Preparing a ramdisk

From iPhone Linux

The following instructions modify a buildroot filesystem to use mdev/gadget serial.

As a reminder, you probably want to select the lrzsz package from the network packages in buildroot menuconfig when you build it. This will allow file transfer via kermit later on.

Modifying /dev

Remove all files from /dev/ except /dev/console and /dev/null, e.g. by performing an rm -rf, and then adding back /dev/console and /dev/null:

 mknod /mnt/dev/console c 5 1
 mknod /mnt/dev/null c 1 3
 chmod a+w /mnt/dev/console
 chmod a+w /mnt/dev/null

Modifying /etc/inittab

Add the following lines to /etc/inittab, after null::sysinit:/bin/mount -a. These steps sets up /dev and starts mdev (BusyBox's version of udev).

 null::sysinit:/bin/mount -t tmpfs -o size=64k,mode=0755 tmpfs /dev
 ::sysinit:/bin/mknod /dev/null c 1 3
 null::sysinit:/bin/mkdir /dev/pts
 null::sysinit:/bin/mount -t devpts devpts /dev/pts
 null::sysinit:/sbin/sysctl -w kernel.hotplug=/sbin/mdev
 null::sysinit:/sbin/mdev -s

Add the following line after # Put a getty on the serial port

 ttyGS0::respawn:/sbin/getty -L ttyGS0 9600 vt100

Modifying /etc/securetty

Add ttyGS0 to the list.