AGP(4)

NAME
agp - accelerated graphics port driver

SYNOPSIS
To compile this driver into the kernel, place the following lines in your kernel configuration file:

device agp

Alternatively, to load the driver as a module at boot time, place the following line in loader.conf(5):

    agp_load="YES"

DESCRIPTION
The agp driver provides machine-independent support for the accelerated graphics port (AGP) found on many PC-based and PCI systems. The AGP specification was designed by Intel.

The AGP chipset is positioned between the PCI-Host bridge and the graphics accelerator to provide a high-performance dedicated graphics bus for moving large amounts of data directly from host memory to the graphics accelerator. The specification currently supports a peak bandwidth of 528 MB/s. AGP uses a Graphics Address Remapping Table (GART) to provide a physically-contiguous view of scattered pages in host memory for DMA transfers.

The agp driver supports the following chipsets:

-   ALI M1541, M1621 and M1671 host to AGP bridges
-   AMD 751, 761 and 762 host to AGP bridges
-   AMD 8151 AGP graphics tunnel
-   ATI RS100, RS200, RS250 and RS300 AGP bridges
-   Intel i810, i815, i830, 845, 852, 855, 865, 915, 945, 946 and 965 series SVGA controllers
-   Intel 82443LX, 82443BX, 82443GX, i820, i840, i845, i845G, i850, i855, i855GM, i860, i865, i875P, E7205 and E7505 host to AGP bridges
-   Nvidia nForce, nForce2 and nForce3 AGP controllers
-   SiS 530, 540, 550, 620, 630, 645, 645DX, 648, 650, 651, 655, 661, 730, 735, 740, 741, 745, 746, 755, 760 and 5591 host to AGP bridges
-   ULi M1689 AGP controller
-   VIa 3238, 3296, 82C597, 82C598, 82C691, 82C694X, 82C8363, 8235, 8237, 8361, 8367, 8371, 8377, 8380, 8385, 8501, 8601, 862x, 8633, 8653, 8703, 8753, 8754, 8763, 8783, KT880, K8T800Pro, PM800, PM880, PN800, PN880, PT880, XM266 and XN266 host to PCI bridges

The agp driver also provides an interface to user processes for use by X servers. A user process communicates to the device initially by means of ioctl(2) calls performed on /dev/agpgart. All calls and related structures are defined in <sys/agpio.h>. The calls supported are:

AGPIOC_INFO
    Returns state of the agp system. The result is a pointer to the following structure:

        typedef struct _agp_info {
                agp_version version;    /* version of the driver       */
                uint32_t bridge_id;     /* bridge vendor/device        */
                uint32_t agp_mode;      /* mode info of bridge         */
                off_t aper_base;        /* base of aperture            */
                size_t aper_size;       /* size of aperture            */
                size_t pg_total;        /* max pages (swap + system)   */
                size_t pg_system;       /* max pages (system)          */
                size_t pg_used;         /* current pages used          */
        } agp_info;

AGPIOC_ACQUIRE
    Acquire control of the AGP chipset for use by this client. Returns EBUSY if the AGP chipset is already acquired by another client.

AGPIOC_RELEASE
    Release control of the AGP chipset. This does not unbind or free any allocated memory, which is the responsibility of the client to handle if necessary.

AGPIOC_SETUP
    Enable the AGP hardware with the relevant mode. This ioctl(2) takes the following structure:

        typedef struct _agp_setup {
                uint32_t agp_mode;     /* mode info of bridge          */
        } agp_setup;

    The mode bits are defined in <sys/agpio.h>.

AGPIOC_ALLOCATE
    Allocate physical memory suitable for mapping into the AGP aperture. This ioctl(2) takes the following structure:

        typedef struct _agp_allocate {
                int key;               /* tag of allocation            */
                size_t pg_count;       /* number of pages              */
                uint32_t type;         /* 0 == normal, other devspec   */
                paddr_t physical;      /* device specific (some devices
                                        * need a phys address of the
                                        * actual page behind the gatt
                                        * table)                       */
        } agp_allocate;

    Returns a handle to the allocated memory.

