| <!-- |
| Copyright 2018-2021 The Khronos Group Inc. |
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| SPDX-License-Identifier: CC-BY-4.0 |
| --> |
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| # What Happened To The Vulkan Extension Loader? |
| |
| If you're looking for the files vulkan_ext.[ch] in this directory, they have |
| been removed. There were two significant problems with these simple |
| wrappers. |
| |
| First, vulkan_ext exported all extension entrypoints. However, the Vulkan |
| loader also exports entrypoints for the window system integration |
| extensions. If someone tried to compile a project and link it to both the |
| loader and vulkan_ext, they would get a bunch of redefined symbols. This |
| linking error is difficult to work around, because vulkan_ext does not have |
| an easy method of disabling the entrypoints at compile time. It is possible |
| to remove these entrypoints when generating vulkan_ext, but even then you |
| have to manually compile a list of every single extension to be disabled. |
| |
| Second, each entrypoint is only stored once, regardless of how many |
| instances or devices are created. This means that attempting to use multiple |
| instances or devices in parallel can result in one device calling function |
| pointers that are only valid on the other device, which will crash. You may |
| be able to work around this by never initializing the device dispatch |
| (vkExtInitDevice), but we haven't tried this. |
| |
| It is still possible to retrieve the last versions of these files in the |
| Github KhronosGroup/Vulkan-Docs repository from the 'v1.1.75' release tag. |
| It is also possible to regenerate them from ../../xml/vk.xml, although we |
| are no longer maintaining the generator code and it may eventually stop |
| working correctly. See README.adoc and the `extloader` Makefile target in |
| that directory. |
