<sect2>
<title>The Translation Table Manager (TTM)</title>
<para>
- TTM design background and information belongs here.
+ TTM design background and information belongs here.
</para>
<sect3>
- <title>TTM initialization</title>
+ <title>TTM initialization</title>
<warning><para>This section is outdated.</para></warning>
<para>
Drivers wishing to support TTM must fill out a drm_bo_driver
pointers for initializing the TTM, allocating and freeing memory,
waiting for command completion and fence synchronization, and memory
migration. See the radeon_ttm.c file for an example of usage.
- </para>
- <para>
- The ttm_global_reference structure is made up of several fields:
- </para>
- <programlisting>
- struct ttm_global_reference {
- enum ttm_global_types global_type;
- size_t size;
- void *object;
- int (*init) (struct ttm_global_reference *);
- void (*release) (struct ttm_global_reference *);
- };
- </programlisting>
- <para>
- There should be one global reference structure for your memory
- manager as a whole, and there will be others for each object
- created by the memory manager at runtime. Your global TTM should
- have a type of TTM_GLOBAL_TTM_MEM. The size field for the global
- object should be sizeof(struct ttm_mem_global), and the init and
- release hooks should point at your driver-specific init and
- release routines, which probably eventually call
- ttm_mem_global_init and ttm_mem_global_release, respectively.
- </para>
- <para>
- Once your global TTM accounting structure is set up and initialized
- by calling ttm_global_item_ref() on it,
- you need to create a buffer object TTM to
- provide a pool for buffer object allocation by clients and the
- kernel itself. The type of this object should be TTM_GLOBAL_TTM_BO,
- and its size should be sizeof(struct ttm_bo_global). Again,
- driver-specific init and release functions may be provided,
- likely eventually calling ttm_bo_global_init() and
- ttm_bo_global_release(), respectively. Also, like the previous
- object, ttm_global_item_ref() is used to create an initial reference
- count for the TTM, which will call your initialization function.
- </para>
+ </para>
+ The ttm_global_reference structure is made up of several fields:
+ </para>
+ struct ttm_global_reference {
+ enum ttm_global_types global_type;
+ size_t size;
+ void *object;
+ int (*init) (struct ttm_global_reference *);
+ void (*release) (struct ttm_global_reference *);
+ };
+ </programlisting>
+ There should be one global reference structure for your memory
+ manager as a whole, and there will be others for each object
+ created by the memory manager at runtime. Your global TTM should
+ have a type of TTM_GLOBAL_TTM_MEM. The size field for the global
+ object should be sizeof(struct ttm_mem_global), and the init and
+ release hooks should point at your driver-specific init and
+ release routines, which probably eventually call
+ ttm_mem_global_init and ttm_mem_global_release, respectively.
+ </para>
+ Once your global TTM accounting structure is set up and initialized
+ by calling ttm_global_item_ref() on it,
+ you need to create a buffer object TTM to
+ provide a pool for buffer object allocation by clients and the
+ kernel itself. The type of this object should be TTM_GLOBAL_TTM_BO,
+ and its size should be sizeof(struct ttm_bo_global). Again,
+ driver-specific init and release functions may be provided,
+ likely eventually calling ttm_bo_global_init() and
+ ttm_bo_global_release(), respectively. Also, like the previous
+ object, ttm_global_item_ref() is used to create an initial reference
+ count for the TTM, which will call your initialization function.
+ </para>
</sect3>
</sect2>
<sect2 id="drm-gem">
using driver-specific ioctls.
</para>
<para>
- On a fundamental level, GEM involves several operations:
- <itemizedlist>
- <listitem>Memory allocation and freeing</listitem>
- <listitem>Command execution</listitem>
- <listitem>Aperture management at command execution time</listitem>
- </itemizedlist>
- Buffer object allocation is relatively straightforward and largely
+ On a fundamental level, GEM involves several operations:
+ <itemizedlist>
+ <listitem>Memory allocation and freeing</listitem>
+ <listitem>Command execution</listitem>
+ <listitem>Aperture management at command execution time</listitem>
+ </itemizedlist>
+ Buffer object allocation is relatively straightforward and largely
provided by Linux's shmem layer, which provides memory to back each
object.
</para>
<para>
Device-specific operations, such as command execution, pinning, buffer
- read & write, mapping, and domain ownership transfers are left to
+ read & write, mapping, and domain ownership transfers are left to
driver-specific ioctls.
