[yocto] Support UBI u-boot

[JH]

Thanks Gabriele and Andy,

On 2/6/20, Gabriele Zampieri <gabbla.malist at gmail.com> wrote:
> Hi JH,
>
> have you tried what we suggested you in your last thread? More specifically
> adding your defconfig and tweaking it through menuconfig. and then specify
> the UBOOT_MACHINE.

Yes, as I posted in another thread, the MTD, UBI are all set in my
Linux kernel defconfig, I have also added UBOOT_CONFIG = "nand" in my
layer machine config.

What I missed is u-boot overlay, as you and Andy alluded. I added
UBOOT_CONFIG[nand] += "mx6ull_14x14_evk_nand_config", but strange
enough, that mx6ull_14x14_evk_nand_config, did not set CONFIG_CMD_UBI
in its config.

I think I need to add an appended recipes-bsp to my layer just like I
added the recipes-kernel to my layer to overwrite kernel defconfig, I
need to overwrite u-boot defconfig.

In kernel, to overwrite defconfig, I run bitbake -c menuconfig
virtual/kernel, how can I generate u-boot defconfig, to run bitbake -c
menuconfig u-boot?

Thank you.

Kind regards,

- jh