Here are our requirements: Our custom Windows app must run on the host PC, but is not to be actually installed on the Windows host PC, so when our linux client device is plugged into the host, it must provide a filesystem from which the host will launch our custom Windows app. Once launched, our custom Windows app must capture the PC's display screen in real time and stream it over USB to the linux client device. From there, the linux client device will transfer the streaming data over Ethernet to another device. If you have a different data streaming solution that fits within the above requirements, then we'd certainly be interested in your guidance. Thanks again for all of your help. -----Original Message----- From: Greg KH [mailto:greg@xxxxxxxxx] Sent: Thursday, August 19, 2010 4:01 PM To: Murphy, Robert Cc: Alan Stern; Hardy, Ron; linux-usb@xxxxxxxxxxxxxxx Subject: Re: FW: Concerns regarding file backed storage gadget On Thu, Aug 19, 2010 at 01:47:48PM -0700, Murphy, Robert wrote: > > Why not just use a "streaming" client interface, like ACM or the serial > > driver instead of treating a filesystem not like a filesystem? > > One of requirements of the product I'm working on is that no Windows > driver installation be required. Windows supports these class interfaces just fine with no additional windows driver needed. And you are saying you have a custom Windows application, what makes that different from a windows driver? You could write a windows usb driver from userspace as well, no kernel driver needed. > > > You've got an unusual setup. Most people just stick a filesystem on > > > the gadget and use it that way. > > > Yes, but what's to prevent a host from treating this like a filesystem > > and use it that way? What happens if you plug this device into a > > windows machine without your special host software, or a OS-X or Linux > > machine? > > Actually, we need Windows to treat our Linux device to as a filesystem > so that the user can load and run the special Windows software that's > embedded in the backing file. Heh, that's a nice hack :) > The Windows software then reads/writes to what it sees as a 512kb > contiguous data file (literally called "data") in the exposed file > system. On the Linux device, our service does a look up of the offset > of the contiguous "data" file in the backing file and does it's reads > and writes from there. But as you are treating that "file" as a "stream", you might have some problems with it in the future as you are abusing the filesystem interface, right? Anyway, if you think this is the right thing for you to do, there's not much more we can do to change your mind, as long as you know the potential problems you might face with it. good luck, greg k-h -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
