X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=Documentation%2Ffb%2Ffbcon.txt;h=08dce0f631bf90cc322282d33f21ec6509a9307f;hb=9464c7cf61b9433057924c36e6e02f303a00e768;hp=f373df12ed4ce9bd236454495529387509359801;hpb=41689045f6a3cbe0550e1d34e9cc20d2e8c432ba;p=linux-2.6.git diff --git a/Documentation/fb/fbcon.txt b/Documentation/fb/fbcon.txt index f373df12e..08dce0f63 100644 --- a/Documentation/fb/fbcon.txt +++ b/Documentation/fb/fbcon.txt @@ -135,10 +135,10 @@ C. Boot options The angle can be changed anytime afterwards by 'echoing' the same numbers to any one of the 2 attributes found in - /sys/class/graphics/fbcon + /sys/class/graphics/fb{x} - rotate - rotate the display of the active console - rotate_all - rotate the display of all consoles + con_rotate - rotate the display of the active console + con_rotate_all - rotate the display of all consoles Console rotation will only become available if Console Rotation Support is compiled in your kernel. @@ -148,177 +148,5 @@ C. Boot options Actually, the underlying fb driver is totally ignorant of console rotation. -C. Attaching, Detaching and Unloading - -Before going on on how to attach, detach and unload the framebuffer console, an -illustration of the dependencies may help. - -The console layer, as with most subsystems, needs a driver that interfaces with -the hardware. Thus, in a VGA console: - -console ---> VGA driver ---> hardware. - -Assuming the VGA driver can be unloaded, one must first unbind the VGA driver -from the console layer before unloading the driver. The VGA driver cannot be -unloaded if it is still bound to the console layer. (See -Documentation/console/console.txt for more information). - -This is more complicated in the case of the the framebuffer console (fbcon), -because fbcon is an intermediate layer between the console and the drivers: - -console ---> fbcon ---> fbdev drivers ---> hardware - -The fbdev drivers cannot be unloaded if it's bound to fbcon, and fbcon cannot -be unloaded if it's bound to the console layer. - -So to unload the fbdev drivers, one must first unbind fbcon from the console, -then unbind the fbdev drivers from fbcon. Fortunately, unbinding fbcon from -the console layer will automatically unbind framebuffer drivers from -fbcon. Thus, there is no need to explicitly unbind the fbdev drivers from -fbcon. - -So, how do we unbind fbcon from the console? Part of the answer is in -Documentation/console/console.txt. To summarize: - -Echo a value to the bind file that represents the framebuffer console -driver. So assuming vtcon1 represents fbcon, then: - -echo 1 > sys/class/vtconsole/vtcon1/bind - attach framebuffer console to - console layer -echo 0 > sys/class/vtconsole/vtcon1/bind - detach framebuffer console from - console layer - -If fbcon is detached from the console layer, your boot console driver (which is -usually VGA text mode) will take over. A few drivers (rivafb and i810fb) will -restore VGA text mode for you. With the rest, before detaching fbcon, you -must take a few additional steps to make sure that your VGA text mode is -restored properly. The following is one of the several methods that you can do: - -1. Download or install vbetool. This utility is included with most - distributions nowadays, and is usually part of the suspend/resume tool. - -2. In your kernel configuration, ensure that CONFIG_FRAMEBUFFER_CONSOLE is set - to 'y' or 'm'. Enable one or more of your favorite framebuffer drivers. - -3. Boot into text mode and as root run: - - vbetool vbestate save > - - The above command saves the register contents of your graphics - hardware to . You need to do this step only once as - the state file can be reused. - -4. If fbcon is compiled as a module, load fbcon by doing: - - modprobe fbcon - -5. Now to detach fbcon: - - vbetool vbestate restore < && \ - echo 0 > /sys/class/vtconsole/vtcon1/bind - -6. That's it, you're back to VGA mode. And if you compiled fbcon as a module, - you can unload it by 'rmmod fbcon' - -7. To reattach fbcon: - - echo 1 > /sys/class/vtconsole/vtcon1/bind - -8. Once fbcon is unbound, all drivers registered to the system will also -become unbound. This means that fbcon and individual framebuffer drivers -can be unloaded or reloaded at will. Reloading the drivers or fbcon will -automatically bind the console, fbcon and the drivers together. Unloading -all the drivers without unloading fbcon will make it impossible for the -console to bind fbcon. - -Notes for vesafb users: -======================= - -Unfortunately, if your bootline includes a vga=xxx parameter that sets the -hardware in graphics mode, such as when loading vesafb, vgacon will not load. -Instead, vgacon will replace the default boot console with dummycon, and you -won't get any display after detaching fbcon. Your machine is still alive, so -you can reattach vesafb. However, to reattach vesafb, you need to do one of -the following: - -Variation 1: - - a. Before detaching fbcon, do - - vbetool vbemode save > # do once for each vesafb mode, - # the file can be reused - - b. Detach fbcon as in step 5. - - c. Attach fbcon - - vbetool vbestate restore < && \ - echo 1 > /sys/class/vtconsole/vtcon1/bind - -Variation 2: - - a. Before detaching fbcon, do: - echo > /sys/class/tty/console/bind - - - vbetool vbemode get - - b. Take note of the mode number - - b. Detach fbcon as in step 5. - - c. Attach fbcon: - - vbetool vbemode set && \ - echo 1 > /sys/class/vtconsole/vtcon1/bind - -Samples: -======== - -Here are 2 sample bash scripts that you can use to bind or unbind the -framebuffer console driver if you are in an X86 box: - ---------------------------------------------------------------------------- -#!/bin/bash -# Unbind fbcon - -# Change this to where your actual vgastate file is located -# Or Use VGASTATE=$1 to indicate the state file at runtime -VGASTATE=/tmp/vgastate - -# path to vbetool -VBETOOL=/usr/local/bin - - -for (( i = 0; i < 16; i++)) -do - if test -x /sys/class/vtconsole/vtcon$i; then - if [ `cat /sys/class/vtconsole/vtcon$i/name | grep -c "frame buffer"` \ - = 1 ]; then - if test -x $VBETOOL/vbetool; then - echo Unbinding vtcon$i - $VBETOOL/vbetool vbestate restore < $VGASTATE - echo 0 > /sys/class/vtconsole/vtcon$i/bind - fi - fi - fi -done - ---------------------------------------------------------------------------- -#!/bin/bash -# Bind fbcon - -for (( i = 0; i < 16; i++)) -do - if test -x /sys/class/vtconsole/vtcon$i; then - if [ `cat /sys/class/vtconsole/vtcon$i/name | grep -c "frame buffer"` \ - = 1 ]; then - echo Unbinding vtcon$i - echo 1 > /sys/class/vtconsole/vtcon$i/bind - fi - fi -done ---------------------------------------------------------------------------- - --- +--- Antonino Daplas