Kernel configs not being applied

Technical Support
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1

After recently upgrading to 2.8 we are having troubles getting configuration fragments applied to the kernel.

We have a .bbappend file that adds a few patches and configuration fragments to the kernel build. The patches are being applied correctly, but the kernel configuration fragments do not seem to make it into the work/colibri_imx7…/linux-toradex/4.9…/build/.config file. The config fragments (.cfg files) are being copied into the build directory, however.

Is there something we’re missing? This used to work fine in 2.7.

The SRC_URI includes the statement “file://sc16is7xx.cfg”. While the fragment file (generated by doing a menuconfig, then diffconfig) contains these statements:

CONFIG_SERIAL_SC16IS7XX_CORE=y
CONFIG_SERIAL_SC16IS7XX=y
# CONFIG_SERIAL_SC16IS7XX_I2C is not set
CONFIG_SERIAL_SC16IS7XX_SPI=y
2

Kernel configuration fragments are not supported with our regular downstream vendor kennels. For applying custom configuration changes have a look e.g. here.

3

Thanks. I had come to the same conclusion after reviewing our old build setup. Because were were using a custom kernel, and linux-yocto, the configuration fragments were supported.

4

You are very welcome.

5

Any particular reason the Toradex builds don’t use the standard yocto config fragment scheme? Yocto is hard enough. Deviating from it only adds more confusion.

6

Any particular reason the Toradex builds don’t use the standard yocto config fragment scheme?

I would not exactly call this scheme standard. It is only supported when using a specific Yocto Project Linux kernel recipe which builds off a specific Linux kernel source tree. Unfortunately, in our case due to mainly SoC vendor proprietary graphics/multimedia stacks, we are more or less forced to use different downstream Linux kernel source trees. Getting that rather special Yocto Project config fragment scheme integrated into all such downstream Linux kernel source trees would be a huge effort.

Yocto is hard enough. Deviating from it only adds more confusion.

I don’t think we deviate per se. For reasons as explained above we just can’t easily use their special Linux kernel recipe having certain pros and cons.