I have several options to format the sd card, and it seems to me some of my sd cards are broken as well.
FAT,EXT-4, MBT, GUID, LBA - I am confused.
What is the correct set of options to format a sd card for use as /overlay FS on my Linkit Smart 7688 Target that has a limited RAM and can be extended by a sd card?
I do this to create the /overlay:
#mount /dev/mmcblk0p1 /mnt
#tar -C /overlay -cvf - . | tar -C /mnt -xf -
#block detect > /etc/config/fstab
Then, the configuration file gets modified to look like this:
option target '/overlay'
option enabled '1'
That should work, what issue are you experiencing exactly?
./upper[ 69.739107] EXT4-fs error (device mmcblk0p1): ext4_validate_block_bitmap:395: comm tar: bg 16: bad block bitmap checksum
I think it's because I didn't correctly format the sd card. I'm missing a description of requirements how a sd card is expected to be prepaired.
A description how to prepare a sd card maybe with fdisk would be great. Not like the ones found by googling where fdisk key presures are described, but a description what is required like: Format: FAT32, Master Boot Record table, or FAT32, GUID table with LBA or what ever makes sense...
Follow the instruction linked above, this is a tested and working method.
You can skip partitioning and simply format the entire disk.
That message does not look like a user error... I would say the card is broken, but then it would have complained when you formatted it and did the initial copy.