At boot, the console output is sent to all the devices
listed in
console.write. The
list is a comma separated set of driver names (the serial
devices must be bracketed and may contain additional
parameters). Likewise for the console input using the
console.read non volatile
variable. When these variables are not set they default to
all-wr and all-rd
respectively.
The current active drivers may be displayed with:
console -lThe output of this command is split into two sections for the write(console output) and read(console input).
Example 5.3. Showing the consoles of an unconfigured system
>nvshow console.write console.write (is unset) >nvshow console.read console.read (is unset) >console -l Console (write): all write: => s3c2410x-video: S3C24XX Framebuffer (640x480 @ 60Hz, 31.5 KHz) => null: NULL => serial: low level serial Console (read): all read: => usbkbd: USB Keyboard Driver => null: NULL => serial: low level serial >
Once a system is running it is sometimes useful to add an additional driver. Adding a driver allows access to ABLE on that new device. This can be especially useful in scripts which can add displays based upon shell decisions. Section 5.5, “Practical use of the console system” contains more examples on using this feature.
Example 5.4. Adding console drivers to a running system
This example shows the adding of the second s3c2410 serial port, once added the serial port can be used to interact with ABLE
>console -l Console (write): all write: => s3c2410x-video: S3C24XX Framebuffer (640x480 @ 60Hz, 31.5 KHz) => null: NULL => serial: low level serial Console (read): all read: => usbkbd: USB Keyboard Driver => null: NULL => serial: low level serial >console -a (s3c2410_serial1) adding console (s3c2410_serial1) >console -l Console (write): all write: => (s3c2410_serial1): fd (s3c2410_serial1) => s3c2410x-video: S3C24XX Framebuffer (640x480 @ 60Hz, 31.5 KHz) => null: NULL => serial: low level serial Console (read): all read: => (s3c2410_serial1): fd (s3c2410_serial1) => usbkbd: USB Keyboard Driver => null: NULL => serial: low level serial >