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    <head>
      <base href="http://llvm.org/bugs/" />
    </head>
    <body><table border="1" cellspacing="0" cellpadding="8">
        <tr>
          <th>Bug ID</th>
          <td><a class="bz_bug_link 
          bz_status_NEW "
   title="NEW --- - -march=native doesn't work in virtualized environment"
   href="http://llvm.org/bugs/show_bug.cgi?id=19236">19236</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>-march=native doesn't work in virtualized environment
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>new-bugs
          </td>
        </tr>

        <tr>
          <th>Version</th>
          <td>trunk
          </td>
        </tr>

        <tr>
          <th>Hardware</th>
          <td>PC
          </td>
        </tr>

        <tr>
          <th>OS</th>
          <td>Linux
          </td>
        </tr>

        <tr>
          <th>Status</th>
          <td>NEW
          </td>
        </tr>

        <tr>
          <th>Severity</th>
          <td>normal
          </td>
        </tr>

        <tr>
          <th>Priority</th>
          <td>P
          </td>
        </tr>

        <tr>
          <th>Component</th>
          <td>new bugs
          </td>
        </tr>

        <tr>
          <th>Assignee</th>
          <td>unassignedbugs@nondot.org
          </td>
        </tr>

        <tr>
          <th>Reporter</th>
          <td>mikulas@artax.karlin.mff.cuni.cz
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>llvmbugs@cs.uiuc.edu
          </td>
        </tr>

        <tr>
          <th>Classification</th>
          <td>Unclassified
          </td>
        </tr></table>
      <p>
        <div>
        <pre>I have x86-64 Debian sid installed in kvm-qemu. I have 64-bit clang-3.5
installed from Debian repository.

When compiling a simple program with -march=native, clang fails.
$ cat hello.c
#include <stdio.h>

int main(void)
{
        printf("Hello World!\n");
        return 0;
}
$ clang -march=native hello.c
error: unknown target CPU 'athlon'

Apparently, there is some bug in processor detection, even if the system is
64-bit, clang detects a 32-bit "athlon" processor and subsequently fails,
because
the 64-bit target doesn't know this processor.

Note that kvm reports some features of the underlying CPU (the CPU is
istanbul-class Opteron) as not present in order to allow the program to be
migrated. This probably confuses clang, so that it clasifies the CPU as 32-bit
Athlon.</pre>
        </div>
      </p>
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