On 25.10.2011 07:55, Renjun Qu wrote: > Hello everyone: > I am building a small embedded linux system right now. I > confused that why the default rootfs must has a "dev/console" node. I > have made a experiment as follow: > 1st, configure the kernel(2.6.32) to support the initramfs > and initrd, and set the source of the initramfs to a directory which > only has a "root" node. > 2nd, configure the kernel to support the root file system on > nfs, and rebuild the kernel. I have created all necessary files and > directories in the directory exported by the nfs server. > 3rd, set the appropriate boot parameter, and boot my kernel. > The result is, the kernel can successfully mount the root > file system, but the "/sbin/init" program can not print any > information to me. My "sbin/init" program is just a hello world > program which only print some greeting information.There is a > "dev/console" device node in the nfs exported directory. > But if i set the source of the initramfs to empty, and redo > my experiment from the 2nd step,everything will be ok. So, i think > there must be a “dev/console” node in the rootfs. The real root file > system already has a "dev/console" node, why default rootfs must have > a dev/console node. Please help me. > > Best regards, > > Ren jun Qu > -- > To unsubscribe from this list: send the line "unsubscribe initramfs" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html Your small initramfs should have something like this in sbin/init: mknod -m 0666 /dev/null c 1 3 mount -t proc -o nosuid,noexec,nodev proc /proc mount -t sysfs -o nosuid,noexec,nodev sysfs /sys ismounted() { while read a m a; do [ "$m" = "$1" ] && return 0 done < /proc/mounts return 1 } _opt="-o mode=0755,nosuid,exec"; _fs="-t devtmpfs" ismounted /dev && { _opt="$_opt,remount"; unset _fs; } if ! mount $_fs $_opt devtmpfs /dev >/dev/null 2>&1; then # if it failed (remount can't fail - no need to redo $_opt), fall back to # normal tmpfs mount -t tmpfs $_opt tmpfs /dev >/dev/null 2>&1 # Make some basic devices first, let udev handle the rest mknod -m 0666 /dev/null c 1 3 mknod -m 0666 /dev/ptmx c 5 2 mknod -m 0600 /dev/console c 5 1 mknod -m 0660 /dev/kmsg c 1 11 fi # prepare the /dev directory (note: newer udevd takes care of it automatically) [ ! -h /dev/fd ] && ln -s /proc/self/fd /dev/fd >/dev/null 2>&1 [ ! -h /dev/stdin ] && ln -s /proc/self/fd/0 /dev/stdin >/dev/null 2>&1 [ ! -h /dev/stdout ] && ln -s /proc/self/fd/1 /dev/stdout >/dev/null 2>&1 [ ! -h /dev/stderr ] && ln -s /proc/self/fd/2 /dev/stderr >/dev/null 2>&1 -- To unsubscribe from this list: send the line "unsubscribe initramfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
