> When you use user space drivers, you no longer have that protection. Since this is so off topic I'll just say, anyone interested about this topic, there is plenty of tutorials and articles about sane user space device drivers, along with production quality open source drivers. The acceptance of the concept is somewhat new, and there are many misconceptions.
On Fri, Mar 7, 2014 at 2:02 PM, John Syn <john3...@gmail.com> wrote: > > From: Brandon I <brandon.ir...@gmail.com> > Reply-To: <beagleboard@googlegroups.com> > Date: Friday, March 7, 2014 at 1:27 PM > To: <beagleboard@googlegroups.com> > Cc: <c...@isbd.net> > Subject: [beagleboard] Re: Writing 8-bit data to GPIO pins - does one > have to do it a bit at a time? > > user space should not know how you talk to it physically > > > I don't think this is generally accepted, otherwise user space device > drivers wouldn't exist: > http://www.embedded.com/design/operating-systems/4401769/Device-drivers-in-user-space > > With user space device drivers, you're free to push as little or as much > into the kernel as you like. > > The normal practice is that a badly behaving user space application should > not kill your complete system. Only the user space app should die. When you > use user space drivers, you no longer have that protection. User space > drivers are generally not a good idea unless you want to avoid the > user/kernel switching delays. > > Regards, > John > > > -Brandon > > On Thursday, March 6, 2014 12:06:43 PM UTC-8, robert.berger wrote: >> >> Hi, >> >> On Thursday, March 6, 2014 11:25:14 AM UTC+2, c...@isbd.net wrote: >>> >>> All the examples and libraries (Python mostly) that I can find for >>> doing IO to the GPIO pins seem to handle only a bit at a time. This >>> is fine for things like driving relays and LEDs but makes little sense >>> for 8-bit data. >>> >>> >> Taking your example. If we are talking about a device you want to connect >> to your beagle user space should not know how you talk to it physically and >> whether it's 8-bit data or i2c or something else underneath. Having said >> that there was/is some attempt to do what you want in kernel space [1] and >> it's called block GPIO [2] but I don't think it made it into mainline. >> >> Regards, >> >> Robert >> >> [1] http://lwn.net/Articles/533632/ >> [2] http://lwn.net/Articles/533557/ >> > -- > For more options, visit http://beagleboard.org/discuss > --- > You received this message because you are subscribed to the Google Groups > "BeagleBoard" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to beagleboard+unsubscr...@googlegroups.com. > > For more options, visit https://groups.google.com/d/optout. > > -- > For more options, visit http://beagleboard.org/discuss > --- > You received this message because you are subscribed to a topic in the > Google Groups "BeagleBoard" group. > To unsubscribe from this topic, visit > https://groups.google.com/d/topic/beagleboard/91ikp6Mxi0s/unsubscribe. > To unsubscribe from this group and all its topics, send an email to > beagleboard+unsubscr...@googlegroups.com. > For more options, visit https://groups.google.com/d/optout. > -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to beagleboard+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