</para>
<sect3>
respectively. The conversion is handled by the DRM core without any
driver-specific support.
</para>
- <para>
- GEM also supports buffer sharing with dma-buf file descriptors through
- PRIME. GEM-based drivers must use the provided helpers functions to
- implement the exporting and importing correctly. See <xref linkend="drm-prime-support" />.
- Since sharing file descriptors is inherently more secure than the
- easily guessable and global GEM names it is the preferred buffer
- sharing mechanism. Sharing buffers through GEM names is only supported
- for legacy userspace. Furthermore PRIME also allows cross-device
- buffer sharing since it is based on dma-bufs.
- </para>
+ GEM also supports buffer sharing with dma-buf file descriptors through
+ PRIME. GEM-based drivers must use the provided helpers functions to
+ implement the exporting and importing correctly. See <xref linkend="drm-prime-support" />.
+ Since sharing file descriptors is inherently more secure than the
+ easily guessable and global GEM names it is the preferred buffer
+ sharing mechanism. Sharing buffers through GEM names is only supported
+ for legacy userspace. Furthermore PRIME also allows cross-device
+ buffer sharing since it is based on dma-bufs.
+ </para>
</sect3>
<sect3 id="drm-gem-objects-mapping">
<title>GEM Objects Mapping</title>
<sect3>
<title>Command Execution</title>
<para>
- Perhaps the most important GEM function for GPU devices is providing a
+ Perhaps the most important GEM function for GPU devices is providing a
command execution interface to clients. Client programs construct
command buffers containing references to previously allocated memory
objects, and then submit them to GEM. At that point, GEM takes care to
<title>GEM Function Reference</title>
!Edrivers/gpu/drm/drm_gem.c
</sect3>
- </sect2>
- <sect2>
- <title>VMA Offset Manager</title>
+ </sect2>
+ <sect2>
+ <title>VMA Offset Manager</title>
!Pdrivers/gpu/drm/drm_vma_manager.c vma offset manager
!Edrivers/gpu/drm/drm_vma_manager.c
!Iinclude/drm/drm_vma_manager.h
- </sect2>
- <sect2 id="drm-prime-support">
- <title>PRIME Buffer Sharing</title>
- PRIME is the cross device buffer sharing framework in drm, originally
- created for the OPTIMUS range of multi-gpu platforms. To userspace
- PRIME buffers are dma-buf based file descriptors.
- </para>
- <sect3>
- <title>Overview and Driver Interface</title>
- Similar to GEM global names, PRIME file descriptors are
- also used to share buffer objects across processes. They offer
- additional security: as file descriptors must be explicitly sent over
- UNIX domain sockets to be shared between applications, they can't be
- guessed like the globally unique GEM names.
- </para>
- Drivers that support the PRIME
- API must set the DRIVER_PRIME bit in the struct
- <structname>drm_driver</structname>
- <structfield>driver_features</structfield> field, and implement the
- <methodname>prime_handle_to_fd</methodname> and
- <methodname>prime_fd_to_handle</methodname> operations.
- </para>
- <synopsis>int (*prime_handle_to_fd)(struct drm_device *dev,
- struct drm_file *file_priv, uint32_t handle,
- uint32_t flags, int *prime_fd);
+ </sect2>
+ <sect2 id="drm-prime-support">
+ <title>PRIME Buffer Sharing</title>
+ <para>
+ PRIME is the cross device buffer sharing framework in drm, originally
+ created for the OPTIMUS range of multi-gpu platforms. To userspace
+ PRIME buffers are dma-buf based file descriptors.
+ </para>
+ <sect3>
+ <title>Overview and Driver Interface</title>
+ <para>
+ Similar to GEM global names, PRIME file descriptors are
+ also used to share buffer objects across processes. They offer
+ additional security: as file descriptors must be explicitly sent over
+ UNIX domain sockets to be shared between applications, they can't be
+ guessed like the globally unique GEM names.
+ </para>
+ <para>
+ Drivers that support the PRIME
+ API must set the DRIVER_PRIME bit in the struct
+ <structname>drm_driver</structname>
+ <structfield>driver_features</structfield> field, and implement the
+ <methodname>prime_handle_to_fd</methodname> and
+ <methodname>prime_fd_to_handle</methodname> operations.
