how to modify run level in zed board

Hi Srinivas,

Are you using a RAM disk image?  If so are you modifying /etc/inittab within the image itself or from the filesystem that is loaded into RAM at runtime?

One of the most overlooked kernel boot parameters is the runlevel.  I tried this on my ZedBoard using the Xilinx 2014.2 linux release:

http://www.wiki.xilinx.com/Zynq+2014.2+Release

I took the devicetree.dtb provided for ZedBoard and used dtc to convert it back to device tree source format.  I then edited the kernel bootargs line to append the runlevel to the end (the default is 5 if the runtime is not specified at boot time) like this:

bootargs = "console=ttyPS0,115200 root=/dev/ram rw earlyprintk 1";

That 1 in bootargs will tell the kernel to override the default runlevel go to runlevel 1.

Then I used the dtc again to convert the device tree source into a binary format and boot the system with the updated devicetree.

Regards,

-Kevin

Hi kevin,

Thanks for your valuable suggestion. i tried as per instruction.but i am unable to enter filesystem. i am unable to move in booting process as shown below

Removing any system startup links for run-postinsts ...
  /etc/rcS.d/S99run-postinsts
INIT: Entering runlevel: 1
Unmounting remote filesystems...
INIT: no more processes left in this runlevel


can you give the suggestion. how to proceed for furhter step.


Thanks & Regards,
srinivas Rao

Hi Srinivas,

I guess there is some confusion in what exactly it is you are trying to accomplish.

The console message you see is telling you that you have reached runlevel 1 and that INIT has finished launching all of the processes it was instructed to.

Are you simply looking to boot the system in runlevel 1 or do you simply want to bypass the login prompt?

If you are looking to boot the system in runlevel one then it sounds like you have already done so.

If you are looking to bypass the login prompt for development purposes you will need to modify your RAM disk image.  I assume you already understand the negative security implications of bypassing the login prompt and you are not planning to release your image upon other unsuspecting users without ample warning. 

Not sure if this is the cleanest way to do this, but it works okay for me:

1) Create an autologin script /home/root/autologin.sh that getty can invoke at startup and add the following lines to it:

#!/bin/sh
exec /bin/login -f root

2) Make the autologin script executable:

chmod a+x autologin.sh

3) Modify your /etc/inittab file and comment out getty line (so that you can undo all this work later when you go to production) at the very end of the file like this:

#PS0:2345:respawn:/sbin/getty -L 115200 ttyPS0 vt100

4) Then add the following line to the end of /etc/inittab to force the login of root automatically:

PS0:2345:respawn:/sbin/getty -l /home/root/autologin.sh -n -L 115200 ttyPS0 vt100

If you are using the RAM disk image from one of the Xilinx Releases like I did, then you will find these instructions useful for modifying the contents of your RAM disk image:

http://microzed.org/content/how-modify-ramdisk-image-comes-release-145

http://www.wiki.xilinx.com/Build+and+Modify+a+Rootfs

If someone has a cleaner way of doing this, please educate the rest us.

Regards,

-Kevin

Hi kevin

Thanks for reply. I have understood your suggestions. i am looking for bypass the login prompt for development purpose. i have used petalinux 2014.2 version. i got a image.ub, zImage, system.dtb, BOOT.BIn and  rootfs.cpio for file system from petalinux. where exactly i got a problem is even i try to do changes in bootargs file system not access from sdcard or mtd3. its creating own virtual file system. i can't do any modification in that because when i reboot the board everything will be taken from default state only. i hope you can understand my intention.


METHOD - 1

//.................................filesystem from sdcard and kernel image from mtd2 (spi flash).........................................//

mmcbootargs=console=ttyPS0,115200 root=/dev/mmcblk0p2 rw rootfstype=ext4
mmcbootcmd=run mmcbootargs ; sf probe 0; sf read 0xfa0000 0x520000 0xa80000 && bootm 0xfa0000
run mmcbootcmd


METHOD - 2

//............................file system from mtd3 and kernel imagge from mtd2  (spiflash )..............................................

bootargs=console=ttyPS0,115200 root=/dev/mtd3 rw earlyprintk 5
qspiboot_test= run bootargs ; sf probe 0; sf read 0xfa0000 0x520000 0xa80000 && bootm 0xfa0000

run qspiboot_test

//..............................................................................................................

