[linux] Added EGL headless backend support #7007

brunoabinader · 2016-11-10T18:00:05Z

Follow-up to the work started by @tiagovignatti in #5843 - thanks Tiago!

This PR implements EGL headless backend, using EGL_DEFAULT_DISPLAY as primary display - thus no need for handling render nodes directly via gbm.

Though we use software rendering via LLVMpipe, we still need a valid display for EGL to be properly initialized. On Travis CI, like the Qt builds, we still need to start Xvfb to obtain a valid display.

I've put some effort attempting to find a working setup for Mesa to have its EGL platform working with a native display that doesn't require a window system, but so far no success. The most promising option, though, comes from this recent Mesa extension - MESA_platform_surfaceless - that promises to provide a native display independent of any native window system. Given this solution already works and is testable via CI, we can pursuit this as a follow-up work.

mention-bot · 2016-11-10T18:00:12Z

@brunoabinader, thanks for your PR! By analyzing the history of the files in this pull request, we identified @kkaefer, @tmpsantos and @jfirebaugh to be potential reviewers.

kkaefer · 2016-11-11T11:15:50Z

.travis.yml

+      - &clang35_packages [ 'clang-3.5', 'libstdc++-4.9-dev', 'libstdc++6' ]
+      - &gcc5_packages [ 'gcc-5', 'g++-5' ]
+      - &egl_packages [ 'libgles2-mesa-dev', 'libgbm-dev' ]
+      - &glfw_packages [ 'libxrandr-dev', 'libxcursor-dev', 'libxinerama-dev' ]


kkaefer · 2016-11-11T11:17:11Z

platform/linux/config.cmake

+            PRIVATE platform/linux/src/headless_backend_egl.cpp
+            PRIVATE platform/linux/src/headless_display_egl.cpp
+        )
+        # XXX: Provide surface-less EGL mesa for CI builds.


remaining todo?

Yeah - #7020
I'll add that link to the comment 👍

kkaefer · 2016-11-11T11:27:34Z

platform/linux/src/headless_backend_egl.cpp

+    EGLDisplay display_ = display->attribute<EGLDisplay>();
+    EGLConfig& config = display->attribute<EGLConfig&>();
+
+    eglBindAPI(EGL_OPENGL_API);


missing error handling

kkaefer · 2016-11-11T11:29:08Z

platform/linux/src/headless_display_egl.cpp

+        EGL_ALPHA_SIZE, 0,
+        EGL_DEPTH_SIZE, 1,
+        EGL_RENDERABLE_TYPE, EGL_OPENGL_BIT,
+        EGL_NONE


Maybe add a note that the configuration here doesn't matter since we're rendering to a framebuffer anyway.

Good idea 👍

kkaefer · 2016-11-11T13:36:34Z

platform/linux/src/headless_backend_egl.cpp

+    EGLDisplay display_ = display->attribute<EGLDisplay>();
+    EGLConfig& config = display->attribute<EGLConfig&>();
+
+    if (!eglBindAPI(EGL_OPENGL_API)) {


You are setting MBGL_USE_GLES2 above, but requesting a desktop OpenGL API here. Did you try requesting EGL_OPENGL_ES_API?

Yes - I initially used EGL_OPENGL_ES_API, but then I obtained a crash right after when querying for the shading version string.

I believe this happens because when I attempt to use that enum, querying for the version string of my local EGL implementation returns Version: OpenGL ES-CM 1.1 Mesa 10.1.3. From the eglBindAPI documentation, it says eglBindAPI and the corresponding EGL_OPENGL_ES_API and EGL_OPENVG_API api parameters are supported only if the EGL version is 1.2 or greater.

kkaefer · 2016-11-11T15:59:31Z

platform/linux/src/headless_display_egl.cpp

@@ -25,6 +26,15 @@ HeadlessDisplay::Impl::Impl() {
        throw std::runtime_error("eglInitialize() failed.\n");
    }

