it´s from git.freescale.com. In addition, there is a defconfig file added on SRC_URI.
There is a defconfig file for every board, on every Linux revision. Some defconfigs are shared for more than one board (for example, every mx6 board), and some Linux version are not compatible for some boards (for example, imx53 is only compatible with 2.6.35).
During a bitbake linux-imx, a temp folder will be created under build/tmp/armv7-imx6....../linux-imx, with code from git, patches and defconfig. Then bitbake takes that defconfig and configure the kernel, built it, and deploy it.
So, in order to change the kernel configuration (make menuconfig) you must replace your defconfig file from meta-fsl-arm/recipes-kernel/linux/linux-imx-3.0.35/mx6
How to change kernel configuration
Create the new defconfig
Copy it to meta-fsl-arm/recipes-kernel/linux/linux-imx-3.0.35/mx6 (or the right folder for your board/kernel)
$ bitbake -c cleansstate linux-imx
$ bitbake linux-imx (if you want only the kernel image)
$ bitbake fsl-image-gui (if you want to generate a complete image using the new kernel)
How to make menuconfig with yocto
$ bitbake -c menuconfig linux-imx
will generate a config file on tmp/work/imx6qsabresd-poky-linux-gnueabi/linux-imx/3.0.35-r33.10/git/.config
The complete step by step to change the kernel configuration
It´s not a simple task, I know. Yocto is not the best tool for use to develop and customize kernel during development stage. It is easier to use an external toolchain (bitbake meta-toolchain). Once the kernel development, or customization, is done, the changes can be integrated in the Yocto so it is managed for production use.
I like to have a copy of kernel source code cloned on my machine directly from git.freescale.com, then I can re-configure it, rebuild it, apply some patches, make changes, and build it manually - any way I want it. So, I only change kernel using yocto when I know the bug and I know how to fix it, and I have the patch. (and this is the way I like to work)
Although this is how to configure (and even patch) kernel (if you want to patch kernel, follow the example in the recipes)
If you face any error, please, let me know. I tested the steps and it worked, but I´m using an Ubuntu machine, not a virtual machine (and I´m not sure how -c menuconfig will act in a virtual machine).