Hello @chillinwithscb
I will try to answer all your doubts.
1. Standalone Build vs. Yocto Build
Standalone build: Think of it as just building the Linux kernel (and maybe device trees) directly from the kernel source tree using make. Useful when you are doing kernel changes, debugging drivers, or do not want to rebuild an entire Yocto image for every change.
Yocto build: This is like a "Image factory" . Yocto builds the full rootfs, kernel, U-Boot in a structured way. Use this when you are building a full system image.
In a few words, use Yocto for producing the final image that you flash to your device. Use the standalone build when you are developing a driver, tweaking the kernel, or doing fast experiments or changes.
2. I ran standalone build, now what?
When you build the kernel on standalone, it gives to you the kernel image (Image or zImage), your device tree (.dtb) and modules that can be Custom or included into the kernel.
Then, you can install those on the boot partition directly in your SD card or using the UUU tool.
3. By default, U-Boot loads from first FAT partition, so what?
That’s only useful if your board is booting from SD card or eMMC with a FAT partition (often /dev/mmcblk0p1). U-Boot expects to find Image and .dtb files.
You will see something like this on the U-boot logs:
reading Image from mmc 0:1...
That means U-boot is loading the image from first FAT partition.
4. Users can copy images to this partition, how?
Yes, this is easy like:
If using the SD directly in Host:
$ sudo cp Image yourboard.dtb /media/you/boot/
In U-boot:
$ ums 0 mmc 0This will change the board to USB mass storage, and you can drag your files to the boot partition.
5. Flash to RAW address – huh?
This is for writing directly to flash offsets (not filesystems). Think of it as "writing straight into memory".
UUU helps to avoid this.
6. zImage vs Image vs Image.gz?
zImage: Compressed kernel. Don't use on i.MX8.
Image: Uncompressed kernel. This is what U-Boot on i.MX8 expects.
Image.gz: Gzipped kernel.
For i.MX8 use Image.
And yes, that kind of command if for SD cards. But again, you can avoid it using UUU tool.
7. Device trees? I thought there was one?
U-boot loads the device tree for the kernel, and you can change it before to boot, so, that is the reason you can to have many device trees.
You can refer to this community post to more information about how to flash device trees and Linux Images.
Also, that post can answer your question: "I thought UUU was for installing. How can I use UUU with the standalone build?".
8. Yocto vs Standalone – pick one or both?
Use both. Yocto for production, standalone for development.
9. bitbake linux-imx – what is that?
Yes, you usually source the environment (source setup-environment), then use:
$ bitbake imx-image-full
That tells bitbake to build the Linux kernel (recipe = imx-image-full).
MACHINE=yourboard selects the hardware configuration.
10. What new board? Which U-Boot tree?
This is referring to when you clone U-Boot and create a custom board definition (e.g., your own .h and .c files for board init). They suggest you copy from a similar reference board and start modifying.
Finally, we are working to improve our documentation and it can be read for beginners, advanced and experts users, but at this moment, our guides are all we have available to share with customers.
I hope this can helps to you.
Best regards,
Salas.
