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qemu-xhci device should detect if libusb host supports streams
When using USB passthrough with the qemu-xhci (and nec-usb-xhci), streams are enabled by default, but if the host xHCI controller doesn't support them, it will trigger hard-to-debug UAS guest errors.
This should be possible to detect since the kernel returns ENOSYS (errno 38) when xhci host controller does not support streams:
libusb: error [do_streams_ioctl] streams-ioctl failed error -1 errno 38
qemu: libusb_alloc_streams: -99 [OTHER]
Maybe libusb should return a dedicated error instead of LIBUSB_ERROR_OTHER in this case, but qemu does not handle any other error code anyway.
Just trying to enable streams before enabling them in qemu should do it. I don't know if it should be done in hcd-xhci.c, host-libusb.c or elsewhere, but this would be detectable at launch instead of a static option true/false, maybe a ternary with auto would be better.
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