Mali and Vulkan on Linux fbdev

This is done through VK_KHR_display extension. Instead of creating a VkSurfaceKHR from X11/Wayland window handles, there is a special API to query display modes and you can create a VkSurfaceKHR directly from that API.

!! Thanks for the answer and these precious informations !

Will the code described in the aforementioned extension proposal text do the trick ?

The extension proposal text being :

http://vulkan-spec-chunked.ahcox.com/apes04.html

They seem to suggest using this code :

    extern VkBool32 ModeMatchesMyCriteria(const VkDisplayModePropertiesKHR *m);
    extern VkInstance instance;
    extern VkPhysicalDevice physDevice;
    extern VkSurfaceKHR surface;

    uint32_t displayCount, planeCount, i, j, k;
    VkDisplayPropertiesKHR* pDisplayProps;
    VkDisplayPlanePropertiesKHR* pPlaneProps;
    VkDisplayModeKHR myMode = VK_NULL_HANDLE;
    VkDisplayKHR myDisplay = VK_NULL_HANDLE;
    uint32_t bestPlane = UINT32_MAX;
    VkDisplayPlaneAlphaFlagBitsKHR alphaMode = 0;
    PFN_vkGetPhysicalDeviceDisplayPropertiesKHR pfnGetPhysicalDeviceDisplayPropertiesKHR;
    PFN_vkGetPhysicalDeviceDisplayPlanePropertiesKHR pfnGetPhysicalDeviceDisplayPlanePropertiesKHR;
    PFN_vkGetDisplayModePropertiesKHR pfnGetDisplayModePropertiesKHR;
    PFN_vkGetDisplayPlaneCapabilitiesKHR pfnGetDisplayPlaneCapabilitiesKHR;
    PFN_vkGetDisplayPlaneSupportedDisplaysKHR pfnGetDisplayPlaneSupportedDisplaysKHR;
    PFN_vkCreateDisplayPlaneSurfaceKHR pfnCreateDisplayPlaneSurfaceKHR;

    pfnGetPhysicalDeviceDisplayPropertiesKHR =
        (PFN_vkGetPhysicalDeviceDisplayPropertiesKHR)
        vkGetInstanceProcAddr(instance, "vkGetPhysicalDeviceDisplayPropertiesKHR");
    pfnGetPhysicalDeviceDisplayPlanePropertiesKHR =
        (PFN_vkGetPhysicalDeviceDisplayPlanePropertiesKHR)
        vkGetInstanceProcAddr(instance, "vkGetPhysicalDeviceDisplayPlanePropertiesKHR");
    pfnGetDisplayModePropertiesKHR =
        (PFN_vkGetDisplayModePropertiesKHR)
        vkGetInstanceProcAddr(instance, "vkGetDisplayModePropertiesKHR");
    pfnGetDisplayPlaneCapabilitiesKHR =
        (PFN_vkGetDisplayPlaneCapabilitiesKHR)
        vkGetInstanceProcAddr(instance, "vkGetDisplayPlaneCapabilitiesKHR");
    pfnGetDisplayPlaneSupportedDisplaysKHR =
        (PFN_vkGetDisplayPlaneSupportedDisplaysKHR)
        vkGetInstanceProcAddr(instance, "vkGetDisplayPlaneSupportedDisplaysKHR");
    pfnCreateDisplayPlaneSurfaceKHR =
        (PFN_vkCreateDisplayPlaneSurfaceKHR)
        vkGetInstanceProcAddr(instance, "vkCreateDisplayPlaneSurfaceKHR");

    // Get a list of displays on a physical device
    displayCount = 0;
    pfnGetPhysicalDeviceDisplayPropertiesKHR(physDevice, &displayCount, NULL);

    pDisplayProps = (VkDisplayPropertiesKHR*)malloc(sizeof(VkDisplayPropertiesKHR) * displayCount);
    pfnGetPhysicalDeviceDisplayPropertiesKHR(physDevice, &displayCount, pDisplayProps);

    // Get a list of display planes on a physical device
    planeCount = 0;
    pfnGetPhysicalDeviceDisplayPlanePropertiesKHR(physDevice, &planeCount, NULL);
    pPlaneProps = (VkDisplayPlanePropertiesKHR*)malloc(sizeof(VkDisplayPlanePropertiesKHR) * planeCount);
    pfnGetPhysicalDeviceDisplayPlanePropertiesKHR(physDevice, &planeCount, pPlaneProps);

