The following Vulkan related problems were found on emulator 35.1.18 and emu-master-dev.

While running android emulators with big parallelism (10+ instances in parallel) i've noticed that occasionally there are errors like:

ERROR   | emuglConfig_get_vulkan_hardware_gpu: Failed to create vulkan instance error code: -9

which do seem to affect the succeeding sessions. Most likely it could be a problem in the gpu vulkan library or smth else, but the issue is that I'm running the emulators with -feature -Vulkan to turn of Vulkan in order to be able to use snapshots, but nevertheless some Vulkan APIs are called (as seen from the error) which seems to cause issues at my scale. The problematic place seems to be emuglConfig_get_vulkan_hardware_gpu in external/qemu/android/android-ui/modules/aemu-gl-init/src/android/opengl/emugl_config.cpp (https://android.googlesource.com/platform/external/qemu/+/refs/heads/emu-master-dev/android/android-ui/modules/aemu-gl-init/src/android/opengl/emugl_config.cpp#246)

stack:

#0  emuglConfig_get_vulkan_hardware_gpu (vendor=0x7fffffffaca0, major=0x7fffffffac9c, minor=0x7fffffffac98, patch=0x7fffffffac94) at /home/rudolfs/Development/Google/aosp/external/qemu/android/android-ui/modules/aemu-gl-init/src/android/opengl/emugl_config.cpp:263
#1  0x00007ffff50936b0 in emuglConfig_init (config=0x7fffffffaf50, gpu_enabled=true, gpu_mode=0x7ffff3ff9856 "host", gpu_option=0x0, bitness=64, no_window=false, blacklisted=false, has_guest_renderer=true, uiPreferredBackend=0, use_host_vulkan=false) at /home/rudolfs/Development/Google/aosp/external/qemu/android/android-ui/modules/aemu-gl-init/src/android/opengl/emugl_config.cpp:687
#2  0x0000555558301de9 in androidEmuglConfigInit (config=0x7fffffffaf50, avdName=0x5555594724b0 "pixel6_13.0_1", avdArch=0x5555596c43a0 "x86_64", apiLevel=33, hasGoogleApis=true, gpuOption=0x0, hwGpuModePtr=0x555558c243f8 <s_hwConfig+312>, wantedBitness=0, noWindow=false, uiPreferredBackend=WINSYS_GLESBACKEND_PREFERENCE_AUTO, hostGpuVulkanBlacklisted=0x7fffffffaf0e, forceUseHostGpuVulkan=false) at /home/rudolfs/Development/Google/aosp/external/qemu/android/android-ui/modules/aemu-gl-init/src/android/main-emugl.cpp:103
#3  0x0000555557ff315d in configAndStartRenderer (uiPreferredBackend=WINSYS_GLESBACKEND_PREFERENCE_AUTO, config_out=0x7fffffffb808) at /home/rudolfs/Development/Google/aosp/external/qemu/android/android-ui/modules/aemu-ui-window/src/android/main-common-ui.c:286
#4  0x0000555556ee6743 in main (argc=0, argv=0x7fffffffd5f8) at /home/rudolfs/Development/Google/aosp/external/qemu/android-qemu2-glue/main.cpp:3258

For now I've been able to get around this by renaming the vulkan folder under lib64 so that no Vulkan API calls are ever made (the flow just stops since it cannot load the library), but could it be possible to adjust this so that -feature -Vulkan really disabled Vulkan.

Another much smaller related issues is that even with -feature -Vulkan, the following lines are logged:

Deciding if GLDirectMem/Vulkan should be enabled. Selected renderer: 1 API level: 34 host GPU on the denylist? 0
Host GPU selected, enabling Vulkan.

This seems to come from main-common-ui.c (https://android.googlesource.com/platform/external/qemu/+/refs/heads/emu-master-dev/android/android-ui/modules/aemu-ui-window/src/android/main-common-ui.c#315) which does not seem to honour the feature flag (eventually Vulkan is not used since lower in the logic it does check the override state, but that could have been done at the very start to avoid the confusing log messages).

Issue 356896486

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