fesetenv() does not set the control word

[Frederic Goualard]

Environment:
Ubuntu 8.04.4 LTS
gcc version 4.2.4 (Ubuntu 4.2.4-1ubuntu4)
libc6 2.7-10ubuntu5

The following program should modify the FPU control word:
==============================================
#include <stdio.h>
#include <fenv.h>
#include <math.h>

int main(int argc, char *argv[])
{
  fenv_t fpuenv;
  fegetenv(&fpuenv);
  printf("Initial CW: %hx\n",fpuenv.__control_word);
  fpuenv.__control_word = (fpuenv.__control_word & 0xf0ff) | 0x0200;
  printf("Modified CW: %hx\n",fpuenv.__control_word);
  fesetenv(&fpuenv);
  fegetenv(&fpuenv);
  printf("Stored CW: %hx\n",fpuenv.__control_word);

  return 0;
}
==============================================
The output should be:
Initial CW: 37f
Modified CW: 27f
Stored CW: 27f

The output is:
Initial CW: 37f
Modified CW: 27f
Stored CW: 37f

which means that the FPU control word is not set by fesetenv().