I have a very simple udev rule at /etc/udev/rules.d/sdcard.rules:

KERNEL=="mmcblk1", SUBSYSTEM=="block", SYMLINK+="sdCARD"

Problem is the symlink is not created for me automatically at boot. I have many other rules and all them work just fine at boot (my symlinks are created).

However, if I run this then the symlink IS created:

udevadm test /block/mmcblk1

What could be going on here? Why isn't it created at boot? Could the device not be available yet? How could I find that out?

Update One

Output of udevadm:

 looking at device '/block/mmcblk1':
    ATTR{stat}=="       9        0       74        0        1        0        8        0        0        0        0"
    ATTR{inflight}=="       0        0"
  • What if you use last rule... something like: KERNEL=="mmcblk[0-9]", SYMLINK+="sdcard-%k", OPTIONS="last_rule" ? – don_crissti Apr 16 '15 at 18:16
  • @don_crissti Just tried it out, doesn't seem to make a difference... – dtmland Apr 16 '15 at 18:59

Rename the rules file to: /etc/udev/rules.d/99-sdcard.rules , possibly some rules are required to run before it.

  • Tested just now - didn't appear to make a difference. I am so stumped on this problem. – dtmland May 26 '15 at 19:46
  • @dtmland , Could I ask what hardware setup you are using? Could you post output of udevadm info --name=/block/mmcblk1 --attribute-walk? – user.dz May 26 '15 at 19:53
  • @dtmland, you run it with --attribute-walk I don't see any parent device. What's this hardware/embedded system ? – user.dz May 26 '15 at 20:11
  • 1
    Yes, I ran it with the walk attribute. I believe the mmcblk1 is the parent device? It's on unreleased SAMA5D3 based hardware. – dtmland May 26 '15 at 20:43
  • 2
    @dtmland , I think that block device is added too early before udevd can catch it. – user.dz May 26 '15 at 21:21

Check that

  1. the boot environment has udev enabled
  2. that the newly created udev rules are included in the Linux boot environment.

For example (#2) for Arch Linux requires $ mkinitpio -P to update the boot initramfs image.

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