Hello, @zhijie
Thanks for the post. May I know which version BSP you are working with? BSP43?
For the detail flow of running Yocto, there is not formal document from NXP, since Yocto is the 3rd software and only the tools for building AUTO BSPs for NXP, I suggest referencing the https://docs.yoctoproject.org/ for technical details of Yocto itself, roughly speaking, the Yocto could help to compile TFA, U-boot, Linux and basic libs/tools for driving the A53 of S32G products.
1. fsl-image-base.bb is the basic recipe for building the BSP.
2. It is not necessary to extract the fsl-image-auto-s32g399aevb3-20250209105410.rootfs.sdcard file, actually, it is used to be directly flashed to the SD card or eMMC, you may reference the chapter 4.1 of BSP UM for details.
It would create 2/3 partitions on your SD/eMMC because of the partition table embedded in the binary.
3. The .sdcard file you mentioned creates an image with all necessary partitions and loads the bootloader, kernel and rootfs to this image. Once flashed, the corresponding bootloader/rootfs/kernel/dts would be put into SD/eMMC, then the board could boot from SD/eMMC, the rootfs is located in the SD/eMMC and will be loaded to the DDR during the boot phase.
By default settings, the kernel that built from BSP could support ext4 file system, there would not be extra settings for supporting this feature.
BR
Chenyin
