Linux and UNIX Man Pages

Linux & Unix Commands - Search Man Pages

vkbd(4) [freebsd man page]

VKBD(4) 						   BSD Kernel Interfaces Manual 						   VKBD(4)

vkbd -- the virtual AT keyboard interface SYNOPSIS
device vkbd DESCRIPTION
The vkbd interface is a software loopback mechanism that can be loosely described as the virtual AT keyboard analog of the pty(4), that is, vkbd does for virtual AT keyboards what the pty(4) driver does for terminals. The vkbd driver, like the pty(4) driver, provides two interfaces: a keyboard interface like the usual facility it is simulating (a virtual AT keyboard in the case of vkbd, or a terminal for pty(4)), and a character-special device ``control'' interface. The virtual AT keyboards are named vkbd0, vkbd1, etc., one for each control device that has been opened. The vkbd interface permits opens on the special control device /dev/vkbdctl. When this device is opened, vkbd will return a handle for the lowest unused vkbdctl device (use devname(3) to determine which). Each virtual AT keyboard supports the usual keyboard interface ioctl(2)s, and thus can be used with kbdcontrol(1) like any other keyboard. The control device supports exactly the same ioctl(2)s as the virtual AT keyboard device. Writing AT scan codes to the control device gener- ates an input on the virtual AT keyboard, as if the (non-existent) hardware had just received it. The virtual AT keyboard control device, normally /dev/vkbdctl<N>, is exclusive-open (it cannot be opened if it is already open) and is restricted to the super-user. A read(2) call will return the virtual AT keyboard status structure (defined in <dev/vkbd/vkbd_var.h>) if one is available; if not, it will either block until one is or return EWOULDBLOCK, depending on whether non-blocking I/O has been enabled. A write(2) call passes AT scan codes to be ``received'' from the virtual AT keyboard. Each AT scan code must be passed as unsigned int. Although AT scan codes must be passes as unsigned ints, the size of the buffer passed to write(2) still should be in bytes, i.e., static unsigned int codes[] = { /* Make Break */ 0x1e, 0x9e }; int main(void) { int fd, len; fd = open("/dev/vkbdctl0", O_RDWR); if (fd < 0) err(1, "open"); /* Note sizeof(codes) - not 2! */ len = write(fd, codes, sizeof(codes)); if (len < 0) err(1, "write"); close(fd); return (0); } Write will block if there is not enough space in the input queue. The control device also supports select(2) for read and write. On the last close of the control device, the virtual AT keyboard is removed. All queued scan codes are thrown away. SEE ALSO
kbdcontrol(1), atkbdc(4), psm(4), syscons(4), vt(4) HISTORY
The vkbd module was implemented in FreeBSD 6.0. AUTHORS
Maksim Yevmenkin <> CAVEATS
The vkbd interface is a software loopback mechanism, and, thus ddb(4) will not work with it. Current implementation of the syscons(4) driver can accept input from only one keyboard, even if it is virtual. Thus it is not possible to have both wired and virtual keyboard to be active at the same time. It is, however, in principal possible to obtain AT scan codes from the different sources and write them into the same vir- tual keyboard. The virtual keyboard state synchronization is the user's responsibility. BSD
August 12, 2004 BSD

Check Out this Related Man Page

UKBD(4) 						   BSD Kernel Interfaces Manual 						   UKBD(4)

ukbd -- USB keyboard driver SYNOPSIS
To compile this driver into the kernel, place the following line in your kernel configuration file: device ukbd Alternatively, to load the driver as a module at boot time, place the following line in loader.conf(5): ukbd_load="YES" DESCRIPTION
The ukbd driver provides support for keyboards that attach to the USB port. usb(4) and one of uhci(4) or ohci(4) must be configured in the kernel as well. CONFIGURATION
By default, the keyboard subsystem does not create the appropriate devices yet. Make sure you reconfigure your kernel with the following option in the kernel config file: options KBD_INSTALL_CDEV If both an AT keyboard USB keyboards are used at the same time, the AT keyboard will appear as kbd0 in /dev. The USB keyboards will be kbd1, kbd2, etc. You can see some information about the keyboard with the following command: kbdcontrol -i < /dev/kbd1 or load a keymap with kbdcontrol -l keymaps/pt.iso < /dev/kbd1 See kbdcontrol(1) for more possible options. You can swap console keyboards by using the command kbdcontrol -k /dev/kbd1 From this point on, the first USB keyboard will be the keyboard to be used by the console. If you want to use a USB keyboard as your default and not use an AT keyboard at all, you will have to remove the device atkbd line from the kernel configuration file. Because of the device initialization order, the USB keyboard will be detected after the console driver initial- izes itself and you have to explicitly tell the console driver to use the existence of the USB keyboard. This can be done in one of the fol- lowing two ways. Run the following command as a part of system initialization: kbdcontrol -k /dev/kbd0 < /dev/ttyv0 > /dev/null (Note that as the USB keyboard is the only keyboard, it is accessed as /dev/kbd0) or otherwise tell the console driver to periodically look for a keyboard by setting a flag in the kernel configuration file: device sc0 at isa? flags 0x100 With the above flag, the console driver will try to detect any keyboard in the system if it did not detect one while it was initialized at boot time. DRIVER CONFIGURATION
options KBD_INSTALL_CDEV Make the keyboards available through a character device in /dev. options UKBD_DFLT_KEYMAP makeoptions UKBD_DFLT_KEYMAP=fr.iso The above lines will put the French ISO keymap in the ukbd driver. You can specify any keymap in /usr/share/syscons/keymaps with this option. options KBD_DISABLE_KEYMAP_LOADING Do not allow the user to change the keymap. Note that these options also affect the AT keyboard driver, atkbd(4). FILES
/dev/kbd* blocking device nodes EXAMPLES
device ukbd Add the ukbd driver to the kernel. SEE ALSO
kbdcontrol(1), ohci(4), syscons(4), uhci(4), usb(4), config(8) AUTHORS
The ukbd driver was written by Lennart Augustsson <> for NetBSD and was substantially rewritten for FreeBSD by Kazutaka YOKOTA <>. This manual page was written by Nick Hibma <> with a large amount of input from Kazutaka YOKOTA <>. BSD
November 22, 2006 BSD
Man Page

Featured Tech Videos