One of the most useful tools for diagnosing problems is the X log file in /var/log. Lines that begin with (II) are information, (WW) are warnings, and (EE) are errors. You should make sure that the correct config file (i.e. the config file you are editing) is being used; look for the line that begins with:

    (==) Using config file:

Also make sure that the NVIDIA driver is being used, rather than the “nv” or “vesa” driver. Search for

    (II) LoadModule: "nvidia"

Lines from the driver should begin with:

    (II) NVIDIA(0)

By default, the NVIDIA X driver prints relatively few messages to stderr and the X log file. If you need to troubleshoot, then it may be helpful to enable more verbose output by using the X command line options -verbose and -logverbose, which can be used to set the verbosity level for the stderr and log file messages, respectively. The NVIDIA X driver will output more messages when the verbosity level is at or above 5 (X defaults to verbosity level 1 for stderr and level 3 for the log file). So, to enable verbose messaging from the NVIDIA X driver to both the log file and stderr, you could start X with the verbosity level set to 5, by doing the following

    % startx -- -verbose 5 -logverbose 5

No, the NVIDIA FreeBSD Graphics Driver is a native driver. It does provide Linux OpenGL libraries in addition to the native, FreeBSD libraries to enable users to run Linux OpenGL applications.

This release is thread-safe on FreeBSD 7.3 or later systems making use of the libpthread or libthr KSE threading libraries. On these systems, the NVIDIA Linux ABI compatibility libraries are fully thread-safe as well.

The Linux compatibility libraries are not able to correctly determine if they are used in a multithreaded application because the %gs segment register is not initialized correctly for Linux compatibility.

The __GL_SINGLE_THREADED environment variable (set to "1") can be used to work around this issue, but at the cost of thread-safeness.

When measuring any application's memory usage, you must be careful to distinguish between physical system RAM used and virtual mappings of shared resources. For example, most shared libraries exist only once in physical memory but are mapped into multiple processes. This memory should only be counted once when computing total memory usage. In the same way, the video memory on a graphics card or register memory on any device can be mapped into multiple processes. These mappings do not consume normal system RAM.

This has been a frequently discussed topic on XFree86 mailing lists; see, for example:

http://marc.theaimsgroup.com/?l=xfree-xpert&m=96835767116567&w=2

Note, also, that X must allocate resources on behalf of X clients (the window manager, your web browser, etc); the X server's memory usage will increase as more clients request resources such as pixmaps, and decrease as you close X applications.

The IndirectMemoryAccess X configuration option may cause additional virtual address space to be reserved.

The NVIDIA driver does not support the graphics component of the XFree86-DGA (Direct Graphics Access) extension. Applications can use the XDGASelectInput() function to acquire relative pointer motion, but graphics-related functions such as XDGASetMode() and XDGAOpenFramebuffer() will fail.

The graphics component of XFree86-DGA is not supported because it requires a CPU mapping of framebuffer memory. As graphics cards ship with increasing quantities of video memory, the NVIDIA X driver has had to switch to a more dynamic memory mapping scheme that is incompatible with DGA. Furthermore, DGA does not cooperate with other graphics rendering libraries such as Xlib and OpenGL because it accesses GPU resources directly.

NVIDIA recommends that applications use OpenGL or Xlib, rather than DGA, for graphics rendering. Using rendering libraries other than DGA will yield better performance and improve interoperability with other X applications.

"Xid" messages indicate that a general GPU error occurred, most often due to the driver misprogramming the GPU or to corruption of the commands sent to the GPU. These messages provide diagnostic information that can be used by NVIDIA to aid in debugging reported problems.

Clock frequency settings are not saved/restored automatically by default to avoid potential stability and other problems that may be encountered if the chosen frequency settings differ from the defaults qualified by the manufacturer. You can use the command line below in ~/.xinitrc to automatically apply custom clock frequency settings when the X server is started:

    # nvidia-settings -a GPUOverclockingState=1 -a GPU2DClockFreqs=<GPU>,<MEM> -a GPU3DClockFreqs=<GPU>,<MEM>

Here <GPU> and <MEM> are the desired GPU and video memory frequencies (in MHz), respectively.

The XRandR X extension is not presently aware of multiple display devices on a single X screen; it only sees the MetaMode bounding box, which may contain one or more actual modes. This means that if multiple MetaModes have the same bounding box, XRandR will not be able to distinguish between them.

In order to support DynamicTwinView, the NVIDIA X driver must make each MetaMode appear to be unique to XRandR. Presently, the NVIDIA X driver accomplishes this by using the refresh rate as a unique identifier.

You can use `nvidia-settings -q RefreshRate` to query the actual refresh rate on each display device.

This behavior can be disabled by setting the X configuration option "DynamicTwinView" to FALSE.

For details, see Chapter 11, Configuring Multiple Display Devices on One X Screen.

If your X config file has a Module section that does not list the "extmod" module, some X server extensions may be missing, resulting in error messages of the form:

Xlib: extension "SHAPE" missing on display ":0.0"
Xlib: extension "XFree86-VidModeExtension" missing on display ":0.0"
Xlib: extension "XFree86-DGA" missing on display ":0.0"

You can solve this problem by adding the line below to your X config file's Module section:

    Load "extmod"

Please visit ftp://download.nvidia.com/XFree86/FreeBSD-x86_64/ (new packages for FreeBSD 7.3 and newer) or ftp://download.nvidia.com/freebsd/ (old i386-only packages for FreeBSD 5.3 through 7.2, inclusive).

