Hi Chia-I, Glad to see the fix goes so fast, thanks! I believe the direction is promising. And I am not familiar with the mapi module of mesa, so just one minor comment for the "glapi: Fix OpenGL and OpenGL ES interop" patch.
For changes in configure.ac, please use \" instead of \', i.e, GLAPI_OWNER='$(GL_LIB)' -> GLAPI_OWNER="$(GL_LIB)". Regards, Jammy On Mon, Dec 13, 2010 at 1:45 AM, Chia-I Wu <olva...@gmail.com> wrote: > On Fri, Dec 10, 2010 at 7:03 PM, Chia-I Wu <olva...@gmail.com> wrote: > > On Fri, Dec 10, 2010 at 4:01 PM, Jammy Zhou <jammy.z...@linaro.org> > wrote: > >> On Fri, Dec 10, 2010 at 3:13 PM, Chia-I Wu <olva...@gmail.com> wrote: > >>> With OpenGL ES coming to desktop, the way the current context/dispatch > >>> is stored, together with the way libGLES*.so is created, causes > >>> several issues[1]. The root of these issues is that the symbols > >>> defined in libGL.so and in libGLES*.so overlaps, and an application > >>> might link to both of them indirectly! > >>> > >>> In light of GLX_EXT_create_context_es2_profile, the simplest solution > >>> would be to stop distributing libGLES*.so. Applications will always > >>> link to libGL.so. Those that use GLX can then call glXGetProcAddress > >>> to get the addresses of OpenGL ES 2.0 functions. But those that use > >>> EGL will be in trouble. eglGetProcAddress is defined not to return > >>> the addresses of non-extension functions. > >> > >> I don't think it is a good solution to stop distributing libGLES*.so, > >> because in embeded/mobile world, a lot of applications have dependency > on > >> libGLES*.so instead of libGL.so. > > I am curious how other vendors solve this issue. Or more generally, > > how other toolkits solve providing mulitple shared libraries with > > overlapping symbols, and that are also supposed to be used altogether. > >>> > >>> If libGL.so and libGLES*.so both have to be distributed, then the > >>> question becomes how to handle symbols that overlaps gracefully. > >>> > >>> Accessing global variables such as _glapi_Context and _glapi_Dispatch > >>> will fail. Say libGL.so and libGLES*.so both has a copy of > >>> _glapi_Context. There is no guarantee that GET_CURRENT_CONTEXT will > >>> return the same context set by _glapi_set_context. > >>> > >>> Calling global functions will work as long as they are identical in > >>> both libGL.so and libGLES*.so. This means both libraries must agree > >>> on the order of slots in the dispatch table. And the problem with two > >>> copies of global _glapi_Dispatch also needs to be solved. > >>> > >>> One solution for these issues is to move _glapi_Context, > >>> _glapi_Dispatch, and _glapi_* functions to libglapi.so. libGL.so and > >>> libGLES*.so will both link to libglapi.so. All the libraries must be > >>> distributed together, as they must agree on the dispatch table used. > >>> This change should not break the ABI for existing DRI drivers. > > Or to pick one of the libraries to own libglapi, and have others link to > it. > I've been working toward this direction. libGL.so will provide > _glapi_* symbols as it is now. libGLES*.so will depend on libGL.so > instead of providing another copy of _glapi_*. On a x86 machine, > libGLESv1_CM.so and libGLESv2.so are down to 17K and 18K in size > respectively. The work can be found at > > > http://cgit.freedesktop.org/~olv/mesa/log/?h=esapi-rework<http://cgit.freedesktop.org/%7Eolv/mesa/log/?h=esapi-rework> > > Only the last commit is user-visible. It modifies configure.ac to > define GLAPI_OWNER, which is the library that owns _glapi_* symbols. > It is always $(GL_LIB) unless --disable-opengl is given. When > libGLES*.so is built, Makefile will check if libGLES*.so is > GLAPI_OWNER and decide whether libGLES*.so should define _glapi_* > symbols itself, or use those from GLAPI_OWNER. > > Internally, the branch modifies es1api and es2api to use mapi-based > glapi.h implementation. This switch is made because in the most > common case where libGL.so is GLAPI_OWNER, es1api and es2api is quite > different from glapi. It is not easy for them to share the same code > base. On the other hand, mapi is mroe flexible to fullfil both needs. > > The change to glapi is that 3 new extensions are added: > GL_ARB_ES2_compatibility, GL_OES_single_precision, and > GL_OES_fixed_point. There is no intention to support these > extensions. They are added so that dispatch table offsets are > assigned to OpenGL ES 1.1 and 2.0 functions. These offsets are then > shared with libGLES*.so. An implication of this is libGL.so and > libGLES*.so must be built from the same gl_API.xml as any change to > gl_API.xml may alter the offsets assigned. > > This limitation can actually be lifted by assigning fixed dispatch > offsets to OpenGL ES 1.1 and 2.0 functions, as is done for OpenGL 1.2 > and GL_ARB_multitexture functions. But I am not sure if it is a good > idea to assign fixed dispatch offsets to OpenGL ES 1.1 and 2.0 > functions. It is thus left out in this branch. > >>> Another option is make _glapi_Context and _glapi_Dispatch local. > >>> libGL.so, libGLES*.so, and every DRI driver will get a renamed local > >>> copy of _glapi_Context and _glapi_Dispatch. To not break the ABI for > >>> old DRI drivers, libGL.so and libGLES*.so will still export > >>> _glapi_Dispatch and _glapi_Context. But same as the first solution, > >>> there must be a big dispatch table that libGL.so and libGLES*.so can > >>> agree on. > > Sorry, this won't work. > >>> There should be other options, but these are all I have now. Any > >>> thought? > >>> > >>> [1] https://bugs.freedesktop.org/show_bug.cgi?id=32285 > >>> > >>> -- > >>> o...@lunarg.com > >>> _______________________________________________ > >>> mesa-dev mailing list > >>> mesa-dev@lists.freedesktop.org > >>> http://lists.freedesktop.org/mailman/listinfo/mesa-dev > >> > >> > > > > > > > > -- > > o...@lunarg.com > > > > > > -- > o...@lunarg.com >
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