From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vojtech Pavlik Date: Fri, 09 Feb 2001 18:53:25 +0000 Subject: Re: definition of terms (was: Re: Adding PCMCIA support to the kernel tree -- developers needed.) Message-Id: List-Id: References: In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-hotplug@vger.kernel.org On Fri, Feb 09, 2001 at 06:03:30PM +0100, Oliver Neukum wrote: > > > I fear we are being sucked down by semantics. > > > > You can't get away from that in design discussions. Gotta > > eliminate confusions up front. > > > > And this application structure is very important. You can't > > design a "system" without knowing the ways people interact > > with it ... /dev/NNN is no more than one part of a 1970s > > solution to a simpler system problem than we have today. > > We can still use it, but it's not a straightjacket to live in. > 'interface driver' - a kernel space driver that user space can use to talk to > a physical devices. There may be more than one interface driver per physical > device, or in rare cases, none. > > 'logical driver' - interface the user space agent may set up, which allows > the rest of user space to use the services a physical device offers, optional > logical driver: epson backend of SANE > interface driver: usbscanner.o > I introduced the term 'interface driver' because it is needed. But it's a very problematic one - there is nothing like a driver that connects directly hardware and userspace. There is always several drivers inbetween. In the case of USB scanner: [hw]--(pci)-->usb-ohci.c--(usb)-->scanner.c--(chardevice)-->[userland] In many cases there is much more. If there were only direct [hw]-->xxx.c-->[userland] drivers, we wouldn't need any hotplug support - kmod and friends would be enough, because we would then be able to load the modules based on userland requests. And that is not the case. For USB scanner working, we need both usb-ohci.c and scanner.c loaded. So, if you define 'interface driver' as the last driver instance before a layer (chardevice, netdevice, blockdevice) that interfaces to userland, then OK. But we need to take the other drivers into our view as well. -- Vojtech Pavlik SuSE Labs _______________________________________________ Linux-hotplug-devel mailing list http://linux-hotplug.sourceforge.net Linux-hotplug-devel@lists.sourceforge.net http://lists.sourceforge.net/lists/listinfo/linux-hotplug-devel