Hi Srinivas,

Okay, I think I see what you are doing.

What I am getting at is that you should be able to modify your RAM disk image (in your case it is the rootfs.cpio file) from your PetaLinux development machine.

Here are the steps that I used to unpack, modify, and repack one on my development system:

1)  Create a temporary folder to hold your root file system so that it can be unpacked in the next step:

mkdir tmp_mnt

2)  Unpack the cpio archive to the temporary folder:

cd tmp_mnt/
sudo cpio -i < ../rootfs.cpio

3)  Make the desired modifications to the root file system files (in this step I did my edits to tmp_mnt/etc/inittab and created the autologin.sh script in tmp_mnt/home/root/).

4)  Once the modifications are complete, repack the cpio archive (starting from the tmp_mnt/ working directory):

cd ..
rm rootfs.cpio
sh -c 'cd tmp_mnt/ && sudo find . | sudo cpio -H newc -o' > rootfs.cpio

Now copy the updated rootfs.cpio image to your SD card and boot ZedBoard, you should see the modifications to the root file system in place at this point.

The bottom line is that yes you are correct in that any changes you make to the file system while it is loaded into RAM on ZedBoard will not persist between reboots.  However, you should be able to modify that file system image on your development machine to suit your needs.

Regards,

-Kevin

Hi kevin,


i have done as per previous information.

root@pradeep-desktop:/home/pradeep~#mkdir rootfs
root@pradeep-desktop:~#cd rootfs/
root@pradeep-desktop:/home/pradeep/rootfs#

i copied rootfs.cpio gile in this folder

root@pradeep-desktop:/home/pradeep/rootfs~#cpio -i < rootfs.cpio

root@pradeep-desktop:/home/pradeep/rootfs~#vim /home/root/autologin.sh

#!/bin/sh
exec /bin/login -f root

root@pradeep-desktop:/home/pradeep/rootfs/home/root~#chmod a+x autologin.sh

Modified my /etc/inittab file

#PS0:2345:respawn:/sbin/getty -L 115200 ttyPS0 vt100
PS0:2345:respawn:/sbin/getty -l /home/root/autologin.sh -n -L 115200 ttyPS0 vt100

root@pradeep-desktop:/home/pradeep/rootfs~#rm rootfs.cpio

root@pradeep-desktop:/home/pradeep/rootfs~#cd ..
root@pradeep-desktop:/home/pradeep~#sh -c 'cd rootfs/ && sudo find . | sudo cpio -H newc -o' > rootfs.cpio


everything clear upto this


these are  mtd parititions

0x000000000000-0x000000500000 : "boot"
0x000000500000-0x000000520000 : "bootenv"
0x000000520000-0x000000fa0000 : "kernel"
0x000000fa0000-0x000002000000 : "spare"

//............................... mtd3 partition...........................................//

flash_eraseall -j /dev/mtd3
flashcp -v  rootfs.cpio /dev/mtd3

//.........................my uboot commands...............................................//

bootargs=console=ttyPS0,115200 root=/dev/mtd3 rw earlyprintk 5
qspiboot_test=sf probe 0 0; sf read 0xfa0000 0x520000 0xa80000 && sf read 0x2000000 0xfa0000 0x1060000 && bootm 0xfa0000 0x2000000

//..........i am getting like this ....................................//

U-Boot-PetaLinux> run qspiboot_test
SF: Detected S25FL256S_64K with page size 256 Bytes, erase size 64 KiB, total 32 MiB
SF: 11010048 bytes @ 0x520000 Read: OK
SF: 17170432 bytes @ 0xfa0000 Read: OK
## Loading kernel from FIT Image at 00fa0000 ...
   Using 'conf@1' configuration
   Trying 'kernel@1' kernel subimage
     Description:  PetaLinux Kernel
     Type:         Kernel Image
     Compression:  gzip compressed
     Data Start:   0x00fa00f0
     Data Size:    7150584 Bytes = 6.8 MiB
     Architecture: ARM
     OS:           Linux
     Load Address: 0x00008000
     Entry Point:  0x00008000
     Hash algo:    crc32
     Hash value:   5d7f745d
   Verifying Hash Integrity ... crc32+ OK
Wrong Ramdisk Image Format
Ramdisk image is corrupt or invalid
U-Boot-PetaLinux>


can you tell me  where i did the mistake.


Thanks & Regards,
srinivas Rao