[Buildroot] mdev problem in 2011.08 ?

Thomas Petazzoni thomas.petazzoni at free-electrons.com
Sun Sep 18 14:28:42 UTC 2011

Hello Pierre,

Le Sun, 18 Sep 2011 15:01:51 +0200,
Pierre Ficheux <pierre.ficheux at openwide.fr> a écrit :

> May be I'm wrong but it seems there is a problem when using mdev for
> /dev management:

For our mdev and udev support, we assume that the kernel is compiled
with CONFIG_DEVTMPFS and CONFIG_DEVTMPFS_MOUNT. For kernels built by
Buildroot, this is ensured by :

                $(call KCONFIG_ENABLE_OPT,CONFIG_DEVTMPFS,$(@D)/.config)
                $(call KCONFIG_ENABLE_OPT,CONFIG_DEVTMPFS_MOUNT,$(@D)/.config))

in linux/linux.mk.

For kernels built outside of Buildroot, it's up to the user to enable
those options. In your case, I guess your kernel lacks devtmpfs support
and/or the option to have devtmpfs mounted automatically at boot time,
and this explains why the /dev/null device is missing.


Thomas Petazzoni, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.

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