Busybox Init

[Rajeev Bansal]

Hi All,

I could find the problem in my init script, actually I was using 
switchroot command to move from my old root to new root. But busybox 
gives switch_root in place of switchroot. So when I replaced the 
switchroot with switch_root command, I could see it was mounting the new 
root fs that is /dev/sda2 in my case. But after that it was giving me 
the Kernel panic. I don't know why it was behaving like that. Ideally 
kernel should go and execute /sbin/init. I am mentioning below my new 
init script.
#!/bin/nash

mount -t proc /proc /proc
setquiet
echo Mounting proc filesystem
echo Mounting sysfs filesystem
mount -t sysfs /sys /sys
echo Creating /dev
mount -o mode=0755 -t tmpfs /dev /dev
mkdir /dev/pts
mount -t devpts -o gid=5,mode=620 /dev/pts /dev/pts
mkdir /dev/shm
mkdir /dev/mapper
echo Creating initial device nodes
mknod /dev/null c 1 3
mknod /dev/zero c 1 5
mknod /dev/systty c 4 0
mknod /dev/tty c 5 0
mknod /dev/console c 5 1
mknod /dev/ptmx c 5 2
mknod /dev/rtc c 10 135
mknod /dev/tty0 c 4 0
mknod /dev/tty1 c 4 1
mknod /dev/tty2 c 4 2
mknod /dev/tty3 c 4 3
mknod /dev/tty4 c 4 4
mknod /dev/tty5 c 4 5
mknod /dev/tty6 c 4 6
mknod /dev/tty7 c 4 7
mknod /dev/tty8 c 4 8
mknod /dev/tty9 c 4 9
mknod /dev/tty10 c 4 10
mknod /dev/tty11 c 4 11
mknod /dev/tty12 c 4 12
mknod /dev/ttyS0 c 4 64
mknod /dev/ttyS1 c 4 65
mknod /dev/ttyS2 c 4 66
mknod /dev/ttyS3 c 4 67
echo Creating block device nodes.
mkblkdevs
echo "Loading usbcore.ko module"
insmod /lib/usbcore.ko
echo "Loading uhci-hcd.ko module"
insmod /lib/uhci-hcd.ko
echo "Loading ohci-hcd.ko module"
insmod /lib/ohci-hcd.ko
echo "Loading ehci-hcd.ko module"
insmod /lib/ehci-hcd.ko
mount -t usbfs /proc/bus/usb /proc/bus/usb
echo "Loading mbcache.ko module"
insmod /lib/mbcache.ko
echo "Loading jbd.ko module"
insmod /lib/jbd.ko
echo "Loading ext3.ko module"
insmod /lib/ext3.ko
echo "Loading scsi_mod.ko module"
insmod /lib/scsi_mod.ko
echo "Loading sd_mod.ko module"
insmod /lib/sd_mod.ko
echo "Loading sg.ko module"
insmod /lib/sg.ko
echo "Loading libata.ko module"
insmod /lib/libata.ko
echo "Loading ata_generic.ko module"
insmod /lib/ata_generic.ko
echo "Loading ata_piix.ko module"
insmod /lib/ata_piix.ko
echo Waiting for driver initialization.
stabilized --hash --interval 250 /proc/scsi/scsi
insmod /lib/scsi_wait_scan.ko
rmmod scsi_wait_scan
mkblkdevs
echo Creating root device.
mkrootdev -t ext3 -o defaults,ro sda2
echo Mounting root filesystem.
mount /sysroot
echo Switching to new root and running init.
switch_root /dev/sda2 /sbin/init   ------------------------> I tried 
switch_root with or without arguments also.
ls -l
echo Booting has failed.
sleep -1

Thanks
Rajeev Bansal.

Loïc Grenié wrote:
> 2007/12/5, Rajeev Bansal <rajeevb at intoto.com>:
>   
>> Hello Walter,
>>
>> Please see below mentioned text which I extracted from
>> "ramfs-rootfs-initramfs.txt"
>>
>> What is initramfs?
>>     
>
> [snip]
>
>   
>> So according to them , it's init responsibility to mount the real root
>> device, I think VI init works in that way, but not sure about the
>> busybox Init. Can anyone clarify me that?
>>     
>
>     In the initramfs system you have no real init, in the usual UNIX sense.
>   There is a program that does some initialization of the software, often
>   loads module and mount real root file system, and launch /sbin/init
>   of the real root filesystem. This are two conceptually different things,
>   which unfortunately share the same name. The "init" that is present
>   in BB is not the one to put on an initramfs. You should really try another
>   mailing-list, because this one is not the correct one.
>
>          Loïc Grenié
>
>
>   



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