On Thu, 2013-10-31 at 12:50 -0400, Przemek Klosowski wrote: > On 10/31/2013 02:03 AM, rran...@ihug.com.au wrote: > > I have run into an issue which seems to call into question the udev > > paradigm for USB devices. In my case it has ramifications in > > ModemManager and gpsd packages, but I see it as a fundamental problem > > with udev which is in all current versions of Fedora. > > > > My USB GPS is a BU-353 which uses a pl2303 USB-Serial Controller > > (idVendor=067b, idProduct=2303). However, bugzilla report 878737 > > indicates this same interface chip is used on other devices such as > > RS232-USB adapters. > > > > If the device is a GPS you do not want ModemManager run on it > > (bugzilla 1023234) but you do want gpsctl to tell gpsd about it when > > it is plugged in. If it is a RS232 adapter the opposite is true > > (bugzilla 878737). Note that it is reported that the DU-353 can be > > bricked if the wrong thing is written to it. > > > > After looking at the lsusb -v output for my BU-353 and the output for > > RS232 devices reported on the net, I do not see any way to distinguish > > between the two different types of devices that udev could use to tell > > them apart. > > > > Unless I am missing something this seems like a fatal flaw in the udev > > paradigm. > > > > As the others have said, there's no way to determine what's sitting > behind those serial controllers so it's not a problem with udev but with > the hardware it has to handle. The default udev setting is, or at least > used to be, designed for the most common case, which turns out wrong for > you. No matter what udev does, someone is not going to get their device > auto-configured, so the right choice is to handle the most common case. > > Now, it's possible that modems aren't just used much any more, so that > requiring manual scan would make sense, and udev makes it possible. > > By the way, it seems to me that on a computer with no modems, one should > simply uninistal ModemManager:
Not just a computer with no modems, but a computer into which you would never plug a modem and use it. These days, there aren't many 56k/POTS devices, but the vast vast majority are WWAN modems. And these are sometimes, especially in embedded cases, driven by generic serial converters like pl2xxx. If you're on a server, and that server does not have any "SMS me when you're down" functionality, then you may not want ModemManager installed there. But we'd also like to hear about devices that MM probes-but-shouldn't-probe so we can black/greylist them as appropriate. Dan -- devel mailing list devel@lists.fedoraproject.org https://admin.fedoraproject.org/mailman/listinfo/devel Fedora Code of Conduct: http://fedoraproject.org/code-of-conduct
