On Mon, Sep 13, 2010 at 11:42:57PM +0530, Gadiyar, Anand wrote: > On Mon, Sep 13, 2010 at 9:53 PM, Axel C. Voigt <avau@xxxxxx> wrote: > > Hello list, > > > > I am let alone with creating a linux process or kernel module that creates a > > virtual tty interface on one side and connects directly to the > > usbserial/ttyACM module (as if it were a usb serial device such as a modem) > > on the other end to be able to test the serial performance of a linux host. > > > > When achieved, I am planning to start a pppd on both sides to create a > > tcp-over-serial connection to transfer data such as an ftp up/download as if > > I were connected to the internet with a UMTS mobile phone or UMTS usb stick. > > This could then be evolved to have multiple "virtual" UMTS sticks connected > > to one linux host to generate load at the linux usb serial layer and is > > necessary since I want to be able to ensure that the new speed classes of > > serial devices such as HSDPA usb sticks (3.6 or 7.2MBit/s) or even DC-HSPA > > (> 50MBit/s) will work flawlessly even when you connect multiple sticks to > > one host. > > > > In the real world this setup will be difficult/impossible as one will rarely > > be able to find a mobile cell that supports >7,2MBit HSDPA (at least in my > > nearby area :-) as well as the data rate will significantly drop when you > > have more than one mobile in a mobile network cell! > > > > Could one give me a hint, how to create a test environment to artificially > > test such a scenario? Could one be of any help whether I can simulate a usb > > device in software? > > > > (Resending, as I accidentally knocked off the list last time around) > > How about using g_serial with dummy_hcd? Maybe you can use the n_ports > parameter to add more interfaces. > > (dummy_hcd gives you a virtual host and device controller pair, so you > can play with gadget drivers without needing actual gadget controller > hardware. g_serial can behave like a CDC ACM device). > > It won't be the same as having multiple different modems connected at > one time, but you will be able to have multiple serial port sessions > running. What about using a usb gadget device in a host machine at the same time? That way you can "loop back" the data through the same kernel at the same time, which should show up any bottlenecks pretty well. 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
