[PATCH mesa 4/7] Add the EGL_MESA_configless_context extension
Neil Roberts
neil at linux.intel.com
Fri Mar 7 10:05:47 PST 2014
This extension provides a way for an application to render to multiple
surfaces with different buffer formats without having to use multiple
contexts. An EGLContext can be created without an EGLConfig by passing
EGL_NO_CONFIG_MESA. In that case there are no restrictions on the surfaces
that can be used with the context apart from that they must be using the same
EGLDisplay.
_mesa_initialze_context can now take a NULL gl_config which will mark the
context as ‘configless’. It will memset the visual to zero in that case.
Previously the i965 and i915 drivers were explicitly creating a zeroed visual
whenever 0 is passed for the EGLConfig. Mesa needs to be aware that the
context is configless because it affects the initial value to use for
glDrawBuffer. The first time the context is bound it will set the initial
value for configless contexts depending on whether the framebuffer used is
double-buffered.
---
docs/specs/MESA_configless_context.spec | 120 ++++++++++++++++++++++++++++++
include/EGL/eglext.h | 5 ++
src/egl/drivers/dri2/egl_dri2.c | 1 +
src/egl/main/eglapi.c | 2 +-
src/egl/main/eglcontext.c | 20 ++++-
src/egl/main/egldisplay.h | 1 +
src/egl/main/eglmisc.c | 1 +
src/mesa/drivers/dri/i915/intel_context.c | 6 --
src/mesa/drivers/dri/i965/brw_context.c | 6 --
src/mesa/main/context.c | 82 +++++++++++++++-----
src/mesa/main/mtypes.h | 6 ++
11 files changed, 213 insertions(+), 37 deletions(-)
create mode 100644 docs/specs/MESA_configless_context.spec
diff --git a/docs/specs/MESA_configless_context.spec b/docs/specs/MESA_configless_context.spec
new file mode 100644
index 0000000..8bed90d
--- /dev/null
+++ b/docs/specs/MESA_configless_context.spec
@@ -0,0 +1,120 @@
+Name
+
+ MESA_configless_context
+
+Name Strings
+
+ EGL_MESA_configless_context
+
+Contact
+
+ Neil Roberts <neil.s.roberts at intel.com>
+
+Status
+
+ Proposal
+
+Version
+
+ Version 1, February 28, 2014
+
+Number
+
+ EGL Extension #not assigned
+
+Dependencies
+
+ Requires EGL 1.4 or later. This extension is written against the
+ wording of the EGL 1.4 specification.
+
+Overview
+
+ This extension provides a means to use a single context to render to
+ multiple surfaces which have different EGLConfigs. Without this extension
+ the EGLConfig for every surface used by the context must be compatible
+ with the one used by the context. The only way to render to surfaces with
+ different formats would be to create multiple contexts but this is
+ inefficient with modern GPUs where this restriction is unnecessary.
+
+IP Status
+
+ Open-source; freely implementable.
+
+New Procedures and Functions
+
+ None.
+
+New Tokens
+
+ Accepted as <config> in eglCreateContext
+
+ EGL_NO_CONFIG_MESA ((EGLConfig)0)
+
+Additions to the EGL Specification section "2.2 Rendering Contexts and Drawing
+Surfaces"
+
+ Add the following to the 3rd paragraph:
+
+ "EGLContexts can also optionally be created with respect to an EGLConfig
+ depending on the parameters used at creation time. If a config is provided
+ then additional restrictions apply on what surfaces can be used with the
+ context."
+
+ Replace the last sentence of the 6th paragraph with:
+
+ "In order for a context to be compatible with a surface they both must have
+ been created with respect to the same EGLDisplay. If the context was
+ created without respect to an EGLConfig then there are no further
+ constraints. Otherwise they are only compatible if:"
+
+ Remove the last bullet point in the list of constraints.
+
+Additions to the EGL Specification section "3.7.1 Creating Rendering Contexts"
+
+ Replace the paragraph starting "If config is not a valid EGLConfig..."
+ with
+
+ "The config argument can either be a valid EGLConfig or EGL_NO_CONFIG_MESA.
+ If it is neither of these then an EGL_BAD_CONFIG error is generated. If a
+ valid config is passed then the error will also be generated if the config
+ does not support the requested client API (this includes requesting
+ creation of an OpenGL ES 1.x context when the EGL_RENDERABLE_TYPE
+ attribute of config does not contain EGL_OPENGL_ES_BIT, or creation of an
+ OpenGL ES 2.x context when the attribute does not contain
+ EGL_OPENGL_ES2_BIT).
