7

I saw this command to make image

qemu-system-arm -kernel kernel-qemu -cpu arm1176 -m 256 -M versatilepb \
-no-reboot -serial stdio -append "root=/dev/sda2 panic=1" \
-hda 2013-05-25-wheezy-raspbian.img

Here the -append field gives me some doubt...

It says /dev/sda2: does it refer to my own disk (/dev/sda2) ?

On manual page it says:

-append cmdline

Use cmdline as kernel command line

I'm confused here.

closed as off-topic by lenik, syb0rg, Impulss, nc4pk, hifkanotiks Oct 20 '13 at 13:58

This question appears to be off-topic. The users who voted to close gave this specific reason:

  • "Questions on Linux use unrelated to the RaspberryPi are off-topic here, but can be asked on Unix & Linux Stack Exchange." – lenik, syb0rg, Impulss, nc4pk
If this question can be reworded to fit the rules in the help center, please edit the question.

3

The append line adds extra options to the kernel command line in UNIX derivatives. You can add many extra options such as

  • root device (/dev/sda2 in your example)
  • initrd file
  • debugging options such as 'quiet'
  • hdd emaulation (ide-scsi)
  • boot type (single, rescue etc.)
  • VGA mode

You can find which options you can pass to append line in QEMU kernel options manual : page is now archived

Edit:

If you want to pass different root partition you can pass via root=/dev/sdXX. You should display your disk layout with fdisk command if you don't know your image's root partition. Example of a sd card image disk layout:

root@pi# fdisk -l moebius.1.0.1.img 

Disk moebius.1.0.1.img: 943 MB, 943718400 bytes
255 heads, 63 sectors/track, 114 cylinders, total 1843200 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x000714e9

            Device Boot      Start         End      Blocks   Id  System
moebius.1.0.1.img1            8192      122879       57344    c  W95 FAT32 (LBA)
moebius.1.0.1.img2          122880     1761279      819200   83  Linux

As you can see linux root partition is 2nd partition, that means it will named /dev/sda2 when you try to boot via qemu-system-arm.

  • thnks.....i thought /dev/sda2 will mess up with my disk /dev/sda2 but, i just did it....and it worked for me..... – murarisumit Sep 10 '13 at 7:36
  • if you can help me....who actually made: /dev/sda2 i just used the image and tutorial...was partition made in the image have i used to build it ....??? – murarisumit Sep 10 '13 at 7:37

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