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.Dd December 11, 2021
.Dt VCHIQ 4
.Os
.Sh NAME
.Nm vchiq
.Nd Broadcom VideoCore Host Interface device driver
.Sh SYNOPSIS
.Cd "vchiq* at simplebus?"
.Cd "vchiq* at acpi?"
.Sh DESCRIPTION
The
.Nm
driver provides support for the VideoCore 4 GPU messaging interface in
Broadcom SoCs found in boards such as the Raspberry Pi.
.Pp
Libraries in pkgsrc provide OpenGL ES support and video decoding acceleration
for the VideoCore 4 using the
.Pa /dev/vchiq
interface exposed to userland.
.Pp
Audio output support is provided by the kernel through
.Xr vcaudio 4 ,
which uses this messaging interface to the GPU internally.
.Pp
Debugging information may be obtained reading the device with
.Xr cat 1 .
eg:
.Dl cat /dev/vchiq
.Pp
Information such as slots and usage by particular functions of the VideoCore 4
device are displayed.
.Sh SEE ALSO
.Xr cat 1 ,
.Xr acpi 4 ,
.Xr bcmgpio 4 ,
.Xr vcaudio 4 ,
.Pa pkgsrc/misc/raspberrypi-userland ,
.Pa pkgsrc/multimedia/omxplayer
.Sh HISTORY
The
.Nm
device driver appeared in
.Nx 7.0 .
.Sh BUGS
.Pa /dev/vchiq
does not follow the standard model for graphical acceleration on Unix-like
systems, so applications have to be specially built to take advantage of it.
The interface to userland also cannot be exposed by 64-bit or big endian
kernels due to problems in the upstream Broadcom code.