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25 .TH Xdmx 1 __vendorversion__
27 Xdmx - Distributed Multi-head X server
30 [:display] [option ...]
33 is a proxy X server that uses one or more other X servers as its display
34 devices. It provides multi-head X functionality for displays that might
35 be located on different machines.
37 functions as a front-end X server that acts as a proxy to a set of
38 back-end X servers. All of the visible rendering is passed to the
39 back-end X servers. Clients connect to the
41 front-end, and everything appears as it would in a regular multi-head
42 configuration. If Xinerama is enabled (e.g., with
44 on the command line), the clients see a single large screen.
47 communicates to the back-end X servers using the standard X11 protocol,
48 and standard and/or commonly available X server extensions.
50 In addition to the normal X server options described in the
51 .I Xserver(__appmansuffix__)
54 accepts the following command line switches:
56 .BI "\-display " display-name
57 This specifies the name(s) of the back-end X server display(s) to connect
58 to. This option may be specified multiple times to connect to more than
59 one back-end display. The first is used as screen 0, the second as screen 1,
60 etc. If this option is omitted, the
62 environment variable is used as the single back-end X server display.
65 .BI "\-xinput " input-source
66 This specifies the source to use for XInput extension devices. The
67 choices are the same as for
69 described below, except that core devices on backend servers cannot be
70 treated as XInput extension devices. (Although extension devices on
71 backend and console servers are supported as extension devices under
75 .BI "\-input " input-source
76 This specifies the source to use for the core input devices. The choices are:
80 A set of dummy core input drivers are used. These never generate any
85 The raw keyboard and pointer from the local computer are used. A
86 comma-separated list of driver names can be appended. For example, to
87 select the example Linux keyboard and PS/2 mouse driver use:
88 .BR "-input local,kbd,ps2" .
89 The following drivers have been implemented for Linux: kbd, ms (a
90 two-button Microsoft mouse driver), ps2 (a PS/2 mouse driver), usb-mou
91 (a USB mouse driver), usb-kbd (a USB keyboard driver), and usb-oth (a
92 USB non-keyboard, non-mouse driver). Additional drivers may be
93 implemented in the future. Appropriate defaults will be used if no
94 comma-separated list is provided.
98 If the display-name is a back-end server, then core input events are
99 taken from the server specified. Otherwise, a console window will be
100 opened on the specified display.
104 is followed by ",xi" then XInput extension devices on the display will
107 XInput extension devices. If the
109 is followed by ",noxi" then XInput extension devices on the display will
113 XInput extension devices. Currently, the default is ",xi".
117 is followed by ",console" and the
119 refers to a display that is used as a backend display, then a console
120 window will be opened on that display
122 that display will be treated as a backend display. Otherwise (or if
123 ",noconsole" is used), the display will be treated purely as a backend
124 or a console display, as described above.
128 is followed by ",windows", then outlines of the windows on the backend
129 will be displayed inside the console window. Otherwise (or if
130 ",nowindows" is used), the console window will not display the outlines
131 of backend windows. (This option only applies to console input.)
135 is followed by ",xkb", then the next 1 to 3 comma-separated parameters
136 will specify the keycodes, symbols, and geometry of the keyboard for
137 this input device. For example, ",xkb,xfree86,pc104" will specify that
138 the "xfree86" keycodes and the "pc104" symbols should be used to
139 initialize the keyboard. For an SGI keyboard, ",xkb,sgi/indy(pc102)"
140 might be useful. A list of keycodes, symbols, and geometries can be
143 Use of keycodes, symbols and geometries for XKB configuration is
144 deprecated in favor of the rules, layout, model, variant and options
145 settings available via the -param command line switch.
146 If this option is not specified, the input device will be queried,
147 perhaps using the XKEYBOARD extension.
151 If this option isn't specified, the default input source is the first
152 back-end server (the one used for screen 0). The console window shows
153 the layout of the back-end display(s) and pointer movements and key
154 presses within the console window will be used as core input devices.
156 Several special function keys are active, depending on the input
167 server grab in console mode (a special cursor, currently a spider, is
168 used to indicate an active server grab).
171 will toggle fine-grain motion in console mode (a special cursor,
172 currently a cross hair, is used to indicate this mode). If this mode is
173 combined with a server grab, then the cursor will have 4 lines instead
176 .BR Ctrl-Alt-F1 " through " Ctrl-Alt-F12
177 will switch to another VC in local (raw) mode.
