From bd0f3345a938b35ce6a12f6150373b0955b8dd12 Mon Sep 17 00:00:00 2001 From: Timothy Pearson Date: Sun, 10 Jul 2011 15:24:15 -0500 Subject: Add Qt3 development HEAD version --- doc/html/emb-framebuffer-howto.html | 234 ++++++++++++++++++++++++++++++++++++ 1 file changed, 234 insertions(+) create mode 100644 doc/html/emb-framebuffer-howto.html (limited to 'doc/html/emb-framebuffer-howto.html') diff --git a/doc/html/emb-framebuffer-howto.html b/doc/html/emb-framebuffer-howto.html new file mode 100644 index 0000000..df6291e --- /dev/null +++ b/doc/html/emb-framebuffer-howto.html @@ -0,0 +1,234 @@ + + + + + +Enabling the Linux Framebuffer + + + + + + + +
+ +Home + | +All Classes + | +Main Classes + | +Annotated + | +Grouped Classes + | +Functions +

Enabling the Linux Framebuffer

+ + + +

This is only a short guide. +See /usr/src/linux/README and +/usr/src/linux/Documentation/fb/ for detailed information. +There is also a detailed explanation at +http://www.linuxdoc.org/HOWTO/Framebuffer-HOWTO.html. +

    +
  1. Make sure that you have the Linux kernel source code in +/usr/src/linux/. +

  2. Log in as root and cd /usr/src/linux +

  3. Configure the kernel: +

    Run: +

    +    make menuconfig
+
    + +

    Select "Code maturity level options" and set "Prompt for +development and/or incomplete code/drivers". +

    Then select "Console drivers" and set "Support for frame buffer +devices" to built-in (even if it says EXPERIMENTAL). Then configure +the driver. Most modern graphics cards can use the "VESA VGA +graphics console"; use that or a driver that specifically matches +your video card. Finally, enable "Advanced low level driver options" +and make sure that 16 and 32 bpp packed pixel support are enabled. +

    When you are finished, chose exit and save. +

  4. Compile the kernel +

    First do: +

    +    make dep
+
    + +then: +
    +    make bzImage
+
    + +

    The new kernel should now be in arch/i386/boot/bzImage. +

  5. Copy the kernel to the boot directory: +
    +    cp arch/i386/boot/bzImage /boot/linux.vesafb
+
    + +

  6. Edit /etc/lilo.conf. +

    Warning: Keep a backup of /etc/lilo.conf, and have a rescue disk +available. If you make a mistake, the machine may not boot. +

    The file /etc/lilo.conf specifies how the system boots. The +precise contents of the file varies from system to system. Here is +an example: +

    +# LILO configuration file
+boot = /dev/hda3
+delay = 30 
+image = /boot/vmlinuz
+  root = /dev/hda3
+  label = Linux
+  read-only # Non-UMSDOS filesystems should be mounted read-only for checking
+other=/dev/hda1
+        label=nt
+        table=/dev/hda
+
    + +

    Make a new "image" section that is a copy of the first one, but with +

    +  image = /boot/linux.vesafb 
+
    + +and +
    +  label = Linux-vesafb
+
    + +Place it just above the first image section. +

    Add a line before the image section saying vga = 791. (Meaning +1024x768, 16 bpp.) +

    With the above example, lilo.conf would now be: +

    +# LILO configuration file
+boot = /dev/hda3
+delay = 30 
+vga = 791
+image = /boot/linux.vesafb
+  root = /dev/hda3
+  label = Linux-vesafb
+  read-only # Non-UMSDOS filesystems should be mounted read-only for checking
+image = /boot/vmlinuz
+  root = /dev/hda3
+  label = Linux
+  read-only # Non-UMSDOS filesystems should be mounted read-only for checking
+other=/dev/hda1
+        label=nt
+        table=/dev/hda
+
    + +

    Do not change any existing lines in the file; just add new ones. +

  7. To make the new changes take effect, run the lilo program: +
    +    lilo
+
    + +

  8. Reboot the system. You should now see a penguin logo while the +system is booting. +(Or more than one on a multi-processor machine.) +

  9. If it does not boot properly with the new kernel, you can boot with +the old kernel by entering the label of the old image section at +the LILO prompt. (with the example lilo.conf file, the old label is +Linux.) +

    If that does not work (probably because of an error in lilo.conf), +boot the machine using your rescue disk, restore /etc/lilo.conf from backup and re-run lilo. +

  10. Testing: Here's a short program that opens the frame buffer and draws a +gradient-filled red square. +

    +#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;
+}
+
    + +
+

+ +

+ +
Copyright © 2007 +TrolltechTrademarks +
Qt 3.3.8
+
+ -- cgit v1.2.3