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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=294792
B1nc0d3x <[email protected]> changed:
What |Removed |Added
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Attachment #270119|0 |1
is patch| |
--- Comment #1 from B1nc0d3x <[email protected]> ---
Comment on attachment 270119
--> https://bugs.freebsd.org/bugzilla/attachment.cgi?id=270119
drm(4) manpage
>.\"-
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>.Dd April 25, 2025
>.Dt DRM 4
>.Os
>.Sh NAME
>.Nm drm
>.Nd Direct Rendering Manager kernel interface
>.Sh SYNOPSIS
>.Cd "device drm2"
>.Sh DESCRIPTION
>The
>.Nm
>subsystem, implemented in
>.Fx
>as
>.Nm drm2 ,
>provides kernel support for hardware-accelerated graphics rendering.
>It is the kernel-side counterpart to the Direct Rendering Infrastructure
>.Pq DRI
>used by userspace graphics libraries such as Mesa.
>.Pp
>The
>.Nm
>subsystem manages access to the GPU on behalf of multiple processes,
>providing:
>.Bl -bullet
>.It
>Exclusive DRM master access for the compositor or X server, which
>controls modesetting and display configuration.
>.It
>Authenticated render-only access for unprivileged clients, which
>submit rendering workloads directly to the GPU without passing data
>through the master process.
>.It
>Graphics memory management via the Translation Table Manager
>.Pq TTM ,
>which handles allocation, eviction, and CPU/GPU mapping of buffer objects.
>.It
>Vertical blanking interrupt
>.Pq vblank
>tracking, used to synchronise page flips and rendering with the display
>refresh cycle.
>.It
>Kernel Mode Setting
>.Pq KMS ,
>which moves display configuration
>.Pq resolution, refresh rate, connector routing
>into the kernel so that it can be managed safely across context switches
>and VT changes.
>.El
>.Pp
>GPU-specific drivers (e.g., for Intel, AMD, or NVIDIA hardware) are
>built on top of the
>.Nm
>core and loaded as separate kernel modules.
>The
>.Nm
>core itself does not attach to any hardware directly.
>.Sh FILES
>Each GPU managed by
>.Nm
>is represented by a set of character devices under
>.Pa /dev/dri/ :
>.Bl -tag -width ".Pa /dev/dri/renderDN" -compact
>.It Pa /dev/dri/cardN
>Primary node.
>Used by the DRM master for modesetting and by authenticated clients
>for rendering.
>Accessible by members of the
>.Dq video
>group.
>.It Pa /dev/dri/renderDN
>Render node.
>Provides unprivileged, render-only access to the GPU without requiring
>DRM master authentication.
>.It Pa /dev/dri/controlDN
>Control node.
>Reserved for modesetting control; rarely used directly by applications.
>.El
>.Pp
>.Em N
>is the zero-based index of the GPU.
>.Pp
>Userspace DRI drivers are provided by the
>.Pa graphics/mesa-dri
>port and installed under
>.Pa /usr/local/lib/dri/ :
>.Bl -tag -width ".Pa /usr/local/lib/dri/swrast_dri.so" -compact
>.It Pa /usr/local/lib/dri/*_dri.so
>GPU-specific DRI driver modules loaded by Mesa at runtime.
>.El
>.Sh SYSCTL VARIABLES
>The
>.Nm
>subsystem exposes the following
>.Xr sysctl 8
>variables under the
>.Va hw.dri
>tree:
>.Bl -tag -width ".Va hw.dri.debug"
>.It Va hw.dri.debug
>Enable verbose debug output from the
>.Nm
>core.
>Set to a non-zero value to enable.
>Default is 0.
>.It Va hw.dri.notyet
>Log calls to unimplemented
>.Nm
>features.
>Default is 0.
>.It Va hw.dri.vblankoffdelay
>Delay in milliseconds before the vblank interrupt is automatically
>disabled when no clients are waiting on it.
>Default is 5000.
>.It Va hw.dri.timestamp_precision
>Maximum error, in microseconds, allowed in vblank and page-flip
>event timestamps.
>Default is 20.
>.It Va hw.dri.%d.name
>Name and version string of the GPU driver at index
>.Va %d .
>.It Va hw.dri.%d.vm
>Memory map information for the GPU at index
>.Va %d .
>.It Va hw.dri.%d.clients
>List of open clients for the GPU at index
>.Va %d .
>.It Va hw.dri.%d.bufs
>DMA buffer allocation information for the GPU at index
>.Va %d .
>.It Va hw.dri.%d.vblank
>Vblank counter and timing information for the GPU at index
>.Va %d .
>.El
>.Sh SEE ALSO
>.Xr agp 4 ,
>.Xr pci 4 ,
>.Xr vt 4 ,
>.Xr kldload 8 ,
>.Xr sysctl 8
>.Sh HISTORY
>The
>.Nm
>subsystem first appeared in
>.Fx 5.0 .
>The
>.Nm drm2
>rewrite, tracking the Linux DRM/KMS infrastructure, first appeared in
>.Fx 10.0 .
>.Sh AUTHORS
>.An -nosplit
>The
>.Nm
>core was written by
>.An Rickard E. Faith Aq Mt [email protected]
>and
>.An Gareth Hughes Aq Mt [email protected] .
>The
>.Fx
>port was maintained by
>.An Eric Anholt Aq Mt [email protected]
>and later by
>.An Jean-Sebastien Pedron Aq Mt [email protected] .
>This manual page was written by
>.An Kyle Crenshaw <b1nc0d3x> Aq Mt [email protected] .
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