Yocto Build Linux from source code

It is recommended to build the kernel image using Yocto (see the Customizing the Linux kernel and U-Boot page) instead of using the direct method described in this page.
This is because some of the Yocto packages depends on the kernel, like the WiFi module that is built from outside of the kernel source tree.

Toolchain installation for out of Yocto builds

To install the toolchain, follow Yocto Toolchain installation.

Build Linux out of Yocto tree

Get the Linux source code:

$ git clone https://github.com/varigit/linux-2.6-imx.git
$ cd linux-2.6-imx
$ git checkout imx-rel_imx_4.1.15_2.0.0_ga-var02

Build the Linux kernel:

$ source /opt/fslc-x11/2.2.1/environment-setup-armv7at2hf-neon-fslc-linux-gnueabi

$ make mrproper
$ make imx6ul-var-dart_defconfig

Build everything:
$ make -j4

Build zImage only:
$ make -j4  zImage

Build modules only:
$ make -j4  modules

Build device trees only:
$ make -j4 dtbs

Build only the device tree for DART-6UL with i.MX6UL SOC, eMMC and WiFi:
$ make -j4 imx6ul-var-dart-emmc_wifi.dtb

Build only the device tree for DART-6UL with i.MX6UL SOC, eMMC and SD card:
$ make -j4 imx6ul-var-dart-sd_emmc.dtb

Build only the device tree for DART-6UL with i.MX6UL SOC, NAND flash and WiFi:
$ make -j4 imx6ul-var-dart-nand_wifi.dtb

Build only the device tree for DART-6UL with i.MX6UL SOC, NAND flash and SD card:
$ make -j4 imx6ul-var-dart-sd_nand.dtb

Build only the device tree for DART-6UL with i.MX6ULL SOC, eMMC and WiFi:
$ make -j4 imx6ull-var-dart-emmc_wifi.dtb

Build only the device tree for DART-6UL with i.MX6ULL SOC, eMMC and SD card:
$ make -j4 imx6ull-var-dart-sd_emmc.dtb

Build only the device tree for DART-6UL with i.MX6ULL SOC, NAND flash and WiFi:
$ make -j4 imx6ull-var-dart-nand_wifi.dtb

Build only the device tree for DART-6UL with i.MX6ULL SOC, NAND flash and SD card:
$ make -j4 imx6ull-var-dart-sd_nand.dtb

Notes:

If you replace the kernel image (zImage) on your system, you also need to reinstall the kernel modules, and vice versa.

If you just want to make a change in the device tree, you can compile and replace it without replacing the kernel image and modules.

Install the built kernel on an SD card

Copy the zImage and device trees to the SD card boot partition, and install the modules in the SD card rootfs partition.
Assuming the boot partition is mounted on /media/user/BOOT-DART-6UL and the rootfs partition is mounted on /media/user/rootfs:

Install the kernel image and modules:
$ cp arch/arm/boot/zImage /media/user/BOOT-VAR6UL
$ sudo make ARCH=arm modules_install INSTALL_MOD_PATH=/media/user/rootfs

Install the device trees:
$ cp arch/arm/boot/dts/*var*.dtb /media/user/BOOT-VAR6UL

Note:
If you are using our Yocto Recovery SD card, and you want the NAND flash/eMMC installation to update as well as the SD card boot itself, you need to also update the /opt/images/Yocto directory.