+
+ Passing EGL_NO_CONFIG_MESA will create a configless context. When a
+ configless context is used with the OpenGL API it can be assumed that the
+ initial values of the context's state will be decided when the context is
+ first made current. In particular this means that the decision of whether
+ to use GL_BACK or GL_FRONT for the initial value of the first output in
+ glDrawBuffers will be decided based on the config of the draw surface when
+ it is first bound. If the context is later bound to another surface with a
+ different config it will not alter the context's state. This means that is
+ possible to have the draw buffer set to GL_BACK with a single-buffered
+ surface. The results of drawing in this case are undefined. The OpenGL ES
+ 3.0 API does not have this problem and instead the default is always
+ GL_BACK which has a special interpretation depending on how many buffers
+ the surface has."
+
+Additions to the EGL Specification section "3.7.3 Binding Contexts and
+Drawables"
+
+ Replace the first bullet point with the following:
+
+ "* If draw or read are not compatible with ctx as described in section 2.2,
+ then an EGL_BAD_MATCH error is generated."
+
+ Add a second bullet point after that:
+
+ "* If draw and read are not compatible with each other as described in
+ section 2.2, then an EGL_BAD_MATCH error is generated."
+
+Issues
+
+ None.
+
+Revision History
+
+ Version 1, February 28, 2014
+ Initial draft (Neil Roberts)
diff --git a/include/EGL/eglext.h b/include/EGL/eglext.h
index 1d68178..fc53914 100644
--- a/include/EGL/eglext.h
+++ b/include/EGL/eglext.h
@@ -571,6 +571,11 @@ EGLAPI EGLBoolean EGLAPIENTRY eglSwapBuffersWithDamageEXT( EGLDisplay dpy, EGLSu
typedef EGLBoolean (EGLAPIENTRYP PFNEGLSWAPBUFFERSWITHDAMAGEEXTPROC)(EGLDisplay dpy, EGLSurface surface, EGLint *rects, EGLint n_rects);
#endif
+#ifndef EGL_MESA_configless_context
+#define EGL_MESA_configless_context 1
+#define EGL_NO_CONFIG_MESA ((EGLConfig)0)
+#endif
+
#include <EGL/eglmesaext.h>
#ifdef __cplusplus
diff --git a/src/egl/drivers/dri2/egl_dri2.c b/src/egl/drivers/dri2/egl_dri2.c
index 892f1f4..f304075 100644
--- a/src/egl/drivers/dri2/egl_dri2.c
+++ b/src/egl/drivers/dri2/egl_dri2.c
@@ -508,6 +508,7 @@ dri2_setup_screen(_EGLDisplay *disp)
assert(dri2_dpy->dri2 || dri2_dpy->swrast);
disp->Extensions.KHR_surfaceless_context = EGL_TRUE;
+ disp->Extensions.MESA_configless_context = EGL_TRUE;
if (dri2_dpy->dri2 && dri2_dpy->dri2->base.version >= 3) {
disp->Extensions.KHR_create_context = EGL_TRUE;
diff --git a/src/egl/main/eglapi.c b/src/egl/main/eglapi.c
index 42bcb72..950c447 100644
--- a/src/egl/main/eglapi.c
+++ b/src/egl/main/eglapi.c
@@ -431,7 +431,7 @@ eglCreateContext(EGLDisplay dpy, EGLConfig config, EGLContext share_list,
_EGL_CHECK_DISPLAY(disp, EGL_NO_CONTEXT, drv);
- if (!config)
+ if (!config && !disp->Extensions.MESA_configless_context)
RETURN_EGL_ERROR(disp, EGL_BAD_CONFIG, EGL_NO_CONTEXT);
if (!share && share_list != EGL_NO_CONTEXT)
diff --git a/src/egl/main/eglcontext.c b/src/egl/main/eglcontext.c
index 79a92c7..70277ab 100644
--- a/src/egl/main/eglcontext.c
+++ b/src/egl/main/eglcontext.c
@@ -523,10 +523,22 @@ _eglCheckMakeCurrent(_EGLContext *ctx, _EGLSurface *draw, _EGLSurface *read)
return _eglError(EGL_BAD_ACCESS, "eglMakeCurrent");
}
- /* simply require the configs to be equal */
- if ((draw && draw->Config != ctx->Config) ||
- (read && read->Config != ctx->Config))
- return _eglError(EGL_BAD_MATCH, "eglMakeCurrent");
+ /* If the context has a config then it must match that of the two
+ * surfaces */
+ if (ctx->Config) {
+ if ((draw && draw->Config != ctx->Config) ||
+ (read && read->Config != ctx->Config))
+ return _eglError(EGL_BAD_MATCH, "eglMakeCurrent");
+ } else {
+ /* Otherwise we must be using the EGL_MESA_configless_context
+ * extension */
+ assert(dpy->Extensions.MESA_configless_context);
+
+ /* The extension doesn't permit binding draw and read buffers with
+ * differing contexts */
+ if (draw && read && draw->Config != read->Config)
