Mounting image fails unless it appears at "Devices" of Dolphin's side panel

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1

Update: Kernel 6.6.26-1 LTS has no problem. This problem has nothing to do with Dolphin. It’s just that you can use Dolphin to mitigate the problem.

dd if=/dev/zero of=a.img bs=1M count=100
mkfs.ext4 a.img
sudo mount a.img mp

mount returns exit code 32:

mount: .../mp: 
 /dev/loop0 already mounted or mount point busy.
       dmesg(1) may have more information after failed mount system call.

Right click a.img in Dolphin to open a menu and click “mount”:

image

After that click unmount symbol of the image in Dolphin’s side panel:

image

Then mount command will success:

$ sudo mount a.img mp
mount: /home/qiu/test/mp: WARNING: source write-protected, mounted read-only.

And if you right click a.img to open a menu and click unmount, a.img will disappear from side panel and mount command will fail again.

My system info:

  • Dolphin 23.08.5
  • Kernel 6.8.5-1
2

Unmounting is like unplugging the device (a hdd, for example).
You need to plug it in again.
In this case that means you need to find the file again and open/mount it.

After you unmount it, it is just a simple random file - why would it appear as a drive to mount?

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3

Never mind the image file’s content. It’s just an example. :grinning:

My question is that I cannot mount an image without Dolphin. sudo mount <img> <mount point> fails with exit code 32. I have to “plug” it in Dolphin at first. Is it a normal operation or a bug of Dolphin?

4

Your mount command may be syntactically incorrect - it can only work in certain cases:
sudo mount a.img mp

I get a different error message:
mount: mp: mount point does not exist.

Give it the path to the directory where you want to mount it.

If I create the directory mp and execute the command from the parent directory - it works.
mkdir mp
sudo mount a.img mp
in general:
sudo mount a.img /path_to_mountpoint

It will still disappear from “Devices” in Dolphin, once you unmount it.

Kernel 6.8 seems to have all kinds of strange issues - with snaps, for instance - which do use loop devices as well
Perhaps switch to a different one? (LTS)

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5

The dmesg is loop0: detected capacity change from 0 to ...
Seems it only fails on my PC, and has nothing to do with Dolphin. I’ll try reproducing it on another PC (or switch to another kernel version as you adviced) and figure out error message.
Thanks for your reply.

6

… half a message is of no use :slightly_smiling_face:

How about simply booting a different (possibly LTS) kernel?
Anyway: good luck!

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