no mmu problem

Please check the mmap call in your code. This is what used in microwin scr_fb.c,

<div class='quotetop'>QUOTE (hippo @ Aug 26 2009, 10:17 PM) <{post_snapback}> (index.php?act=findpost&pid=23617)</div>

int open_fb(void)
{
    fb_fp = open("/dev/fb0", O_RDWR);
    if(fb_fp <= 0)
    {
        printf("cannot open /dev/fb0\n");
        return -1;
    }
    return fb_fp;
}
int set_fb(void)
{
    //usleep(100000);    // Wait 100 ms
    printf("%s Start: %d \n", __FUNCTION__, __LINE__);
    //usleep(10000);    // Wait 10 ms
    struct fb_var_screeninfo fb_var;
    struct fb_fix_screeninfo fb_fix;
    if(ioctl(fb_fp, FBIOGET_FSCREENINFO, &fb_fix) == -1 ||
        ioctl(fb_fp, FBIOGET_VSCREENINFO, &fb_var) == -1) {
            printf("%s fbcon engine: Error when reading screen info: %d.\n", __FUNCTION__, __LINE__);
            return -1;
    } 
    usleep(100000);    // Wait 100 ms
    printf("%s Continue: %d \n", __FUNCTION__, __LINE__);
    usleep(100000);    // Wait 100 ms
    color_bits = (fb_var.bits_per_pixel+ 7)/ 8;
    screen_width = fb_var.xres;
    screen_height = fb_var.yres;
    // frame_base = mmap(0, fb_var.xres * fb_var.yres* fb_var.bits_per_pixel/ 8, PROT_READ|PROT_WRITE, MAP_PRIVATE, fb_fp, 0);
    frame_base = mmap(NULL, fb_var.xres * fb_var.yres* color_bits, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FILE, fb_fp, 0);
    if(MAP_FAILED == frame_base)
    {
        printf("Error mmap frame buffer.\n");
        return -1;
    }
    return 0;
}
void close_fb(void)
{
    munmap(frame_base, screen_width* screen_height* color_bits);
    close(fb_fp);
}
void TestMyGUI(void)
{
    int i;
    for(i=0; i<10; i++)
    {
        if(open_fb() > 0) 
        {
            set_fb();
            usleep(10000);
            close_fb();
        }
        else break;
    }
    printf("%s InitMyGUI OK %d. \n", __FUNCTION__, __LINE__);
    for(i=0; i<10; i++)
    {
        if(open_fb() > 0) 
        {
            set_fb();
            // SetGUIBackColor((i*8)%256, (i*10)%256, (i*12)%256);
            // GUIFillRect(0, 0, screen_width-1, screen_height-1);
            // GUIFillRect(10, 10, 100, 100);
            *(((int *)frame_base)+ 16101) = (((i*8)%256)<<16) | (((i*10)%256) <<8) | ((i*12)%256);
            usleep(10000);
            close_fb();
        }
        else break;
    } 
    printf("%s TestMyGUI OK %d. \n", __FUNCTION__, __LINE__);
}

I will check the kernel when I got some spare time.

I tried running the code listed above on a NIOSII processor. I got the following results.

# include <unistd.h># include <stdio.h># include <fcntl.h># include <linux/fb.h># include <sys/mman.h>
int main()
{
    int fbfd = 0;
    struct fb_var_screeninfo vinfo;
    struct fb_fix_screeninfo finfo;
    long int screensize = 0;
    char *fbp = 0;
    int x = 0, y = 0;
    long int location = 0;
    // Open the file for reading and writing
    fbfd = open("/dev/fb0", O_RDWR);
    if (!fbfd) {
        printf("Error: cannot open framebuffer device.\n");
        exit(1);
    }
    printf("The framebuffer device was opened successfully.\n");
    // Get fixed screen information
    if (ioctl(fbfd, FBIOGET_FSCREENINFO, &finfo)) {
        printf("Error reading fixed information.\n");
        exit(2);
    }
    // Get variable screen information
    if (ioctl(fbfd, FBIOGET_VSCREENINFO, &vinfo)) {
        printf("Error reading variable information.\n");
        exit(3);
    }
    printf("%dx%d, %dbpp\n", vinfo.xres, vinfo.yres, vinfo.bits_per_pixel );
    // Figure out the size of the screen in bytes
    screensize = vinfo.xres * vinfo.yres * vinfo.bits_per_pixel / 8;
    // Map the device to memory
    fbp = (char *)mmap(0, screensize, PROT_READ | PROT_WRITE, MAP_SHARED, fbfd, 0);
    if ((int)fbp == -1) {
        printf("Error: failed to map framebuffer device to memory.\n");
        exit(4);
    }
    printf("The framebuffer device was mapped to memory successfully.\n");
    x = 100; y = 100;       // Where we are going to put the pixel
    // Figure out where in memory to put the pixel
    for ( y = 100; y < 300; y++ )
        for ( x = 100; x < 300; x++ ) {
            location = (x+vinfo.xoffset) * (vinfo.bits_per_pixel/8) +
                       (y+vinfo.yoffset) * finfo.line_length;
            if ( vinfo.bits_per_pixel == 32 ) {
                *(fbp + location) = 100;        // Some blue
                *(fbp + location + 1) = 15+(x-100)/2;     // A little green
                *(fbp + location + 2) = 200-(y-100)/5;    // A lot of red
                *(fbp + location + 3) = 0;      // No transparency
            } else  { //assume 16bpp
                int b = 10;
                int g = (x-100)/6;     // A little green
                int r = 31-(y-100)/16;    // A lot of red
                unsigned short int t = r<<11 | g << 5 | b;
                *((unsigned short int*)(fbp + location)) = t;
            }
        }
    munmap(fbp, screensize);
    close(fbfd);
    return 0;
}

Hi All,

I found it was introduced since v2.6.29-rc1.

This issue was resolved. Please pull the updates, clean and rebuild.

please follow step4,5 in nios2-linux/README.