    // Get the list of pModes each display supports
    for (i = 0; i < displayCount; ++i)
    {
        VkDisplayKHR display = pDisplayProps[i].display;
        VkDisplayModePropertiesKHR* pModes;
        uint32_t modeCount;

        vkGetDisplayModePropertiesKHR(physDevice, display, &modeCount, NULL);

        pModes = (VkDisplayModePropertiesKHR*)malloc(sizeof(VkDisplayModePropertiesKHR) * modeCount);
        vkGetDisplayModePropertiesKHR(physDevice, display, &modeCount, pModes);

        myMode = VK_NULL_HANDLE;
        for (j = 0; j < modeCount; ++j)
        {
            const VkDisplayModePropertiesKHR* mode = &pModes[i];

            if (ModeMatchesMyCriteria(mode))
            {
                myMode = mode->displayMode;
                break;
            }
        }

        free(pModes);

        // If there are no useable pModes found then check the next display.
        if (myMode == VK_NULL_HANDLE)
            continue;

        // Find a plane that matches these criteria, in order of preference:
        // -Is compatible with the chosen display + mode.
        // -Isn't currently bound to another display.
        // -Supports per-pixel alpha, if possible.
        for (j = 0; j < planeCount; ++j)
        {
            uint32_t supportedCount = 0;
            VkDisplayKHR* pSupportedDisplays;
            VkDisplayPlaneCapabilitiesKHR planeCaps;
            // See if the plane is compatible with the current display.
            pfnGetDisplayPlaneSupportedDisplaysKHR(physDevice, j, &supportedCount, NULL);

            // Plane doesn't support any displays.  This might happen on a card
            // that has a fixed mapping between planes and connectors when no
            // displays are currently attached to this plane's conector, for
            // example.
            if (supportedCount == 0)
                continue;

            pSupportedDisplays = (VkDisplayKHR*)malloc(sizeof(VkDisplayKHR) * supportedCount);
            pfnGetDisplayPlaneSupportedDisplaysKHR(physDevice, j, &supportedCount, pSupportedDisplays);

            for (k = 0; k < supportedCount; ++k)
                if (pSupportedDisplays[k] == display) {
                    // If no supported plane has yet been found, this is
                    // currently the best available plane.
                    if (bestPlane == UINT32_MAX)
                        bestPlane = j;
                    break;
                }

            // If the plane can't be used with the chosen display, keep looking.
            // Each display must have at least one compatible plane.
            if (k == supportedCount)
                continue;

            // If the plane passed the above test and is currently bound to the
            // desired display, or is not in use, it is the best plane found so
            // far.
            if ((pPlaneProps[j].currentDisplay == VK_NULL_HANDLE) &&
                (pPlaneProps[j].currentDisplay == display))
                bestPlane = j;
            else
                continue;

            pfnGetDisplayPlaneCapabilitiesKHR(physDevice, myMode, j, &planeCaps);

            // Prefer a plane that supports per-pixel alpha.
            if (planeCaps.supportedAlpha & VK_DISPLAY_PLANE_ALPHA_PER_PIXEL_BIT_KHR)
            {
                // This is the perfect plane for the given criteria.  Use it.
                bestPlane = j;
                alphaMode = VK_DISPLAY_PLANE_ALPHA_PER_PIXEL_BIT_KHR;
                break;
            }
        }
    }

    free(pDisplayProps);

    if (myDisplay == VK_NULL_HANDLE || myMode == VK_NULL_HANDLE) {
        // No suitable display + mode could be found.  Abort.
        abort();
    } else {
        // Success.  Create a VkSurfaceKHR object for this plane.
        const VkDisplaySurfaceCreateInfoKHR createInfo =
        {
            VK_STRUCTURE_TYPE_DISPLAY_SURFACE_CREATE_INFO_KHR,  // sType
            NULL,                                               // pNext
            0,                                                  // flags
            myMode,                                             // displayMode
            bestPlane,                                          // planeIndex
            pPlaneProps[bestPlane].currentStackIndex,           // planeStackIndex
            VK_SURFACE_TRANSFORM_IDENTITY_KHR,                  // transform
            1.0f,                                               // globalAlpha
            alphaMode,                                          // alphaMode
            ...
        }

        pfnCreateDisplayPlaneSurfaceKHR(instance, &createInfo, NULL, &surface);
    }

I guess that the key in creating the surface using this method is within vkCreateDisplayPlaneSurfaceKHR ?

Something like that, yes. We have a backend for it in our Vulkan SDK as well:

github.com/.../display.cpp

Alright, I'll take a look at that !

Thanks again for these informations. I might be able to get Vulkan working on Mali-T760 !