Gleb Natapov <g...@redhat.com> writes: > On Tue, Oct 26, 2010 at 11:57:53AM +0200, Markus Armbruster wrote: >> Gleb Natapov <g...@redhat.com> writes: >> >> > On Mon, Oct 25, 2010 at 07:53:41PM +0200, Markus Armbruster wrote: >> >> Gleb Natapov <g...@redhat.com> writes: >> >> >> >> > On Mon, Oct 25, 2010 at 05:10:15PM +0200, Markus Armbruster wrote: >> >> >> Gleb Natapov <g...@redhat.com> writes: >> >> >> >> >> >> > PCI bus already has one. For ISA bus this patch series uses device's >> >> >> > ioports to uniquely describe it. For isa-ide, for example, >> >> >> > get_dev_path >> >> >> > method returns: >> >> >> > 01f0-01f7,03f6 for first IDE controller >> >> >> > 0170-0177,0376 for second one >> >> >> >> >> >> Any I/O port used by the device identifies it. I'd say a common >> >> >> identifier is the "I/O base", the lowest I/O port used. >> >> > So use only first port from the string. More information is better then >> >> > less information. You can always drop information you do not need. >> >> >> >> I'd prefer canonical bus addresses to be terse. It's not the place to >> >> give additional information. >> > >> > I'd prefer them to give full info but not more. I don't see why you >> > point is more valid then mine. >> >> Full information about ISA resources is more than I/O ports, it also >> includes IRQs and DMA channels. > So you are arguing to add more info there? :) Theoretically there is > nothing that prevents ISA devices from sharing IRQ line (existing ISA > devices just not built to do that and nobody produces new once) and > DMA is separate device on ISA bus AFAIK. > >> >> An address is not the place to give full information. The purpose of an >> address is to name a thing, not to give full information about that >> thing. >> > Address should contain info that allows to find device easily. If > whoever looking for a device knows only one port device is using he > will not find the device if we'll use different port to name it. May be > not the problem in practice.
If he knows only one port, he can't form the address proposed by you. He needs to know *all* ports. So what he does is search all the devices for the one that uses the port in question. Same for the address I propose. The proposal differ for the case where the user remembers just the base address. I believe that's the common case. >> By the way, get_dev_path() really needs a written contract. Actually, >> all the qdev and qbus callbacks do. > What do you mean by that? It should be stable ABI, is this what you > mean? A contract between qdev core and the device models, so that device model authors know what exactly their callback functions are supposed to do. Stability is a separate matter. Since it's a purely internal interface, we don't want it.
