udev: only use devtmpfs for udev
Fix for bug: https://bugzilla.yoctoproject.org/show_bug.cgi?id=4632
Since udev 172, the 'mknod' logic was removed from udev. Yocto Dylan
is now using udev 182. This means /dev is now required to be a
devtmpfs filesystem (maintained by the kernel). If the root
filesystem is a ramdisk, the kernel's auto-mount of /dev doesn't
activate since there is no rootfs to actually mount... The bug causes
an unusable system as /dev doesn't contain even basic nodes required
to even get a login prompt.
The Yocto udev/init script mounts tmpfs if it does not detect tmpfs
or devtmpfs mounted at /dev. This appears to be outdated logic that
is no longer correct. I believe the Yocto udev init script should be
checking and mounting only 'devtmpfs' on dev.
(From OE-Core master rev:
31ab19ab69bc6504df01cac7ee0670ca78d247ab)
Signed-off-by: Alex Olson <alex.olson+yocto@gmail.com>
[YOCTO #4632]
Signed-off-by: Saul Wold <sgw@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
