Chad Versace <chad.vers...@linux.intel.com> writes: > On 02/20/2013 05:44 PM, Eric Anholt wrote: >> Chad Versace <chad.vers...@linux.intel.com> writes: >> >>> -----BEGIN PGP SIGNED MESSAGE----- >>> Hash: SHA1 >>> >>> I'm seeking feedback on an EGL extension that I'm drafting. The ideas have >>> already been discussed at Khronos meetings to a good reception, but I want >>> feedback from Mesa developers too. >>> >>> Summary >>> - ------- >>> The extension, tentatively named EGL_EXT_platform_display, enables EGL >>> clients >>> to specify to which platform (X11, Wayland, gbm, etc) an EGL resource >>> (EGLDisplay, EGLSurface, etc) belongs when the resource is derived from >>> a platform-native type. As a corollary, the extension enables the creation >>> of >>> EGL resources from different platforms within a single process. >>> >>> >>> Feedback >>> - -------- >>> I'd like to hear feeback about the details below. Do you see any potential >>> problems? Is it lacking a feature that you believe should be present? >> >> Seems pretty reasonable as an outline. I'm not clear, though, what are >> the rules on sharing EGL resources like EGLImages between EGLDisplays? > > If I interpreted correctly all the pertinent EGL specs, currently no resource > sharing is allowed between EGLDisplays. So, the EGL_EXT_display_platform > doesn't need to define additional restrictions here. > > Here's my reasoning based on my interpretation of the specs. I can think of > four resources that can potentially be shared: > > - EGLContext > > The EGL 1.4 spec states that all contexts in a share group must belong to > the same display. This restriction should not be lifted by > EGL_EXT_platform_display. > > - EGLSurface > > I could find no text in the EGL 1.4 discussing sharing of EGLSurfaces, so > the > EGL_EXT_platform_display spec should explicitly ban sharing them between > displays from different platforms. If necessary, a layered extension can > add > sharing for special cases. > > - EGLImage > > EGLImages are created with respect to an EGLDisplay and EGLContext, so I > assume that they can be shared only among contexts within same share > group. > The EGL_KHR_image_base specs give any useful details about sharing. > > - EGLStream > > An EGLStream is created with respect to an EGLDisplay, but not a context. > Because the spec does not say otherwise, I assume EGLStreams also cannot > be shared across displays.
Good to hear.
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