You can use the /proc filesystem interface to obtain run-time information about the driver, any installed NVIDIA graphics cards, and the AGP status.
This information is contained in several files in /proc/driver/nvidia
Lists the installed driver revision and the version of the GNU C compiler used to build the Linux kernel module.
The NVIDIA graphics driver tries to detect potential problems
with the host system's kernel and warns about them using the
kernel's printk() mechanism, typically logged by the system to
Important NVIDIA warning messages are also logged to dedicated text files in this /proc directory.
Provide information about each of the installed NVIDIA graphics adapters (model name, IRQ, BIOS version, Bus Type). Note that the BIOS version is only available while X is running.
Information about the installed AGP card's AGP capabilities.
Information about the host bridge (model and AGP capabilities).
The current AGP status. If AGP support has been enabled on your system, the AGP driver being used, the AGP rate, and information about the status of AGP Fast Writes and Side Band Addressing is shown.
The AGP driver is either NVIDIA (NVIDIA built-in AGP driver) or AGPGART (the Linux kernel's agpgart.o driver). If you see "inactive" next to AGPGART, then this means that the AGP chipset was programmed by AGPGART, but is not currently in use.
SBA and Fast Writes indicate whether either one of these features is currently in use. Note that several factors determine whether support for either will be enabled. Even if both the AGP card and the host bridge support them, the driver may decide not to use these features in favor of system stability. This is particularly true of AGP Fast Writes.