183 This option turns off support for displaying multiple cursors on
184 overlapped back-end displays. This option is available for testing and
185 benchmarking purposes.
191 server's default font path. This option can be specified multiple times
192 to accommodate multiple font paths. See the
194 section below for very important information regarding setting the
198 .BI "-configfile " filename
199 Specify the configuration file that should be read. Note that if the
201 command-line option is used, then the configuration file will be
206 Specify a configuration to use. The
208 will be the name following the
210 keyword in the configuration file.
213 .BI "-stat " "interval screens"
214 This option enables the display of performance statistics. The interval
215 is in seconds. The screens is a count of the number of back-end screens
216 for which data is printed each interval. Specifying 0 for screens will
217 display data for all screens.
219 For each screen, the following information is printed: the screen
220 number, an absolute count of the number of XSync() calls made
221 (SyncCount), the rate of these calls during the previous interval
222 (Sync/s), the average round-trip time (in microseconds) of the last 10
223 XSync() calls (avSync), the maximum round-trip time (in microseconds) of
224 the last 10 XSync calls (mxSync), the average number of XSync() requests
225 that were pending but not yet processed for each of the last 10
226 processed XSync() calls, the maximum number of XSync() requests that
227 were pending but not yet processed for each of the last 10 processed
228 XSync() calls, and a histogram showing the distribution of the times of
229 all of the XSync() calls that were made during the previous interval.
231 (The length of the moving average and the number and value of histogram
232 bins are configurable at compile time in the
237 .BI "-syncbatch " interval
240 in milliseconds for XSync() batching. An
242 less than or equal to 0 will disable XSync() batching. The default
247 .BI "-nooffscreenopt"
248 This option disables the offscreen optimization. Since the lazy window
249 creation optimization requires the offscreen optimization to be enabled,
250 this option will also disable the lazy window creation optimization.
254 This option disables the lazy window creation optimization.
258 This option disables the primitive subdivision optimization.
262 Disable use of the XKB extension for communication with the back end
263 displays. (Combine with
265 to disable all use of XKB.)
269 This option sets the root window's default depth. When choosing a
270 default visual from those available on the back-end X server, the first
271 visual with that matches the depth specified is used.
273 This option can be combined with the
275 option, which specifies the default color visual class, to force the use
276 of a specific depth and color class for the root window.
280 This option disables the RENDER extension.
284 This option disables GLX proxy -- the build-in GLX extension
285 implementation that is DMX aware.
288 .BI "-noglxswapgroup"
289 This option disables the swap group and swap barrier extensions in GLX
294 This option enables synchronization after a swap buffers call by waiting
295 until all X protocol has been processed. When a client issues a
296 glXSwapBuffers request, Xdmx relays that request to each back-end X
297 server, and those requests are buffered along with all other protocol
298 requests. However, in systems that have large network buffers, this
299 buffering can lead to the set of back-end X servers handling the swap
300 buffers request asynchronously. With this option, an XSync() request is
301 issued to each back-end X server after sending the swap buffers request.
302 The XSync() requests will flush all buffered protocol (including the
303 swap buffers requests) and wait until the back-end X servers have
304 processed those requests before continuing. This option does not wait
305 until all GL commands have been processed so there might be previously
306 issued commands that are still being processed in the GL pipe when the
307 XSync() request returns. See the
309 option below if Xdmx should wait until the GL commands have been
314 This option enables synchronization after a swap buffers call by waiting
315 until all GL commands have been completed. It is similar to the
317 option above; however, instead of issuing an XSync(), it issues a
318 glFinish() request to each back-end X server after sending the swap
319 buffers requests. The glFinish() request will flush all buffered
320 protocol requests, process both X and GL requests, and wait until all
321 previously called GL commands are complete before returning.
324 .BI "-ignorebadfontpaths"
325 This option ignores font paths that are not available on all back-end
326 servers by removing the bad font path(s) from the default font path
327 list. If no valid font paths are left after removing the bad paths, an
328 error to that effect is printed in the log.
331 .BI "-addremovescreens"
332 This option enables the dynamic addition and removal of screens, which
333 is disabled by default. Note that GLXProxy and Render do not yet
334 support dynamic addition and removal of screens, and must be disabled
339 command line options described above.
343 This option specifies parameters on the command line. Currently, only
344 parameters dealing with XKEYBOARD configuration are supported. These
345 parameters apply only to the core keyboard. Parameter values are
346 installation-dependent. Please see
348 or a similar directory for complete information.
