AGP(4) BSD Kernel Interfaces Manual AGP(4)NAMEagp — accelerated graphics port driver
SYNOPSIS
agp* at pchb?
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 graph‐
ics 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 host-to-AGP bridge
- AMD 751 and 761 host-to-AGP bridges
- Intel 82810, 82810-DC100, 82810E, and 82815 SVGA controllers
- SiS 5591 host-to-AGP bridge
- VIA
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. The calls supported are:
AGPIOC_INFO
Get AGP information, setting the members in the agp_info struc‐
ture as defined in <sys/agpio.h>:
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 AGP.
AGPIOC_RELEASE
Release AGP.
AGPIOC_SETUP
Set up AGP, using the members in the agp_setup structure as
defined in <sys/agpio.h>:
typedef struct _agp_setup {
uint32_t agp_mode; /* mode info of bridge */
} agp_setup;
AGPIOC_ALLOCATE
Allocate AGP space, using and setting the members in the
agp_allocate structure as defined in <sys/agpio.h>:
typedef struct _agp_allocate {
int key; /* tag of allocation */
size_t pg_count; /* number of pages */
uint32_t type; /* 0 == normal, other devspec */
uint32_t physical; /* device specific (some devices
* need a phys address of the
* actual page behind the gatt
* table) */
} agp_allocate;
AGPIOC_DEALLOCATE
Deallocate AGP space.
AGPIOC_BIND
Bind AGP space, using the members in the agp_bind structure as
defined in <sys/agpio.h>:
typedef struct _agp_bind {
int key; /* tag of allocation */
off_t pg_start; /* starting page to populate */
} agp_bind;
AGPIOC_UNBIND
Unbind AGP space, using the members in the agp_unbind structure
as defined in <sys/agpio.h>:
typedef struct _agp_unbind {
int key; /* tag of allocation */
uint32_t priority; /* priority for paging out */
} agp_unbind;
FILES
/dev/agp? AGP GART device special files
/dev/agpgart AGP GART device special file
EXAMPLES
This short code fragment is an example of opening the AGP device and per‐
forming some basic operations:
#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/agp0", 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 ALSOioctl(2), pci(4)HISTORY
The agp driver first appeared in FreeBSD 4.1. It was adopted in
NetBSD 1.6.
BSD October 3, 2010 BSD
