Missing header files in built yocto SDK

The yocto SDK for the angstrom-lxde-image I built is somehow missing some headers (linux/delay.h, linux/tty_driver.h, linux/tty_flip.h, linux/virtio.h). Any idea what I need to change in the recipes to get them? I need them to compile the RPMsg TTY Example ( imx_rpmsg_tty.c « rpmsg « drivers - linux-toradex.git - Linux kernel for Apalis and Colibri modules ).

It really should not be necessary to build the RPMsg TTY example kernel module separately. It is part of all our images and can be loaded by just using modprobe imx_rpmsg_tty as documented in the FreeRTOS on the Cortex-M4 of a Colibri iMX7 article.

If you wish to compile the kernel module manually, refer to the Build U-Boot and Linux Kernel from Source Code article. Note that link to the source files points to a rather outdated kernel version (3.14.52). Our current image uses the toradex_4.9-1.0.x-imx branch.

If you want to use the Yocto SDK to build kernel modules out of tree, you would have to add the kernel sources to the SDK, e.g. by using:

TOOLCHAIN_TARGET_TASK_append = " kernel-devsrc"

Well, the goal at the end is not to get that kernel module running. It is to have a setup to code / test our own kernel modules.

I’m currently doing that tutorial to disable some kernel drivers that use resources that we want to use on the M4. Thanks for the input with the branch.

The idea of RPmsg TTY module would be that you can create a user space application which makes use of /dev/ttyRPMSG. For most cases there shouldn’t be changes necessary in the driver itself.

If you want to change the driver, probably the easiest way is to clone the complete kernel source tree and commit changes to a local git repository…

That is probably an easier way to start. I thought you might have some yocto packages with a recipe / source code for each kernel module. I might take a look into these in the future. Thanks a lot for your answer.