352 Defaults to "__XKB_DFLT_RULES__". Other values may include "sgi" and "sun".
356 Defaults to "__XKB_DFLT_MODEL__". When used with "base" rules, other values
357 may include "pc102", "pc104", "microsoft", and many others. When
358 used with "sun" rules, other values may include "type4" and "type5".
362 Defaults to "__XKB_DFLT_LAYOUT__". Other country codes and "dvorak" are usually
367 Defaults to "__XKB_DFLT_VARIANT__".
371 Defaults to "__XKB_DFLT_OPTIONS__".
373 .SH "CONFIGURATION FILE GRAMMAR"
374 The following words and tokens are reserved:
387 Comments start with a
389 mark and extend to the end of the line. They may appear anywhere. If a
390 configuration file is read into
392 the comments in that file will be preserved, but will not be editable.
394 The grammar is as follows:
396 virtual-list ::= [ virtual-list ] | virtual
405 dw-list ::= [ dw-list ] | dw
407 dw ::= display | wall | option
411 name [ geometry ] [ / geometry ] [ origin ]
416 [ dim ] [ dim ] name-list
434 param-list ::= [ param-list ] | name-list
437 name-list ::= [ name-list ] | name
439 name ::= string | double-quoted-string
445 geometry ::= [ integer
447 integer ] [ signed-integer signed-integer ]
458 is used as an identifier for the configuration, and may be passed to
462 command line option. The name of a display should be standard X display
463 name, although no checking is performed (e.g., "machine:0").
465 For names, double quotes are optional unless the name is reserved or
468 The first dimension following
470 is the dimension for tiling (e.g., 2x4 or 4x4). The second dimension
473 is the dimension of each display in the wall (e.g., 1280x1024).
475 The first geometry following
477 is the geometry of the screen window on the backend server. The second
478 geometry, which is always preceeded by a slash, is the geometry of the
479 root window. By default, the root window has the same geometry as the
484 line can be used to specify any command-line options (e.g.,
486 (It cannot be used to specify the name of the front-end display.) The
487 option line is processed once at server startup, just line command line
488 options. This behavior may be unexpected.
489 .SH "CONFIGURATION FILE EXAMPLES"
490 Two displays being used for a desktop may be specified in any of the
495 display d0:0 1280x1024 @0x0;
496 display d1:0 1280x1024 @1280x0;
500 display d0:0 1280x1024;
501 display d1:0 @1280x0;
506 display "d1:0" @1280x0;
509 virtual example3 { wall 2x1 d0:0 d1:0; }
512 A 4x4 wall of 16 total displays could be specified as follows (if no
513 tiling dimension is specified, an approximate square is used):
517 wall d0:0 d1:0 d2:0 d3:0
525 The font path used by the
527 front-end server will be propagated to each back-end server,which
528 requires that each back-end server have access to the exact same font
529 paths as the front-end server. This can be most easily handled by
530 either using a font server (e.g., xfs) or by remotely mounting the font
531 paths on each back-end server, and then setting the
533 server's default font path with the
535 command line option described above.
537 For example, if you specify a font path with the following command line:
539 Xdmx :1 -display d0:0 -fontpath /usr/fonts/75dpi/ -fontpath /usr/fonts/Type1/ +xinerama
541 Then, /usr/fonts/75dpi/ and /usr/fonts/Type1/ must be valid font paths
544 server and all back-end server, which is d0 in this example.
546 Font servers can also be specified with the
548 option. For example, let's assume that a properly configured font
549 server is running on host d0. Then, the following command line
551 Xdmx :1 -display d0:0 -display d1:0 -fontpath tcp/d0:7100 +xinerama
553 will initialize the front-end
555 server and each of the back-end servers to use the font server on d0.
557 Some fonts might not be supported by either the front-end or the
558 back-end servers. For example, let's assume the front-end
560 server includes support Type1 fonts, but one of the back-end servers
561 does not. Let's also assume that the default font path for
563 includes Type1 fonts in its font path. Then, when
565 initializes the default font path to load the default font, the font
566 path that includes Type1 fonts (along with the other default font paths
569 server) is sent to the back-end server that cannot handle Type1 fonts.
570 That back-end server then rejects the font path and sends an error back
575 then prints an error message and exits because it failed to set the
576 default font path and was unable load the default font.
