AGP(4)

📦
version 15.1 · 4 versions
, in freebsd 15.1, nixpkgs unstable

💅 agp(4) — the Kernel Interfaces Manual, bestie edition

okay so this is agp, aka the generic interface to the Accelerated Graphics Port (AGP), and I'm gonna walk you through it like we're texting at 2am 🫶 it's from the Kernel Interfaces Manual, and yes it's giving vintage.

✨ NAME ✨

agp — generic interface to the Accelerated Graphics Port (AGP). that's it, that's the whole vibe. a little bridge between your system and your graphics card, lowkey iconic 💅

✨ SYNOPSIS ✨

device agp

literally one line. she's effortless. ✨

💀 DEPRECATION NOTICE 💀

bestie, bad news 😭 the agp driver is slated to be removed in FreeBSD 16.0. it's giving "senior year, already got the diploma, just coasting" — enjoy it while it lasts, but don't build your whole future on it. fr fr.

🎀 DESCRIPTION 🎀

so the agp driver provides uniform, abstract methods for controlling the following devices. and when I say following, I mean the whole roster, no cap 👑

  • Ali: M1541, M1621 and M1671 host to AGP bridges
  • AMD: 751, 761 and 762 host to AGP bridges
  • ATI: RS100, RS200, RS250 and RS300 AGP bridges
  • Intel: i820, i840, i845, i850, and i860 host to AGP bridges
  • Intel: i810, i810-DC100, i810E, i815, 830M, 845G, 845M, 852GM, 852GME, 855GM, 855GME, 865G, 915G and 915GM SVGA controllers
  • Intel: 82443BX, 82443GX, 82443LX, 82815, 82820, 82830, 82840, 82845, 82845G, 82850, 82855, 82855GM, 82860, 82865, 82875P, E7205 and E7505 host to AGP bridges
  • NVIDIA: nForce and nForce2 AGP controllers
  • SiS: 530, 540, 550, 620, 630, 645, 645DX, 648, 650, 651, 655, 661, 730, 735, 740, 741, 745, 746, 760 and 5591 host to AGP bridges
  • VIA: 3296, 82C597, 82C598, 82C691, 82C694X, 82C8363, 8235, 8237, 8361, 8367, 8371, 8377, 8501, 8601, 862x, 8633, 8653, 8703, 8753, 8754, 8763, 8783, KT880, PM800, PM880, PN800, PN880, PT880, XM266 and XN266 host to PCI bridges

and like, the most common application of agp? it's for running X(7) (ports/x11/xorg-docs) on the Intel i81x controllers. that's the main character use case, iykyk 💖

🌈 IOCTLS 🌈

The following ioctl(2) operations can be performed on /dev/agpgart, which are defined in <sys/agpio.h>. buckle up bestie, there's a bunch 🦋

⭐ 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;

like a little ID card for your AGP system. so organized 💅

⭐ 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.

so if somebody else is holding it? EBUSY. it's occupied. take the hint 😭

⭐ 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.

not me telling you this is the "you're on your own" flag 🙈 the memory cleanup is your problem, bestie.

⭐ 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>. go off, mode bits 👑

⭐ 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   */
        uint32_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. hold onto that handle like it's your iced coffee 🍓

⭐ AGPIOC_DEALLOCATE

Free the previously allocated memory associated with the handle passed. bye bye memory, you served 💜

⭐ 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. yep, the same handle. keep track of it ✨

⭐ 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;

unbinding that memory, no drama, except EINVAL if there was nothing bound in the first place 😬

🦋 FILES 🦋

  • /dev/agpgart — AGP device node. that's the one, the special file, the portal 🌸

👀 SEE ALSO 👀

  • X(7) (ports/x11/xorg)

go read the docs, bestie, i believe in you 🫶

🧚 HISTORY 🧚

The agp driver first appeared in FreeBSD 4.1. a true elder, ancient and respected ✨👑

okay that's the whole page, mwah 💖 this was the AGP(4) manual on Debian, dated October 24, 2025. go forth and be so normal about AGP bridges. periodt. 🎀

📦 where this page comes from