The angle can be changed anytime afterwards by 'echoing' the same
numbers to any one of the 2 attributes found in
- /sys/class/graphics/fb{x}
+ /sys/class/graphics/fbcon
- con_rotate - rotate the display of the active console
- con_rotate_all - rotate the display of all consoles
+ rotate - rotate the display of the active console
+ rotate_all - rotate the display of all consoles
Console rotation will only become available if Console Rotation
Support is compiled in your kernel.
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 > <vga state file>
+
+ The above command saves the register contents of your graphics
+ hardware to <vga state file>. 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 < <vga state file> && \
+ 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 > <vesa state file> # do once for each vesafb mode,
+ # the file can be reused
+
+ b. Detach fbcon as in step 5.
+
+ c. Attach fbcon
+
+ vbetool vbestate restore < <vesa state file> && \
+ echo 1 > /sys/class/vtconsole/vtcon1/bind
+
+Variation 2:
+
+ a. Before detaching fbcon, do:
+ echo <ID> > /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 <mode number> && \
+ 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 <adaplas@pol.net>
git.openpandora.org / pandora-kernel.git / blobdiff