question > new jffs2 partition

[gxk]

Does the kernel format erased flash, defined as partition?

 From the Uboot prompt i erase the space:
erase 0xa0000000 +2800000

Configured my kernel to have 3 partitions.
The 3rd is started at address 0xa0000000 with size 0x2800000.
This partition mounted at system boot:

mount -t jffs22 /dev/mtdblock/2 /mnt

and after simple make dir

mkdir -p /mnt/abcd

Now, when i start the system 1st time, it is taking more time to load
at the `mkdir'. All follow reboots go smooth.

It is look like mtd driver formats the partition. Can anybody confirm this?
When is it happen?

Thanks for help.