+ return _eglError(EGL_BAD_MATCH, "eglMakeCurrent");
+ }
switch (ctx->ClientAPI) {
/* OpenGL and OpenGL ES are conflicting */
diff --git a/src/egl/main/egldisplay.h b/src/egl/main/egldisplay.h
index 66aaff5..0952bc9 100644
--- a/src/egl/main/egldisplay.h
+++ b/src/egl/main/egldisplay.h
@@ -89,6 +89,7 @@ struct _egl_extensions
EGLBoolean MESA_copy_context;
EGLBoolean MESA_drm_display;
EGLBoolean MESA_drm_image;
+ EGLBoolean MESA_configless_context;
EGLBoolean WL_bind_wayland_display;
EGLBoolean WL_create_wayland_buffer_from_image;
diff --git a/src/egl/main/eglmisc.c b/src/egl/main/eglmisc.c
index 341a723..65669d8 100644
--- a/src/egl/main/eglmisc.c
+++ b/src/egl/main/eglmisc.c
@@ -90,6 +90,7 @@ _eglUpdateExtensionsString(_EGLDisplay *dpy)
_EGL_CHECK_EXTENSION(MESA_copy_context);
_EGL_CHECK_EXTENSION(MESA_drm_display);
_EGL_CHECK_EXTENSION(MESA_drm_image);
+ _EGL_CHECK_EXTENSION(MESA_configless_context);
_EGL_CHECK_EXTENSION(WL_bind_wayland_display);
_EGL_CHECK_EXTENSION(WL_create_wayland_buffer_from_image);
diff --git a/src/mesa/drivers/dri/i915/intel_context.c b/src/mesa/drivers/dri/i915/intel_context.c
index 0cb1fea..a6057d3 100644
--- a/src/mesa/drivers/dri/i915/intel_context.c
+++ b/src/mesa/drivers/dri/i915/intel_context.c
@@ -410,7 +410,6 @@ intelInitContext(struct intel_context *intel,
__DRIscreen *sPriv = driContextPriv->driScreenPriv;
struct intel_screen *intelScreen = sPriv->driverPrivate;
int bo_reuse_mode;
- struct gl_config visual;
/* Can't rely on invalidate events, fall back to glViewport hack */
if (!driContextPriv->driScreenPriv->dri2.useInvalidate)
@@ -418,11 +417,6 @@ intelInitContext(struct intel_context *intel,
else
functions->Viewport = intel_viewport;
- if (mesaVis == NULL) {
- memset(&visual, 0, sizeof visual);
- mesaVis = &visual;
- }
-
intel->intelScreen = intelScreen;
if (!_mesa_initialize_context(&intel->ctx, api, mesaVis, shareCtx,
diff --git a/src/mesa/drivers/dri/i965/brw_context.c b/src/mesa/drivers/dri/i965/brw_context.c
index 1441b46..ad5e729 100644
--- a/src/mesa/drivers/dri/i965/brw_context.c
+++ b/src/mesa/drivers/dri/i965/brw_context.c
@@ -584,7 +584,6 @@ brwCreateContext(gl_api api,
struct intel_screen *screen = sPriv->driverPrivate;
const struct brw_device_info *devinfo = screen->devinfo;
struct dd_function_table functions;
- struct gl_config visual;
/* Only allow the __DRI_CTX_FLAG_ROBUST_BUFFER_ACCESS flag if the kernel
* provides us with context reset notifications.
@@ -651,11 +650,6 @@ brwCreateContext(gl_api api,
struct gl_context *ctx = &brw->ctx;
- if (mesaVis == NULL) {
- memset(&visual, 0, sizeof visual);
- mesaVis = &visual;
- }
-
if (!_mesa_initialize_context(ctx, api, mesaVis, shareCtx, &functions)) {
*dri_ctx_error = __DRI_CTX_ERROR_NO_MEMORY;
fprintf(stderr, "%s: failed to init mesa context\n", __FUNCTION__);
diff --git a/src/mesa/main/context.c b/src/mesa/main/context.c
index 5b77ce1..cd009c1 100644
--- a/src/mesa/main/context.c
+++ b/src/mesa/main/context.c
@@ -1013,7 +1013,8 @@ _mesa_initialize_dispatch_tables(struct gl_context *ctx)
*
* \param ctx the context to initialize
* \param api the GL API type to create the context for
- * \param visual describes the visual attributes for this context
+ * \param visual describes the visual attributes for this context or NULL to
+ * create a configless context
* \param share_list points to context to share textures, display lists,
* etc with, or NULL
* \param driverFunctions table of device driver functions for this context
@@ -1033,12 +1034,20 @@ _mesa_initialize_context(struct gl_context *ctx,
assert(driverFunctions->FreeTextureImageBuffer);
ctx->API = api;
- ctx->Visual = *visual;
ctx->DrawBuffer = NULL;
ctx->ReadBuffer = NULL;
ctx->WinSysDrawBuffer = NULL;
ctx->WinSysReadBuffer = NULL;
+ if (visual) {
+ ctx->Visual = *visual;
+ ctx->HasConfig = GL_TRUE;
+ }
+ else {
+ memset(&ctx->Visual, 0, sizeof ctx->Visual);
+ ctx->HasConfig = GL_FALSE;
+ }
+
if (_mesa_is_desktop_gl(ctx)) {
_mesa_override_gl_version(ctx);
}
@@ -1145,7 +1154,8 @@ fail:
* the rendering context.
