can not create /dev/shm

Question

I need to create /dev/shm on an embedded ARM system. From "Installed The Latest Changes to Current and......".

I see that it can be created with mkdir /lib/udev/devices/shm, but I'm wondering what is supposed to be at that location? The only directory I have at that location is /lib/modules/, there's no devices/ or anything.

So I went ahead and just created them, empty directories. I then added:

tmpfs                   /dev/shm                tmpfs   defaults       0 0

to my /etc/fstab and I didn't add an mtab entry, since I don't have an /etc/mtab. I then rebooted and now, there's still no /dev/shm device.

Any ideas how I get that device?

EDIT #1

Oh, and a mount -a (after a reboot) results in:

# mount -a
mount: mounting tmpfs on /dev/shm failed: No such file or directory`

Solution

An embedded system may have a static /dev, rather than use udev to populate it. If you don't have /lib/udev, then presumably your system isn't running udev. In that case, you need to create /dev/shm on the root filesystem.

If the root filesystem is an initramfs, rebuild your initramfs with an extra line in the initramfs description file:

dir /dev 755 0 0
dir /dev/shm 755 0 0
…

If the root filesystem is an on-disk filesystem, just create the directory.

# mkdir /dev/shm

Comments

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