<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/136491>136491</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            Runtime unavailability of unified shared memory not disclosed by libomptarget
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            new issue
      </td>
    </tr>

    <tr>
      <th>Assignees</th>
      <td>
      </td>
    </tr>

    <tr>
      <th>Reporter</th>
      <td>
          KaruroChori
      </td>
    </tr>
</table>

<pre>
    > I found the issue at least in my case. Debian official kernel images are built without CONFIG_DEVICE_PRIVATE.  
> Which is needed for this feature to work.
> https://forums.developer.nvidia.com/t/how-to-enable-hmm-on-debian/316561
> 
> Time to rebuild the kernel.
> 
> **Addendum**: I can confirm that with the freshly baked kernel it works. 

 _Originally posted by @KaruroChori in [#127334](https://github.com/llvm/llvm-project/issues/127334#issuecomment-2817171884)_

Debian's kernel images, and possibly others, don't ship with support for USM out of the box.  
At runtime, applications which have been built with `#pragma omp requires unified_shared_memory` are going to fail without providing any meaningful error message which describes the issue.  
It would be nice if libomptarget could perform a check at runtime and provide a more meaningful error message for this type of failure.
</pre>
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