On Thu, Oct 22, 2020 at 10:46:18AM -0700, Radivoje Jovanovic wrote: > Hello, > I am creating empty 4GB ext4 partition on emmc with parted like this: > parted -s -a optimal /dev/emmcblk0 mkpart data ext4 1024 5120 > mkfs.ext4 /dev/mmcblk0p7 (this is the partition that was created in > the previous step) > > I do not mount this partition before I do dd of the emmc. > dd of the emmc is done like this: > dd if=/dev/emmcblk0 | gzip -c | dd of=./image.bin > > after this I write back the emmc with the same binary file: > dd if=./image.bin | gunzip -c | dd of=. /dev/emmcblk0 Is the root file system (or any file system mounted read/write) located on /dev/emmcblk0? You seem to imply that /dev/emmcblk0p7 was mounted read write, so that would appear to be the case. If so, that's a bad idea. Don't do that. It's not safe. > at the boot the kernel reports: > EXT4-fs (mmcblk0p7): warning: mounting fs with errors, running e2fsck > is recommended That's probably because of the fact that mmcblk0p7 was moounted read/write at the time when you tried to save and restore img.bin. *Never* mess with a block device containing a mounted file system like this. > Buffer I/O error on dev mmcblk0p7, logical block 0, lost sync page write > EXT4-fs (mmcblk0p7): I/O error while writing superblock That implies that an I/O error from the eMMC device. That's a hardware issue, *probably* not related to the fact that partition was not mounted, but rather by lousy hardware Quality Assurance along the way. If the hardware device is throwing I/O errors, you need to root cause that issue first before worrying about any file system complaints. Cheers, - Ted
