Flashing a rootfs > 4GB to the Coral dev eMMC yields a corrupted rootfs.
The u-boot version runing on the Coral dev board is U-Boot 2017.03.3 (Nov 08 2019 - 22:29:30 +0000)
I've tried flashing using the Google fastboot and uuu from (GitHub - NXPmicro/mfgtools: Freescale/NXP I.MX Chip image deploy tools. ).
Both yield a corrupted rootfs.
To reproduce this simply flash an image > 4GB to the rootfs partition.
FB: flash -raw2sparse rootfs rootfs_arm64.img
My assumption would be that somewhere an overflow occurs which overwrites the eMMC therefore corrupting the rootfs.
