[yocto] defconfig file (or fragment files) not used

[Bruce Ashfield]

On 03/28/2018 12:27 PM, Vincent Daanen wrote:
> Hi,
> 
> I want to add CAN driver support to the kernel. Here is the procedure I 
> followed:
> 
>  1. Generate a .config file
>  2. Copy it to meta-myWork/recipes-kernel/linux/files/defconfig
>  3. Update it: set at the end the config to enable CAN as follows
> 
> # CAN Bus
> 
> CONFIG_NET=y
> 
> CONFIG_CAN=y
> 
> CONFIG_CAN_RAW=y
> 
> CONFIG_CAN_BCM=y
> 
> CONFIG_CAN_GW=y
> 
> #
> 
> # CAN Device Drivers
> 
> #
> 
> CONFIG_CAN_VCAN=y
> 
> # CONFIG_CAN_SLCAN is not set
> 
> CONFIG_CAN_DEV=y
> 
> # CONFIG_CAN_CALC_BITTIMING is not set
> 
> # CONFIG_CAN_LEDS is not set
> 
> # CONFIG_CAN_SJA1000 is not set
> 
>  4. Update the linux-yocto_%.bbappend file as follows
> 
> SUMMARY = "Recipe to configure kernel as required"
> 
> LICENSE = "CLOSED"
> 
> inherit kernel-yocto
> 
> FILESEXTRAPATHS_prepend := "${THISDIR}/files:"
> 
> SRC_URI += file://defconfig
> 
>  5. Request rebuilt:
> 
> bitbake linux-yocto-rt -c cleansstate
> 
> bitbake -k linux-yocto-rt
> 
> Once the image started (with qemu), I check if the CAN is enabled (using 
> zcat /proc/config.gz | grep CAN) and I always get “CAN not set”

Do you have all of the CAN* Kconfig dependencies in your defconfig ?
If you don't, the kernel config subsystem will turn them off.

Also note that a 'defconfig' translates to a merge config run (yes,
even with just a defconfig) of 'allnoconfig', so that can also be
turning off dependencies if they were only valid via their default
and were not explicitly specified.

You can set KCONFIG_MODE="alldefconfig" in a linux-yocto bbappend to
change what mode merge-config uses.

Bruce


> 
> I also tried using fragment and I got the same result ☹
> 
> According the user manual, it seems to me I’m doing the right think!
> 
> Does someone know why my defconfig file is not taken into account ?
> 
> Thanks
> 
> Vincent
> 
> 
>