> On Sep 4, 2016, at 1:25 PM, Stefan Agner <stefan@agner.ch> wrote:
> 
> The kernel does not automatically mount devtmpfs when using initramfs
> based booting (even when using CONFIG_DEVTMPFS_MOUNT). If the rootfs
> is built with USE_DEVFS=1 (which is the default), the system ends up
> with a completely empty /dev to begin with.
> 
> Busybox uses the first entry in inittab slightly different than
> other init systems:
> <id>: WARNING: This field has a non-traditional meaning for BusyBox init!
> 
> The id field is used by BusyBox init to specify the controlling tty for
> the specified process to run on.  The contents of this field are
> appended to "/dev/" and used as-is.
> 
> Since /dev/null is not there yet, Busybox throws errors instead of
> executing the commands, and hence never mounts devtmpfs:
> init started: BusyBox v1.24.1 (2016-09-04 11:53:14 PDT)
> can't open /dev/null: No such file or directory
> can't open /dev/null: No such file or directory
> can't open /dev/null: No such file or directory
> can't open /dev/null: No such file or directory
> can't open /dev/null: No such file or directory
> can't open /dev/null: No such file or directory
> can't open /dev/null: No such file or directory
> 
> Avoid this circular dependency by not specifing <id>. With that
> Busybox ends up using the stdio of the init process and executes
> the inittab just fine.

This looks good. Have you also tested it when using busybox/mdev as main
init system just not in initramfs

> 
> Signed-off-by: Stefan Agner <stefan@agner.ch>
> ---
> meta/recipes-core/busybox/files/inittab | 14 +++++++-------
> 1 file changed, 7 insertions(+), 7 deletions(-)
> 
> diff --git a/meta/recipes-core/busybox/files/inittab b/meta/recipes-core/busybox/files/inittab
> index bfec4a7..2bc831c 100644
> --- a/meta/recipes-core/busybox/files/inittab
> +++ b/meta/recipes-core/busybox/files/inittab
> @@ -1,13 +1,13 @@
> # This is run first except when booting in single-user mode.
> 
> # Startup the system
> -null::sysinit:/bin/mount -t proc proc /proc
> -null::sysinit:/bin/mount -t sysfs sysfs /sys
> -null::sysinit:/bin/mount -t devtmpfs devtmpfs /dev
> -null::sysinit:/bin/mount -o remount,rw /
> -null::sysinit:/bin/mkdir -p /dev/pts
> -null::sysinit:/bin/mount -t devpts devpts /dev/pts
> -null::sysinit:/bin/mount -a
> +::sysinit:/bin/mount -t proc proc /proc
> +::sysinit:/bin/mount -t sysfs sysfs /sys
> +::sysinit:/bin/mount -t devtmpfs devtmpfs /dev
> +::sysinit:/bin/mount -o remount,rw /
> +::sysinit:/bin/mkdir -p /dev/pts
> +::sysinit:/bin/mount -t devpts devpts /dev/pts
> +::sysinit:/bin/mount -a
> 
> ::sysinit:/etc/init.d/rcS
> 
> --
> 2.9.0
>