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authorTimothy Pearson <kb9vqf@pearsoncomputing.net>2011-11-08 12:31:36 -0600
committerTimothy Pearson <kb9vqf@pearsoncomputing.net>2011-11-08 12:31:36 -0600
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+/****************************************************************************
+**
+** Windowsystem-specific pages
+**
+** Copyright (C) 2000-2008 Trolltech ASA. All rights reserved.
+**
+** This file is part of the Qt GUI Toolkit.
+**
+** This file may be used under the terms of the GNU General
+** Public License versions 2.0 or 3.0 as published by the Free
+** Software Foundation and appearing in the files LICENSE.GPL2
+** and LICENSE.GPL3 included in the packaging of this file.
+** Alternatively you may (at your option) use any later version
+** of the GNU General Public License if such license has been
+** publicly approved by Trolltech ASA (or its successors, if any)
+** and the KDE Free Qt Foundation.
+**
+** Please review the following information to ensure GNU General
+** Public Licensing retquirements will be met:
+** http://trolltech.com/products/qt/licenses/licensing/opensource/.
+** If you are unsure which license is appropriate for your use, please
+** review the following information:
+** http://trolltech.com/products/qt/licenses/licensing/licensingoverview
+** or contact the sales department at sales@trolltech.com.
+**
+** This file may be used under the terms of the Q Public License as
+** defined by Trolltech ASA and appearing in the file LICENSE.QPL
+** included in the packaging of this file. Licensees holding valid Qt
+** Commercial licenses may use this file in accordance with the Qt
+** Commercial License Agreement provided with the Software.
+**
+** This file is provided "AS IS" with NO WARRANTY OF ANY KIND,
+** INCLUDING THE WARRANTIES OF DESIGN, MERCHANTABILITY AND FITNESS FOR
+** A PARTICULAR PURPOSE. Trolltech reserves all rights not granted
+** herein.
+**
+**********************************************************************/
+
+/*!
+\page emb-framebuffer-howto.html
+
+\title Enabling the Linux Framebuffer
+
+This is only a short guide.
+See \l file:/usr/src/linux/README and
+\l file:/usr/src/linux/Documentation/fb/ for detailed information.
+There is also a detailed explanation at
+\l http://www.linuxdoc.org/HOWTO/Framebuffer-HOWTO.html.
+
+\list 1
+\i Make sure that you have the Linux kernel source code in
+\l file:/usr/src/linux/.
+
+\i Log in as root and \c cd \c /usr/src/linux
+
+\i Configure the kernel:
+
+ Run:
+\code
+ make menuconfig
+\endcode
+
+ 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.
+
+\i Compile the kernel
+
+ First do:
+\code
+ make dep
+\endcode
+ then:
+\code
+ make bzImage
+\endcode
+
+ The new kernel should now be in arch/i386/boot/bzImage.
+
+\i Copy the kernel to the boot directory:
+\code
+ cp arch/i386/boot/bzImage /boot/linux.vesafb
+\endcode
+
+\i Edit /etc/lilo.conf.
+
+ \warning Keep a backup of \l file:/etc/lilo.conf, and have a rescue disk
+ available. If you make a mistake, the machine may not boot.
+
+ The file \l file:/etc/lilo.conf specifies how the system boots. The
+ precise contents of the file varies from system to system. Here is
+ an example:
+\code
+# 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
+\endcode
+
+ Make a new "image" section that is a copy of the first one, but with
+\code
+ image = /boot/linux.vesafb
+\endcode
+ and
+\code
+ label = Linux-vesafb
+\endcode
+ Place it just above the first image section.
+
+ Add a line before the image section saying \c{vga = 791}. (Meaning
+ 1024x768, 16 bpp.)
+
+ With the above example, lilo.conf would now be:
+\code
+# 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
+\endcode
+
+Do not change any existing lines in the file; just add new ones.
+
+\i To make the new changes take effect, run the lilo program:
+\code
+ lilo
+\endcode
+
+\i Reboot the system. You should now see a penguin logo while the
+ system is booting.
+ (Or more than one on a multi-processor machine.)
+
+\i 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 \l
+ file:/etc/lilo.conf from backup and re-run lilo.
+
+\i Testing: Here's a short program that opens the frame buffer and draws a
+ gradient-filled red square.
+
+\code
+#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;
+}
+\endcode
+\endlist
+
+*/