mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-12-29 17:25:38 +00:00
docs: console.txt: convert docs to ReST and rename to *.rst
Convert this small file to ReST in preparation for adding it to the driver-api book. While this is not part of the driver-api book, mark it as :orphan:, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Acked-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
This commit is contained in:
parent
01c0aa7943
commit
8db8acee4b
@ -1,3 +1,6 @@
|
||||
:orphan:
|
||||
|
||||
===============
|
||||
Console Drivers
|
||||
===============
|
||||
|
||||
@ -17,25 +20,26 @@ of driver occupying the consoles.) They can only take over the console that is
|
||||
occupied by the system driver. In the same token, if the modular driver is
|
||||
released by the console, the system driver will take over.
|
||||
|
||||
Modular drivers, from the programmer's point of view, have to call:
|
||||
Modular drivers, from the programmer's point of view, have to call::
|
||||
|
||||
do_take_over_console() - load and bind driver to console layer
|
||||
give_up_console() - unload driver; it will only work if driver
|
||||
is fully unbound
|
||||
|
||||
In newer kernels, the following are also available:
|
||||
In newer kernels, the following are also available::
|
||||
|
||||
do_register_con_driver()
|
||||
do_unregister_con_driver()
|
||||
|
||||
If sysfs is enabled, the contents of /sys/class/vtconsole can be
|
||||
examined. This shows the console backends currently registered by the
|
||||
system which are named vtcon<n> where <n> is an integer from 0 to 15. Thus:
|
||||
system which are named vtcon<n> where <n> is an integer from 0 to 15.
|
||||
Thus::
|
||||
|
||||
ls /sys/class/vtconsole
|
||||
. .. vtcon0 vtcon1
|
||||
|
||||
Each directory in /sys/class/vtconsole has 3 files:
|
||||
Each directory in /sys/class/vtconsole has 3 files::
|
||||
|
||||
ls /sys/class/vtconsole/vtcon0
|
||||
. .. bind name uevent
|
||||
@ -46,27 +50,29 @@ What do these files signify?
|
||||
read, or acts to bind or unbind the driver to the virtual consoles
|
||||
when written to. The possible values are:
|
||||
|
||||
0 - means the driver is not bound and if echo'ed, commands the driver
|
||||
0
|
||||
- means the driver is not bound and if echo'ed, commands the driver
|
||||
to unbind
|
||||
|
||||
1 - means the driver is bound and if echo'ed, commands the driver to
|
||||
1
|
||||
- means the driver is bound and if echo'ed, commands the driver to
|
||||
bind
|
||||
|
||||
2. name - read-only file. Shows the name of the driver in this format:
|
||||
2. name - read-only file. Shows the name of the driver in this format::
|
||||
|
||||
cat /sys/class/vtconsole/vtcon0/name
|
||||
(S) VGA+
|
||||
cat /sys/class/vtconsole/vtcon0/name
|
||||
(S) VGA+
|
||||
|
||||
'(S)' stands for a (S)ystem driver, i.e., it cannot be directly
|
||||
commanded to bind or unbind
|
||||
'(S)' stands for a (S)ystem driver, i.e., it cannot be directly
|
||||
commanded to bind or unbind
|
||||
|
||||
'VGA+' is the name of the driver
|
||||
'VGA+' is the name of the driver
|
||||
|
||||
cat /sys/class/vtconsole/vtcon1/name
|
||||
(M) frame buffer device
|
||||
cat /sys/class/vtconsole/vtcon1/name
|
||||
(M) frame buffer device
|
||||
|
||||
In this case, '(M)' stands for a (M)odular driver, one that can be
|
||||
directly commanded to bind or unbind.
|
||||
In this case, '(M)' stands for a (M)odular driver, one that can be
|
||||
directly commanded to bind or unbind.
|
||||
|
||||
3. uevent - ignore this file
|
||||
|
||||
@ -75,14 +81,17 @@ driver takes over the consoles vacated by the driver. Binding, on the other
|
||||
hand, will bind the driver to the consoles that are currently occupied by a
|
||||
system driver.
|
||||
|
||||
NOTE1: Binding and unbinding must be selected in Kconfig. It's under:
|
||||
NOTE1:
|
||||
Binding and unbinding must be selected in Kconfig. It's under::
|
||||
|
||||
Device Drivers -> Character devices -> Support for binding and unbinding
|
||||
console drivers
|
||||
Device Drivers ->
|
||||
Character devices ->
|
||||
Support for binding and unbinding console drivers
|
||||
|
||||
NOTE2: If any of the virtual consoles are in KD_GRAPHICS mode, then binding or
|
||||
unbinding will not succeed. An example of an application that sets the console
|
||||
to KD_GRAPHICS is X.
|
||||
NOTE2:
|
||||
If any of the virtual consoles are in KD_GRAPHICS mode, then binding or
|
||||
unbinding will not succeed. An example of an application that sets the
|
||||
console to KD_GRAPHICS is X.
|
||||
|
||||
How useful is this feature? This is very useful for console driver
|
||||
developers. By unbinding the driver from the console layer, one can unload the
|
||||
@ -92,10 +101,10 @@ framebuffer console to VGA console and vice versa, this feature also makes
|
||||
this possible. (NOTE NOTE NOTE: Please read fbcon.txt under Documentation/fb
|
||||
for more details.)
|
||||
|
||||
Notes for developers:
|
||||
=====================
|
||||
Notes for developers
|
||||
====================
|
||||
|
||||
do_take_over_console() is now broken up into:
|
||||
do_take_over_console() is now broken up into::
|
||||
|
||||
do_register_con_driver()
|
||||
do_bind_con_driver() - private function
|
||||
@ -104,7 +113,7 @@ give_up_console() is a wrapper to do_unregister_con_driver(), and a driver must
|
||||
be fully unbound for this call to succeed. con_is_bound() will check if the
|
||||
driver is bound or not.
|
||||
|
||||
Guidelines for console driver writers:
|
||||
Guidelines for console driver writers
|
||||
=====================================
|
||||
|
||||
In order for binding to and unbinding from the console to properly work,
|
||||
@ -140,6 +149,4 @@ The current crop of console drivers should still work correctly, but binding
|
||||
and unbinding them may cause problems. With minimal fixes, these drivers can
|
||||
be made to work correctly.
|
||||
|
||||
==========================
|
||||
Antonino Daplas <adaplas@pol.net>
|
||||
|
@ -187,7 +187,7 @@ the hardware. Thus, in a VGA console::
|
||||
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).
|
||||
Documentation/console/console.rst for more information).
|
||||
|
||||
This is more complicated in the case of the framebuffer console (fbcon),
|
||||
because fbcon is an intermediate layer between the console and the drivers::
|
||||
@ -204,7 +204,7 @@ 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:
|
||||
Documentation/console/console.rst. To summarize:
|
||||
|
||||
Echo a value to the bind file that represents the framebuffer console
|
||||
driver. So assuming vtcon1 represents fbcon, then::
|
||||
|
@ -93,7 +93,7 @@ config VT_HW_CONSOLE_BINDING
|
||||
select the console driver that will serve as the backend for the
|
||||
virtual terminals.
|
||||
|
||||
See <file:Documentation/console/console.txt> for more
|
||||
See <file:Documentation/console/console.rst> for more
|
||||
information. For framebuffer console users, please refer to
|
||||
<file:Documentation/fb/fbcon.rst>.
|
||||
|
||||
|
Loading…
Reference in New Issue
Block a user