CODEWITHSUNDEEP
c++graphics3dsegmentation-faultvulkan
janekb04
janekb04

Reputation: 4915

Using Vulkan-hpp vk::enumerateInstanceVersion() causes segfault

I encountered a weird issue. I can use vkEnumerateInstanceVersion from vulkan.h, but using vk::enumerateInstanceVersion() from vulkan.hpp causes an memory access violation (segfault).

I use this function to create the vk::Instance:

static vk::Instance createInstance()
{
    loadVulkanGlobalFunctions();

    uint32_t version;
    vkEnumerateInstanceVersion(&version); // works fine, returns version 1.2.131
    version = vk::enumerateInstanceVersion(); // error 0xC0000005 memory access violation

    std::cout << "Supported Vulkan Version is "
              << VK_VERSION_MAJOR(version) << '.'
              << VK_VERSION_MINOR(version) << '.'
              << VK_VERSION_PATCH(version) << '\n';

    // instance creation ...
}

I load global Vulkan functions using the default dynamic loader:

static void loadVulkanGlobalFunctions()
{
    vk::DynamicLoader loader;
    auto vkGetInstanceProcAddr = loader.getProcAddress<PFN_vkGetInstanceProcAddr>("vkGetInstanceProcAddr");
    VULKAN_HPP_DEFAULT_DISPATCHER.init(vkGetInstanceProcAddr);
}

I #define VULKAN_HPP_DISPATCH_LOADER_DYNAMIC 1 before #include <vulkan/vulkan.hpp> and I have VULKAN_HPP_DEFAULT_DISPATCH_LOADER_DYNAMIC_STORAGE exactly once in my code.

Upvotes: 1

Views: 855

Answers (1)

janekb04
janekb04

Reputation: 4915

It turned out that the vk::DynamicLoader object created in loadVulkanGlobalFunctions must have its lifetime extended, as it unloads the dynamic library in its destructor. As it is a local variable that happens when loadVulkanGlobalFunctions exits and the stack unwinds. I simply changed it to this:

static vk::DynamicLoader createVulkanLoader()
{
    vk::DynamicLoader loader;
    auto vkGetInstanceProcAddr = loader.getProcAddress<PFN_vkGetInstanceProcAddr>("vkGetInstanceProcAddr");
    VULKAN_HPP_DEFAULT_DISPATCHER.init(vkGetInstanceProcAddr);
    return loader;
}

And assigned the result to a variable, whose lifetime is longer than of the vkInstance.

Upvotes: 1

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