In message 9c1eb1b90803140101t79d577ddsa396573307b1ce21@mail.gmail.com you wrote:
I'm using dd to generate the u-boot+kernel+rootfs image. I executed command like.. dd if=rootfs.jffs2 of=kernel.img bs=1 seek=ROOTFS_OFFSET But dd is quite slow, generating a 64MB image spends about 5 minutes.
Hm... you must be on a very slow machine, then.
I have changed bs=1 to bs=1024 or bigger, but the outputted image size is wrong, too big.
Perhaps you forgot that "seek" is counting in units of "bs"; i.e. if you change from "bs=1" to "bs=1024" you also have to change from "seek=ROOTFS_OFFSET" to "seek=$(expr ROOTFS_OFFSET / 1024)"
dd manpage says that bs is the size of read/write one time. Doesn't it make dd faster?
Yes, it does.
How do make dd faster?
See above.
Best regards,
Wolfgang Denk