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If you are developing anything on embedded Linux you need a Rootfs to boot Linux. Rootfs has always been a issue for me. I need some help.
My target system is ARM, U-Boot Linux simple.

a) I have seen a rootfs.tar.gz file which is copied from SD card to say 0x60000000 and then a 

bootm 0x40000000 0x50000000 0x60000000

-Does U-Boot uncompresses the rootfs image?
-How does Linux know which type of rootfs it is?

b) If bootarg is passed as root=/dev/mmcblk1p1, how does Linux know which type of rootfs it is?

c) sudo qemu-debootstrap --arch=armel precise ./precise/ creates directories with bin and other entries. How do I create a tar.gz out of it?

sawdust
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  • like i said i dont know much abt it, kindly describe the diff –  Feb 17 '14 at 06:50
  • ok, then (b) in my q is rootfs and (a) is initramfs –  Feb 17 '14 at 07:11
  • **Correction:** that `bootm` command specifies a **ramdisk image**. An **initramfs** would use a `cpio` archive, not a `tar` archive. My bad. The reference documentation is [here](https://www.kernel.org/doc/Documentation/filesystems/ramfs-rootfs-initramfs.txt). Where did you read the instructions or example you mention in "question a"? – sawdust Feb 17 '14 at 07:28
  • Did I make an incorrect edit to your question? Are you developing for an ARM target on a PC host? Or are you actually developing natively **on** an ARM host? – sawdust Feb 17 '14 at 07:38

1 Answers1

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In bootm you are specifying the system to where it can take the image of kernel. Regarding filesystem, your filesystem reside in root=/dev/mmcblk1p1. So copy the rootfs.tar.gz file in mmc and extract that .gz in mmc.

Amit
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