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Re: USB pass through into Mac OS 9.x with qemu-system-ppc

From: Howard Spoelstra
Subject: Re: USB pass through into Mac OS 9.x with qemu-system-ppc
Date: Tue, 16 Feb 2021 16:42:24 +0100

On Tue, Feb 16, 2021 at 3:48 PM Gerd Hoffmann <kraxel@redhat.com> wrote:
>   Hi,
> > Please find another pcap file attached. This one stems from an attempt
> > to pass through a midi device when running qemu-system-ppc with Mac OS
> > 9.2 in macOS host.
> Ah, yes, I remember now.  Problem is that the usb stick is plugged into
> a high-speed port (usb2) on the host but passed as full-speed device
> (usb1) to the guest.  That works in some cases, but is not guaranteed
> to work.  usb_host_speed_compat() tries to catch some of the
> incompatible cases.  The usb-storage incompatibility slips through
> because the incompatibility is specific to the mass storage protocol.
> Specifically the wMaxPacketSize is 64 for usb1 and 512 for usb2.
> Seems fedora deals better with the situation ...
> take care,
>   Gerd

Hi Gerd,

Thanks for looking into this. It looks to me that the usb storage
device nicely reports endpoints 1 and 2 when asked, but that the host
only ever communicates with endpoint 1.
Is that the issue you refer to, or might that be libusb related?

Can this also explain that other (non-mass-storage) devices cannot be
passed through successfully ?


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