xvfb: function, availability and HP support status

[Gerard Moroney]

Hi,

Can someone please explain to me under what circumstances xvfb is required ? If you do not have an appropriate monitor, can Xserver be configured to render to a graphics card ( I assme it can)? From the note above, it appears that xvfb is now officially supported by HP. Can someone pleae point me towards the location of the appropriate documentation and patches ?

[Marcin Wicinski · Accepted solution]

Description of the X Server

The X Windows System (commonly referred to as "X", or "X11") uses a client-server model for communication, where the X server is the process which controls the display, and each client process in turn communicates with the X server to draw one or more windows to the screen.

Many different varieties of X server exist. The most common ones in use are the general-purpose X servers, which include the /usr/bin/X11/X binary on HP-UX (and most other UNIX) systems, the controlling processes on Xterminals, and a number of PC-based X emulators (ie Reflection/X and eXceed to name a few). Each of these "general-purpose" X servers is designed to render to a graphics device and receive input from a keyboard device and a pointer device (usually a mouse or trackball). However, several other "special-purpose" X servers exist, including Xnest (which renders to a window, allowing multiple copies of the X server to run on one screen), the X Print Server (also known as TPS, which renders to a printer device), and Xvfb (which renders to a region of memory).

When Xvfb is appropriate
The Xvfb (X Virtual Frame Buffer) server is well-suited for systems that run certain classes of applications. It turns out that one of the less well-known features of the X server is that it is capable of rendering to a region of memory in lieu of the graphics screen, and a number of applications utilize these features in order to render graphics (ie, to submit to a web page).

The Xvfb server is NOT appropriate for situations where a user is attempting to display an application to a remote system. If a user is attempting to display X applications remotely.

Installation

The following sequence of commands will install Xvfb on a 10.20 system. Installation for an 11.00 system is identical except for the filename:

# cd /tmp
# gunzip Xvfb.depot.gz
# swinstall -s /tmp/Xvfb.depot \*

How to configure and test the Xvfb server
The Xvfb installation creates a configuration file, /etc/rc.config.d/xvfb. Two configuration variables are found in this file, XVFB_START and XVFB_DISPLAY:

XVFB_START: When this is set to 1, then the Xvfb server will start at boot time.
XVFB_DISPLAY: This is the display number the Xvfb server will use; in most cases the default value of 0 will suffice. If the system is running another X server, then this value may need to be incremented. If this value is changed, then the value of the DISPLAY used in application programs will change to hostname:XVFB_DISPLAY instead of hostname:0.
The Xvfb server also requires the X Font Server to be configured. In order to configure the X Font Server, xfs, simply edit the file /etc/rc.config.d/xfs and ensure that the variable RUN_X_FONT_SERVER is set to 1. Start the X font server with the command:

# /sbin/init.d/xfs start


In order to start and test the Xvfb server, simply run the following commands:

# /sbin/init.d/xvfb start
# export DISPLAY=hostname:0
# xdpyinfo
name of display: hostname:0.0
version number: 11.0
vendor string: X Consortium
.
.
.

[Marcin Wicinski]

Hi,

one more: check following patches

PHSS_23546 (11.xx) or PHSS_23535 (10.20)


later,

[LBertoglio]

Hi,

where can i download Xvfb sw depot? It is not in hprc.external.hp.com (graphic/graphic), nor it is installed with PHSS_23546.
Thanks.

[Alex Glennie]

Gerard, you have this already .... I sent it in my earlier email.

but for LBertoglio

Xvfb is typically delivered in some implementations as a separate
program in the same directory as the normal X server, e.g.
/usr/bin/X11/Xvfb. HP's implementation differs, however, as the
functionality of both the video and Xvfb servers are delivered in the
single program /usr/bin/X11/X.

There are 4 steps required to get Xvfb up and running on HP-UX:
1) install the appropriate X server patches, if necessary,
2) configure the Xvfb server,
3) run the Xvfb server,
4) run X client programs connected to the Xvfb server.

Installing the X server patches
-------------------------------
Xvfb server functionality was first delivered on HP-UX in the June 2001
Xserver patches:
10.20 PHSS_23535
11.0 PHSS_23546
11i PHSS_21816
If your X server was installed and/or patched prior to June 2001 you
will need to apply the appropriate patch from the above list (or any
superceding patches). You can confirm whether your X server supports
the Xvfb functionality by doing:
man Xserver
and searching for the section titled "XVFB OPTIONS".

If you need more detailed instructions post me your email address

[Syed Ali_1]

Hi Alex,

Could you please send the detailed instructions to sma@avs.com as well?

Thanks,

Syed

[Matt Gong]

Please mail the detailed instructions to me too. Or post here so others may view it.

I've installed the PHSS_23546 patch for 11.00, and I still don't know what to do, since I've tried "man Xserver" and no XVFB shows up anywhere.

Thanks in advance

-Matt Gong