From mboxrd@z Thu Jan 1 00:00:00 1970 From: Oliver Neukum Date: Wed, 07 Feb 2001 22:43:24 +0000 Subject: 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 Mittwoch, 7. Februar 2001 22:14, David Brownell wrote: > > But stable names don't save you from a need to serialise due to reuse. > > In fact a stable name implies reuse, as it depends on bus location. > > Either you get unique or you get stable names. > > I also said (different word, true) that the names don't invalidate > (hence don't get reused!) while the agents operate. There were > two constraints I put in that "minimal" set; you' ve focussed on > the first one! OK. I had overlooked that. > > > USB device "/proc/bus/usb/002/031" may be network interface "usb0". > > > The lower level name (USB) is known before "usbnet" is loaded, > > > but "usb0" isn't known till afterwards ... but then, USB hotplugging > > > sees the USB name, and network hotplugging is what sees "usb0". > > > > True, but there's no equivalent for network hotplugging for other > > subsystems. > > Yet. The stack we're looking at today has two layers: bus (USB, PCI), > and "next" (network). Printers and disks will be layered above busses; > PCMCIA is another bus. I see. However as soon as you take PCI into the picture, that's all devices. It begins to look like recreating devfs. > > > > c) You'd need to call after drivers have bound to interfaces. > > > > > > USB hotplug is called after the kernel gives drivers a chance to > > > bind to interfaces. > > > > That's not enough. > > The mapping between devices and nodes isn't 1:1 but 1:0-n > > You need an agent run for every node and an agent for the device (to load > > the driver) > > I think I allowed for that already in that comment of mine you had > described as "theoretical"! (I was trying to describe the practice > of things in a general way ... surely that's one kind of theory. :-) > > By "node" presumably you mean "filesystem node"? Because I can't > see the sense of a device that doesn't show up in _any_ namespace > (filesystem, netdev, etc). No software could access it, right? Yes, I was refering to those things living in /dev ;-) A device invisible to user space isn't useless. A SCSI controller without devices attached is exactly that, yet it has its uses later. > > I am not sure. I think you need to call them independently. > > Have a look at how the USB hotplug agent works; they're called > independently, in that the per-device setup can get called even > if the driver hasn't been loaded. I may be dense today. All I can see is usb.c::usb_new_device() Regards Oliver _______________________________________________ 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