Different tools have different formats for the PCI Bus ID of a PCI device.

The X server's "BusID" X configuration file option interprets the BusID string in the format "bus@domain:device:function" (the "@domain" portion is only needed if the PCI domain is non-zero), in decimal. More specifically,

"%d@%d:%d:%d", bus, domain, device, function

in printf(3) syntax. NVIDIA X driver logging, nvidia-xconfig, and nvidia-settings match the X configuration file BusID convention.

The FreeBSD pciconf(8) utility, in contrast, prints and interprets the PCI Bus ID in the format "domain:bus:device.function" (the "domain:" portion is only needed if the PCI domain is non-zero), in decimal. More specifically,

"pci%d:%d:%d:%d", domain, bus, device, function

in printf(3) syntax.

X server version numbers can be difficult to interpret because some X.Org X servers report the versions of different things.

In 2003, X.Org created a fork of the XFree86 project's code base, which used a monolithic build system to build the X server, libraries, and applications together in one source code repository. It resumed the release version numbering where it left off in 2001, continuing with 6.7, 6.8, etc., for the releases of this large bundle of code. These version numbers are sometimes written X11R6.7, X11R6.8, etc. to include the version of the X protocol.

In 2005, an effort was made to split the monolithic code base into separate modules with their own version numbers to make them easier to maintain and so that they could be released independently. X.Org still occasionally releases these modules together, with a single version number. These releases are simply referred to as “X.Org releases”, or sometimes “katamari” releases. For example, X.Org 7.6 was released on December 20, 2010 and contains version 1.9.3 of the xorg-server package, which contains the core X server itself.

The release management changes from XFree86, to X.Org monolithic releases, to X.Org modular releases impacted the behavior of the X server's -version command line option. For example, XFree86 X servers always report the version of the XFree86 monolithic package:

XFree86 Version 4.3.0 (Red Hat Linux release: 4.3.0-2)
Release Date: 27 February 2003
X Protocol Version 11, Revision 0, Release 6.6

X servers in X.Org monolithic and early “katamari” releases did something similar:

X Window System Version 7.1.1
Release Date: 12 May 2006
X Protocol Version 11, Revision 0, Release 7.1.1

However, X.Org later modified the X server to start printing its individual module version number instead:

X.Org X Server 1.9.3
Release Date: 2010-12-13
X Protocol Version 11, Revision 0

Please keep this in mind when comparing X server versions: what looks like “version 7.x” is older than version 1.x.

Prior to the 302.* driver series, the list of modes reported to applications by the NVIDIA X driver was not limited to the list of modes natively supported by a display device. In order to expose the largest possible set of modes on digital flat panel displays, which typically do not accept arbitrary mode timings, the driver maintained separate sets of "front-end" and "back-end" mode timings, and scaled between them to simulate the availability of more modes than would otherwise be supported.

Front-end timings were the values reported to applications, and back-end timings were what was actually sent to the display. Both sets of timings went through the full mode validation process, with the back-end timings having the additional constraint that they must be provided by the display's EDID, as only EDID-provided modes can be safely assumed to be supported by the display hardware. Applications could request any available front-end timings, which the driver would implicitly scale to either the "best fit" or "native" mode timings. For example, an application might request an 800x600 @ 60 Hz mode and the driver would provide it, but the real mode sent to the display would be 1920x1080 @ 30 Hz. While the availability of modes beyond those natively supported by a display was convenient for some uses, it created several problems. For example:

Version 1.2 of the X Resize and Rotate extension (henceforth referred to as "RandR 1.2") allows configuration of display scaling in a much more flexible and standardized way. The protocol allows applications to choose exactly which (back-end) mode timing is used, and exactly how the screen is scaled to fill that mode. It also allows explicit control over which displays are enabled, and which portions of the screen they display. This also provides much-needed transparency: the mode timings reported by RandR 1.2 are the actual mode timings being sent to the display. However, this means that only modes actually supported by the display are reported in the RandR 1.2 mode list. Scaling configurations, such as the 800x600 to 1920x1080 example above, need to be configured via the RandR 1.2 transform feature. Adding implicitly scaled modes to the mode list would conflict with the transform configuration options and reintroduce the same problems that the previous front-end/back-end timing system had.

With the introduction of RandR 1.2 support to the 302.* driver series, the front-end/back-end timing system was abandoned, and the list of mode timings exposed by the NVIDIA X driver was simplified to include only those modes which would actually be driven by the hardware. Although it remained possible to manually configure all of the scaling configurations that were previously possible, and many scaling configurations which were previously impossible, this change resulted in some inconvenient losses of functionality:

Subsequent driver releases restored some of this functionality without reverting to the front-end/back-end system:

As mentioned previously, the RandR 1.2 mode list contains only modes which are supported by the display. Modern applications that wish to set modes other than those available in the RandR 1.2 mode list are encouraged to use RandR 1.2 transformations to program any required scaling operations. For example, the xrandr utility can program RandR scaling transformations, and the following command can scale a 1280x720 mode to a display connected to output DVI-I-0 that does not support the desired mode, but does support 1920x1080:

xrandr --output DVI-I-0 --mode 1920x1080 --scale-from 1280x720