*
* \param api the GL API type to create the context for
- * \param visual a struct gl_config pointer (we copy the struct contents)
+ * \param visual a struct gl_config pointer (we copy the struct contents) or
+ * NULL to create a configless context
* \param share_list another context to share display lists with or NULL
* \param driverFunctions points to the dd_function_table into which the
* driver has plugged in all its special functions.
@@ -1160,8 +1170,6 @@ _mesa_create_context(gl_api api,
{
struct gl_context *ctx;
- ASSERT(visual);
-
ctx = calloc(1, sizeof(struct gl_context));
if (!ctx)
return NULL;
@@ -1475,6 +1483,54 @@ _mesa_check_init_viewport(struct gl_context *ctx, GLuint width, GLuint height)
}
}
+static void
+handle_first_current(struct gl_context *ctx)
+{
+ GLenum buffer;
+ GLint bufferIndex;
+
+ assert(ctx->Version > 0);
+
+ ctx->Extensions.String = _mesa_make_extension_string(ctx);
+
+ check_context_limits(ctx);
+
+ /* According to GL_MESA_configless_context the default value of
+ * glDrawBuffers depends on the config of the first surface it is bound to.
+ * For GLES it is always GL_BACK which has a magic interpretation */
+ if (!ctx->HasConfig && _mesa_is_desktop_gl(ctx)) {
+ if (ctx->DrawBuffer != _mesa_get_incomplete_framebuffer()) {
+ if (ctx->DrawBuffer->Visual.doubleBufferMode)
+ buffer = GL_BACK;
+ else
+ buffer = GL_FRONT;
+
+ _mesa_drawbuffers(ctx, 1, &buffer, NULL /* destMask */);
+ }
+
+ if (ctx->ReadBuffer != _mesa_get_incomplete_framebuffer()) {
+ if (ctx->ReadBuffer->Visual.doubleBufferMode) {
+ buffer = GL_BACK;
+ bufferIndex = BUFFER_BACK_LEFT;
+ }
+ else {
+ buffer = GL_FRONT;
+ bufferIndex = BUFFER_FRONT_LEFT;
+ }
+
+ _mesa_readbuffer(ctx, buffer, bufferIndex);
+ }
+ }
+
+ /* We can use this to help debug user's problems. Tell them to set
+ * the MESA_INFO env variable before running their app. Then the
+ * first time each context is made current we'll print some useful
+ * information.
+ */
+ if (_mesa_getenv("MESA_INFO")) {
+ _mesa_print_info(ctx);
+ }
+}
/**
* Bind the given context to the given drawBuffer and readBuffer and
@@ -1567,21 +1623,7 @@ _mesa_make_current( struct gl_context *newCtx,
}
if (newCtx->FirstTimeCurrent) {
- assert(newCtx->Version > 0);
-
- newCtx->Extensions.String = _mesa_make_extension_string(newCtx);
-
- check_context_limits(newCtx);
-
- /* We can use this to help debug user's problems. Tell them to set
- * the MESA_INFO env variable before running their app. Then the
- * first time each context is made current we'll print some useful
- * information.
- */
- if (_mesa_getenv("MESA_INFO")) {
- _mesa_print_info(newCtx);
- }
-
+ handle_first_current(newCtx);
newCtx->FirstTimeCurrent = GL_FALSE;
}
}
diff --git a/src/mesa/main/mtypes.h b/src/mesa/main/mtypes.h
index d05649c..d18082f 100644
--- a/src/mesa/main/mtypes.h
+++ b/src/mesa/main/mtypes.h
@@ -4220,6 +4220,12 @@ struct gl_context
GLboolean FirstTimeCurrent;
/*@}*/
+ /**
+ * False if this context was created without a config. This is needed
+ * because the initial state of glDrawBuffers depends on this
+ */
+ GLboolean HasConfig;
+
/** software compression/decompression supported or not */
GLboolean Mesa_DXTn;
--
1.8.5.3
More information about the wayland-devel
mailing list