AGPIOC_DEALLOCATE
    Free the previously allocated memory associated with the handle passed.

AGPIOC_BIND
    Bind the allocated memory at given offset with the AGP aperture. Returns EINVAL if the memory is already bound or the offset is not at AGP page boundary. This ioctl(2) takes the following structure:

        typedef struct _agp_bind {
                int key;               /* tag of allocation            */
                off_t pg_start;        /* starting page to populate    */
        } agp_bind;

    The tag of allocation is the handle returned by AGPIOC_ALLOCATE.

AGPIOC_UNBIND
    Unbind memory from the AGP aperture. Returns EINVAL if the memory is not bound. This ioctl(2) takes the following structure:

        typedef struct _agp_unbind {
                int key;               /* tag of allocation            */
                uint32_t priority;     /* priority for paging out      */
        } agp_unbind;

FILES
/dev/agpgart
    AGP GART device special file

EXAMPLES
This short code fragment is an example of opening the AGP device and performing some basic operations:

    #include stdio.h
    #include sys/types.h
    #include sys/ioctl.h
    #include sys/agpio.h
    #include fcntl.h
    #include err.h
    int
    main(int argc, char **argv)
    {
    	int fd;
    	agp_info info;
    	agp_allocate alloc;
    	agp_setup setup;
    	agp_bind bind;
    	agp_unbind unbind;
    	fd = open("/dev/agpgart", O_RDWR);
    	if (fd  0)
    		err(1, "open");
    	if (ioctl(fd, AGPIOC_INFO, info)  0)
    		err(2, "ioctl AGPIOC_INFO");
    	printf("version:	%u.%u\n", info.version.major,
    	    info.version.minor);
    	printf("id:		%x\n", info.bridge_id);
    	printf("mode:		%x\n", info.agp_mode);
    	printf("base:		%x\n", info.aper_base);
    	printf("size:		%uM\n", info.aper_size);
    	printf("total mem:	%u\n", info.pg_total);
    	printf("system mem:	%u\n", info.pg_system);
    	printf("used mem:	%u\n\n", info.pg_used);
    	setup.agp_mode = info.agp_mode;
    	if (ioctl(fd, AGPIOC_SETUP, setup)  0)
    		err(3, "ioctl AGPIOC_SETUP");
    	if (ioctl(fd, AGPIOC_ACQUIRE, 0)  0)
    		err(3, "ioctl AGPIOC_ACQUIRE");
    	alloc.type = 0;
    	alloc.pg_count = 64;
    	if (ioctl(fd, AGPIOC_ALLOCATE, alloc)  0)
    		err(4, "ioctl AGPIOC_ALLOCATE");
    	printf("alloc key %d, paddr %x\n", alloc.key, alloc.physical);
    	if (ioctl(fd, AGPIOC_INFO, info)  0)
    		err(5, "ioctl AGPIOC_INFO");
    	bind.key = alloc.key;
    	bind.pg_start = 0x1000;
    	if (ioctl(fd, AGPIOC_BIND, bind)  0)
    		err(6, "ioctl AGPIOC_BIND");
    	printf("used mem now:	%u\n\n", info.pg_used);
    	unbind.key = alloc.key;
    	unbind.priority = 0;
    	if (ioctl(fd, AGPIOC_UNBIND, unbind)  0)
    		err(6, "ioctl AGPIOC_BIND");
    	if (ioctl(fd, AGPIOC_DEALLOCATE, alloc.key)  0)
    		err(6, "ioctl AGPIOC_DEALLOCATE");
    	if (ioctl(fd, AGPIOC_RELEASE, 0)  0)
    		err(7, "ioctl AGPIOC_RELEASE");
    	close(fd);
    	printf("agp test successful\n");
    	return 0;
    }

SEE ALSO
ioctl(2)

HISTORY
The agp driver first appeared in FreeBSD 4.1.