3 MESA_image_dma_buf_export
7 EGL_MESA_image_dma_buf_export
15 Dave Airlie (airlied 'at' redhat 'dot' com)
23 Version 3, May 5, 2015
31 Requires EGL 1.4 or later. This extension is written against the
32 wording of the EGL 1.4 specification.
34 EGL_KHR_base_image is required.
36 The EGL implementation must be running on a Linux kernel supporting the
37 dma_buf buffer sharing mechanism.
41 This extension provides entry points for integrating EGLImage with the
42 dma-buf infrastructure. The extension allows creating a Linux dma_buf
43 file descriptor or multiple file descriptors, in the case of multi-plane
44 YUV image, from an EGLImage.
46 It is designed to provide the complementary functionality to
47 EGL_EXT_image_dma_buf_import.
51 Open-source; freely implementable.
55 This extension uses the 64-bit unsigned integer type EGLuint64KHR
56 first introduced by the EGL_KHR_stream extension, but does not
57 depend on that extension. The typedef may be reproduced separately
58 for this extension, if not already present in eglext.h.
60 typedef khronos_uint64_t EGLuint64KHR;
62 New Procedures and Functions
64 EGLBoolean eglExportDMABUFImageQueryMESA(EGLDisplay dpy,
68 EGLuint64KHR *modifiers);
70 EGLBoolean eglExportDMABUFImageMESA(EGLDisplay dpy,
81 Additions to the EGL 1.4 Specification:
83 To mirror the import extension, this extension attempts to return
84 enough information to enable an exported dma-buf to be imported
85 via eglCreateImageKHR and EGL_LINUX_DMA_BUF_EXT token.
87 Retrieving the information is a two step process, so two APIs
91 EGLBoolean eglExportDMABUFImageQueryMESA(EGLDisplay dpy,
95 EGLuint64KHR *modifiers);
97 is used to retrieve the pixel format of the buffer, as specified by
98 drm_fourcc.h, the number of planes in the image and the Linux
99 drm modifiers. <fourcc>, <num_planes> and <modifiers> may be NULL,
100 in which case no value is retrieved.
102 The second entrypoint retrieves the dma_buf file descriptors,
103 strides and offsets for the image. The caller should pass
104 arrays sized according to the num_planes values retrieved previously.
105 Passing arrays of the wrong size will have undefined results.
106 If the number of fds is less than the number of planes, then
107 subsequent fd slots should contain -1.
109 EGLBoolean eglExportDMABUFImageMESA(EGLDisplay dpy,
115 <fds>, <strides>, <offsets> can be NULL if the infomatation isn't
116 required by the caller.
120 1. Should the API look more like an attribute getting API?
122 ANSWER: No, from a user interface pov, having to iterate across calling
123 the API up to 12 times using attribs seems like the wrong solution.
125 2. Should the API take a plane and just get the fd/stride/offset for that
128 ANSWER: UNKNOWN,this might be just as valid an API.
130 3. Does ownership of the file descriptor remain with the app?
132 ANSWER: Yes, the app is responsible for closing any fds retrieved.
134 4. If number of planes and number of fds differ what should we do?
136 ANSWER: Return -1 for the secondary slots, as this avoids having
137 to dup the fd extra times to make the interface sane.
142 Just use the KHR 64-bit type.
143 Version 2, March, 2015
144 Add a query interface (Dave Airlie)
145 Version 1, June 3, 2014
146 Initial draft (Dave Airlie)