The default menuconfig options for the petalinux-initramfs-image is . The config option is packaged in the image.ub file and is also copied into the images/linux folder with ramdisk prefixed to the filename (for example, ramdisk.cpio.gz.u-boot), if the image specified in
the config option name contains the initramfs. This is a tiny-based rootfile system
search for the EXT partition in SD/eMMC that is used as a real time rootfs file
system irrespective of boot mode. If the init script in the tiny rootfs system does
not find any rootfs in real time, it lands up into the tiny-based rootfs with the
prompt '/#'. For example, if you are in the QSPI boot mode and you have flashed the
BOOT.BIN, boot.scr, and image.ub files,
it will boot up to tiny rootfs and search for the ext2/3/4 to mount and use it as
real rootfs.
The default prebuilt/built images are configured as mentioned above to facilitate the larger rootfs support in PetaLinux.