR} contains "CONFIG_SOUND=m" and a plethora of other sound related options that should be turned off. I did the full kernel build and verified that the .config reflects the final result in the kernel.
>
> "bitbake -e linux-yocto" contains the following, which seems to explain a bit:
>
> KERNEL_FEATURES=" features/nfsd/nfsd-enable.scc features/debug/printk.scc  features/kernel-sample/kernel-sample.scc features/netfilter/netfilter.scc cfg/virtio.scc cfg/sound.scc cfg/paravirt_kvm.scc "
>
> I should also add that our configuration includes:
>
> DISTRO_FEATURES_remove = " alsa pulseaudio" DISTRO_FEATURES_BACKFILL_CONSIDERED = " alsa pulseaudio".
>
>
> How do I ensure that my kernel config gets the last say and is not overridden?

KERNEL_FEATURES is a variable like any other. Have you tried using
KERNEL_FEATURES_remove to pull the sound configs out ? We've also only
enabled those features for the qemux86* machines, so it shouldn't be
leaking into other configs .. but as you mentioned, perhaps the sound
configs are just something you picked as an example.

Bruce

>
> Thank you,
>
> ..Ch:W..
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