Messages in this thread | | | Date | Thu, 17 May 2001 00:11:55 +0200 | From | Ingo Oeser <> | Subject | Re: LANANA: To Pending Device Number Registrants |
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On Wed, May 16, 2001 at 02:36:44PM -0700, H. Peter Anvin wrote: > > But all devices which export a CD-ROM interface will do so. So the > > device node that is associated with the CD-ROM driver will export > > CD-ROM semantics, and the trailing name will be "/cd". > > > > Other interfaces a device exports, such as a CD-RW, appear as a > > different device node ("generic" for SCSI, because we have no CD-RW > > classification at this point). > > > > My scheme works already, and works reliably. Nothing had to be done to > > support the CD-ROM interface to CD-RW and DVD devices. > > > > It's still completely braindamaged: (a) these interfaces aren't > disjoint. They refer to the same device, and will interfere with each > other; (b) it is highly undesirable to tie the naming to the interfaces > in this way. It further restricts the namespaces you can export, for one > thing.
We do this already with ide-scsi. A device is visible as /dev/hda and /dev/sda at the same time. Or think IDE-CDRW: /dev/hda, /dev/sr0 and /dev/sg0.
All at the same time.
It is perfectly normal to export different interfaces for the same device. This is basically, what subfunctions on PCI do: Same device with different interfaces.
Just that we do it through a driver with ide and through the hardware with a multi function PCI card.
Applications don't care about devices. They care about entities that have capabilities and programming interfaces. What they _really_ are and if this is only emulated is not important.
Sorry, I don't see your point here :-(
Regards
Ingo Oeser -- 10.+11.03.2001 - 3. Chemnitzer LinuxTag <http://www.tu-chemnitz.de/linux/tag> <<<<<<<<<<<< been there and had much fun >>>>>>>>>>>> - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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