578 To fix this error, the offending font path must be removed from the
579 default font path by using a different
585 option can also be added to the configuration file as described above.
586 .SH "COMMAND-LINE EXAMPLES"
587 The back-end machines are d0 and d1, core input is from the pointer and
588 keyboard attached to d0, clients will refer to :1 when opening windows:
590 Xdmx :1 -display d0:0 -display d1:0 +xinerama
593 As above, except with core input from d1:
595 Xdmx :1 -display d0:0 -display d1:0 -input d1:0 +xinerama
598 As above, except with core input from a console window on the local
601 Xdmx :1 -display d0:0 -display d1:0 -input :0 +xinerama
604 As above, except with core input from the local keyboard and mouse:
606 Xdmx :1 -display d0:0 -display d1:0 -input local,kbd,ps2 +xinerama
608 Note that local input can be used under Linux while another X session is
609 running on :0 (assuming the user can access the Linux console tty and
610 mouse devices): a new (blank) VC will be used for keyboard input on the
611 local machine and the Ctrl-Alt-F* sequence will be available to change
612 to another VC (possibly back to another X session running on the local
613 machine). Using Ctrl-Alt-Backspace on the blank VC will terminate the
614 Xdmx session and return to the original VC.
616 This example uses the configuration file shown in the previous section:
618 Xdmx :1 -input :0 +xinerama -configfile filename -config example2
620 With this configuration file line:
622 option -input :0 +xinerama;
624 the command line can be shortened to:
626 Xdmx :1 -configfile filename -config example2
628 .SH "USING THE USB DEVICE DRIVERS"
630 The USB device drivers use the devices called
631 .IR /dev/input/event0 ", " /dev/input/event1 ", etc."
632 under Linux. These devices are driven using the
634 Linux kernel module, which is part of the hid suite. Please note that
639 Linux kernel modules, then USB devices will appear as core Linux input
640 devices and you will not be able to select between using the device only
645 XInput extension device. Further, you may be unable to unload the
647 Linux kernel module if
651 as an input device (this is quite helpful for laptop users and is set up
652 by default under some Linux distributions, but should be changed if USB
653 devices are to be used with
656 The USB device drivers search through the Linux devices for the first
657 mouse, keyboard, or non-mouse-non-keyboard Linux device and use that
659 .SH "KEYBOARD INITIALIZATION"
667 compiled to use the XKEYBOARD extension, then a keyboard on a backend or
668 console will be initialized using the map that the host X server
671 If the XKEYBOARD extension is used for both
673 and the host X server for the keyboard (i.e., the backend or console X
674 server), then the type of the keyboard will
675 be obtained from the host X server and the keyboard under
677 will be initialized with that information. Otherwise, the default type
678 of keyboard will be initialized. In both cases, the map from the host X
681 be used. This means that different initial behavior may be noted with
682 and without XKEYBOARD. Consistent and expected results will be obtained
683 by running XKEYBOARD on all servers and by avoiding the use of
685 on the backend or console X servers prior to starting
692 command line, then that map will currently be used for all keyboards.
693 .SH "MULTIPLE CORE KEYBOARDS"
694 X was not designed to support multiple core keyboards. However,
696 provides some support for multiple core keyboards. Best results will be
697 obtained if all of the keyboards are of the same type and are using the
698 same keyboard map. Because the X server passes raw key code information
699 to the X client, key symbols for keyboards with different key maps would
700 be different if the key code for each keyboard was sent without
701 translation to the client. Therefore,
703 will attempt to translate the key code from a core keyboard to the key
704 code for the key with the same key symbol of the
706 core keyboard that was loaded. If the key symbol appears in both maps,
707 the results will be expected. Otherwise, the second core keyboard will
708 return a NoSymbol key symbol for some keys that would have been
709 translated if it was the first core keyboard.
717 .BR DMX "(__libmansuffix__), " X "(__miscmansuffix__), "
718 .BR Xserver "(__appmansuffix__), " xdmxconfig "(__appmansuffix__), "
719 .BR vdltodmx "(__appmansuffix__), " xfs "(__appmansuffix__), "
720 .BR xkbcomp "(__appmansuffix__), " xkeyboard-config "(__miscmansuffix__)"
725 .I <dawes@xfree86.org>,
727 Rickard E. (Rik) Faith
728 .IR <faith@redhat.com> .
732 are based on code from The XFree86 Project
733 .RI ( http://www.xfree86.org )
735 .RI ( http://www.x.org ).