+    if (major >= 1 && minor >= 2) {


that fails for EGL 2.0

kkaefer · 2016-11-11T16:00:52Z

platform/linux/src/headless_display_egl.cpp

@@ -25,6 +26,15 @@ HeadlessDisplay::Impl::Impl() {
        throw std::runtime_error("eglInitialize() failed.\n");
    }

+    if (major >= 1 && minor >= 2) {
+        EGLenum api = minor >= 4 ? EGL_OPENGL_API : EGL_OPENGL_ES_API;


also problematic works for 1.4, but not for 2.0? If it works, we /always/ want the OpenGL ES API, since that's what we're mainly targeting. We just happen to be largely compatible with Desktop OpenGL due to the limited featureset we're using.

brunoabinader · 2016-11-11T21:34:23Z

@kkaefer I found the reason why we were unable to compile the shader.

Even though we bind to EGL_OPENGL_ES_API by default, the client version is set to 1 by default when creating the context - which doesn't have support for OpenGL ES Shading Language. Support for shaders only comes with OpenGL ES 2.0.

To fix that, we need to pass EGL_CONTEXT_CLIENT_VERSION, 2 as an attribute inside attrib_list in which we pass to eglCreateContext.

brunoabinader · 2016-11-11T22:25:44Z

Heh, this worked better than I've expected: Because we really use OpenGL ES 2.0 client API, I had to append the code snippet below to each of the test shaders from OffscreenTexture.RenderToTexture to account for it:

#ifdef GL_ES
precision mediump float;
#endif

If my assumptions about Android using EGL as backend are correct, then this is probably one step further running core tests on Android.

brunoabinader · 2016-11-15T13:41:39Z

@kkaefer 🚢 ?

kkaefer

It looks like the only test that runs the render test-suite are the node-bindings, so it seems that we're only testing rendering with OSMesa, but not with EGL or GLX. Can we add on a render test to those as well?

brunoabinader · 2016-11-15T16:28:53Z

Can we add on a render test to those as well?

This is going to be provided in #7053 👍

Prevents some OpenGL implementations from bailing out.

brunoabinader · 2016-11-16T11:33:16Z

@kkaefer I've rebased this after #7053 got merged. There are now 4 new Travis CI builds added:

EGL:
- EGL/Node/Clang38/Debug: runs Node render/query tests
- EGL/GCC5/Release: runs core unit tests
GLX:
- GLX/Node/Clang38/Debug: runs Node render/query tests
- GLX/GCC5/Release: runs core unit tests

@mikemorris the added Node builds won't affect the release node build. These are just for ensuring our Node render/query test passes using these OpenGL APIs.

mikemorris · 2016-11-16T15:47:57Z

.travis.yml

      addons: *qt4
+      before_script:


Should the GLX - Node - Clang 3.8 - Release build currently using RUN_XVFB be switched to these setup scripts instead?

Yes, forgot about that :)

mikemorris · 2016-11-16T15:54:45Z

scripts/travis_setup.sh


+export -f mapbox_start_xvfb
+
+function mapbox_install_mesa_glx {


This is needed as a separate script for only the QT builds because Mesa is installed in platform/linux/config.cmake for Linux builds, right? Is there any way we could consolidate these into a single script that accepts args to install the necessary version of Mesa?

The instructions we set in platform/linux/config.cmake should be sufficient for all things Mapbox GL-wise. However, Qt libraries don't know about our custom libGL.so, so we must tell 'em to use it via LD_LIBRARY_PATH.

Because that's the only reason for having this function, I'm not sure if we should add extra functionality in this. Do we have a need for this elsewhere?

mikemorris · 2016-11-16T15:58:52Z

platform/linux/config.cmake

@@ -1,5 +1,5 @@
 mason_use(glfw VERSION 3.2.1)
-if (WITH_OSMESA OR IS_CI_BUILD)
+if(IS_CI_BUILD AND NOT WITH_EGL)


I'm a little confused by this - are we installing Mesa somewhere else for EGL CI builds? It appears that we're still setting MASON_MESA_SUFFIX for WITH_EGL builds in CMakeLists.txt.