+ </para>
+ <para>
+ <synopsis>int (*prime_handle_to_fd)(struct drm_device *dev,
+ struct drm_file *file_priv, uint32_t handle,
+ uint32_t flags, int *prime_fd);
int (*prime_fd_to_handle)(struct drm_device *dev,
- struct drm_file *file_priv, int prime_fd,
- uint32_t *handle);</synopsis>
- Those two operations convert a handle to a PRIME file descriptor and
- vice versa. Drivers must use the kernel dma-buf buffer sharing framework
- to manage the PRIME file descriptors. Similar to the mode setting
- API PRIME is agnostic to the underlying buffer object manager, as
- long as handles are 32bit unsigned integers.
- </para>
- <para>
- While non-GEM drivers must implement the operations themselves, GEM
- drivers must use the <function>drm_gem_prime_handle_to_fd</function>
- and <function>drm_gem_prime_fd_to_handle</function> helper functions.
- Those helpers rely on the driver
- <methodname>gem_prime_export</methodname> and
- <methodname>gem_prime_import</methodname> operations to create a dma-buf
- instance from a GEM object (dma-buf exporter role) and to create a GEM
- object from a dma-buf instance (dma-buf importer role).
- </para>
- <para>
- <synopsis>struct dma_buf * (*gem_prime_export)(struct drm_device *dev,
- struct drm_gem_object *obj,
- int flags);
+ struct drm_file *file_priv, int prime_fd,
+ uint32_t *handle);</synopsis>
+ Those two operations convert a handle to a PRIME file descriptor and
+ vice versa. Drivers must use the kernel dma-buf buffer sharing framework
+ to manage the PRIME file descriptors. Similar to the mode setting
+ API PRIME is agnostic to the underlying buffer object manager, as
+ long as handles are 32bit unsigned integers.
+ </para>
+ While non-GEM drivers must implement the operations themselves, GEM
+ drivers must use the <function>drm_gem_prime_handle_to_fd</function>
+ and <function>drm_gem_prime_fd_to_handle</function> helper functions.
+ Those helpers rely on the driver
+ <methodname>gem_prime_export</methodname> and
+ <methodname>gem_prime_import</methodname> operations to create a dma-buf
+ instance from a GEM object (dma-buf exporter role) and to create a GEM
+ object from a dma-buf instance (dma-buf importer role).
+ </para>
+ <synopsis>struct dma_buf * (*gem_prime_export)(struct drm_device *dev,
+ struct drm_gem_object *obj,
+ int flags);
struct drm_gem_object * (*gem_prime_import)(struct drm_device *dev,
- struct dma_buf *dma_buf);</synopsis>
- These two operations are mandatory for GEM drivers that support
- PRIME.
- </para>
- </sect3>
- <sect3>
- <title>PRIME Helper Functions</title>
-!Pdrivers/gpu/drm/drm_prime.c PRIME Helpers
+ struct dma_buf *dma_buf);</synopsis>
+ These two operations are mandatory for GEM drivers that support
+ PRIME.
+ </para>
</sect3>
- </sect2>
- <sect2>
- <title>PRIME Function References</title>
+ <sect3>
+ <title>PRIME Helper Functions</title>
+!Pdrivers/gpu/drm/drm_prime.c PRIME Helpers
+ </sect3>
+ </sect2>
+ <sect2>
+ <title>PRIME Function References</title>
!Edrivers/gpu/drm/drm_prime.c
- </sect2>
- <sect2>
- <title>DRM MM Range Allocator</title>
- <sect3>
- <title>Overview</title>
+ </sect2>
+ <sect2>
+ <title>DRM MM Range Allocator</title>
+ <sect3>
+ <title>Overview</title>
!Pdrivers/gpu/drm/drm_mm.c Overview
- </sect3>
- <sect3>
- <title>LRU Scan/Eviction Support</title>
+ </sect3>
+ <sect3>
+ <title>LRU Scan/Eviction Support</title>
!Pdrivers/gpu/drm/drm_mm.c lru scan roaster
- </sect3>
+ </sect3>
</sect2>
- <sect2>
- <title>DRM MM Range Allocator Function References</title>
+ <sect2>
+ <title>DRM MM Range Allocator Function References</title>
!Edrivers/gpu/drm/drm_mm.c
!Iinclude/drm/drm_mm.h
- </sect2>
+ </sect2>
</sect1>
<!-- Internals: mode setting -->
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