xenomai shared memory causes mode switches

gistfile1.c

#include <sys/mman.h>
#include <sys/stat.h>        /* For mode constants */
#include <fcntl.h>           /* For O_* constants */
#include <stdio.h>
#include <error.h>
#include <errno.h>
#include <native/task.h>

#define SHM_NAME "/myshared"

int main ()
{
    rt_print_auto_init(1); // enable rt_printf output
    // turn ourselves into a xenomai task, in primary mode
    rt_task_shadow(NULL, "main", 95, T_FPU);    
    int fd;
    int count = 0;
    // this will switch us to secondary mode
    //chose either line according to your kernel config
    fd = shm_open(SHM_NAME, O_RDWR | O_CREAT | O_DIRECT, 0); // CONFIG_XENO_OPT_POSIX_SHM=y
    //fd = shm_open(SHM_NAME, O_RDWR | O_CREAT, 0); // CONFIG_XENO_OPT_POSIX_SHM=n
    if(fd < 0){
        printf("%s\n", strerror(errno));
        return 1;
    }

    rt_printf("Opened\n");
    size_t len = 40;
    ftruncate(fd, len);
    rt_printf("size: %d\n", len);
    void* ignored;
    //this causes a switch to secondary mode
    void* addr = mmap(ignored, len, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
    if(addr == MAP_FAILED){
        rt_printf("Error: %s %p\n", strerror(errno));
        return 1;
    }
    rt_printf("mmapped\n");
    float* arr = (float*)addr;

    // can now force to go back to primary mode
    rt_task_shadow(NULL, "main", 95, T_FPU);

    unsigned int n = 0;
    unsigned int j = 0;
    rt_printf("accessing mapped memory\n");
    for(j = 0; j < 10; ++j){
        for(n = 0; n < len/sizeof(float); ++n){
            // from here we should be able to access memory without mode switches
            // so if this line causes mode switches, you would
            // see them incrementing
            arr[n] = (float)n;
            rt_task_sleep(0);  // sleep, switches to primary mode
            rt_printf("%f\n", arr[n]);
            rt_task_sleep(0);  // sleep, switches to primary mode
        }
        rt_task_sleep(900000000);  // sleep, switches to primary mode
    }
    rt_task_sleep(5000000000); //sleep 5 seconds so you can have a final look at /proc/xenomai/stat
    close(fd);
    return 0;
}