I'm a little confused by this - are we installing Mesa somewhere else for EGL CI builds?

Yes - we are using the system's mesa install via libgles2-mesa-dev.

It appears that we're still setting MASON_MESA_SUFFIX for WITH_EGL builds in CMakeLists.txt.

That should cause no harm - it's going to be used when we get the EGL surface-less mesa build :)

Original author: Tiago Vignatti <tvignatti@gmail.com> Calling X11 window system is superfluous for headless rendering. This patch implements EGL platform using GBM, which is slightly more simple than the GLX path when using X11. In principle there are no big advantages in terms of performance etc. My motivation behind this was to get in touch with the code and the project. For testing I'm using: $ unset DISPLAY && ./build/linux-x86_64/Debug/mbgl-test v2: rebased patch against the new cmake changes; walk through render node to find a valid one; remove EGLSurface completely cause windows are not needed here.

jfirebaugh

I'm going to put the breaks on here for a sec. We already have quite a few rows in the Travis matrix, and frequently bump up against our built limits, leading to time waiting for the queue to clear.

Can we think about ways to make the matrix smaller?

brunoabinader · 2016-11-16T23:51:58Z

Can we think about ways to make the matrix smaller?

@jfirebaugh we've reduced the build matrix to 10 items.

👍

brunoabinader added Linux tests labels Nov 10, 2016

brunoabinader force-pushed the headless-egl branch 2 times, most recently from 6a1847e to 54997f1 Compare November 10, 2016 18:13

brunoabinader mentioned this pull request Nov 10, 2016

Replace GLX by EGL platform for headless view #5843

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Provide a surfaceless EGL headless backend #7020

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brunoabinader force-pushed the headless-egl branch 2 times, most recently from b9de0b3 to e9f3dce Compare November 11, 2016 12:55

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brunoabinader force-pushed the headless-egl branch from 5f46eb5 to 38d8fd6 Compare November 11, 2016 20:19

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brunoabinader force-pushed the headless-egl branch from 9a4f6cf to 882baa4 Compare November 14, 2016 14:23

mikemorris mentioned this pull request Nov 14, 2016

Switch Node Linux binary builds back to GLX/xvfb #7053

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kkaefer suggested changes Nov 15, 2016

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[test] Use shared headless display

fb04486

Prevents some OpenGL implementations from bailing out.

brunoabinader force-pushed the headless-egl branch 4 times, most recently from a06ae5a to 2247a0e Compare November 16, 2016 11:17

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brunoabinader force-pushed the headless-egl branch 2 times, most recently from e90a379 to 65d541c Compare November 16, 2016 18:11

brunoabinader added 2 commits November 16, 2016 19:17

[build] Added EGL & GLX CI builds

9a98d5f

[linux] Ensure EGL uses OpenGL ES 2.0 client API

23de317

brunoabinader force-pushed the headless-egl branch from 65d541c to 23de317 Compare November 16, 2016 18:17

brunoabinader mentioned this pull request Nov 16, 2016

[native] Skip debug/* render tests in Release mode mapbox/mapbox-gl-test-suite#175

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[build] Updated test-suite

bef0f95

brunoabinader force-pushed the headless-egl branch from ab4ad53 to bef0f95 Compare November 16, 2016 23:09

brunoabinader mentioned this pull request Nov 16, 2016

Update test-suite mapbox/mapbox-gl-js#3640

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brunoabinader merged commit a5ac643 into master Nov 17, 2016

brunoabinader deleted the headless-egl branch November 17, 2016 00:01

petrsloup mentioned this pull request Jan 18, 2017

EGL headless mode maptiler/tileserver-gl#71

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[linux] Added EGL headless backend support #7007

[linux] Added EGL headless backend support #7007

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		export -f mapbox_start_xvfb

		function mapbox_install_mesa_glx {

[linux] Added EGL headless backend support #7007

[linux] Added EGL headless backend support #7007

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