AGP(4)

💖 agp — the whole vibe 💖

okay bestie, welcome to the agp manual page, section 4 of the Kernel Interfaces Manual, and no I will not be normal about it. this is the generic interface to the Accelerated Graphics Port (AGP). yes. AGP. the slot your graphics card used to live in before PCIe made everyone forget. iconic behavior, honestly. 🎀

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✨ NAME ✨

agp — generic interface to the Accelerated Graphics Port (AGP). that's it. that's the name. short, sweet, ate. 💅

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🌸 SYNOPSIS 🌸

device agp

just one line. put it in your kernel config and the whole thing wakes up. slay.

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🦋 DESCRIPTION 🦋

okay so here's the tea: the agp driver gives you uniform, abstract methods for controlling a whole squad of devices. and when I say squad, I mean squad. here's everybody invited to the party:

• 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

the most common application of agp is for running X(7) on the Intel i81x controllers. that's the one everybody actually shows up for. 💜

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👑 IOCTLS 👑

so the following ioctl(2) operations can be performed on /dev/agpgart, and they're defined in <sys/agpio.h>. buckle up, there's a struct for basically each one. 🙈

• 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. like, someone else is already holding the aux cord, bestie. 😭
• 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. heads up: releasing ≠ cleaning up. that's on you. 💀
• 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   */
        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. that handle is your receipt, keep it safe. 🧚

• 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;

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🍓 FILES 🍓

• /dev/agpgart — AGP device node. the main character of this entire page, lowkey. ✨

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🌈 SEE ALSO 🌈

• X(7) (ports/x11/xorg)

go read that one next, bestie, it's the whole reason any of this matters. 🫶

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⭐ HISTORY ⭐

The agp driver first appeared in FreeBSD 4.1. a legend was born. 💫

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and that's the page!! this one came from the good people at Debian, dated November 28, 2007 — so yeah, vintage. antique, even. but we still stan. bye bestie, go forth and ioctl responsibly 💖✨🎀